113 research outputs found
Colloidal topological insulators
Topological insulators insulate in the bulk but exhibit robust conducting
edge states protected by the topology of the bulk material. Here, we design a
colloidal topological insulator and demonstrate experimentally the occurrence
of edge states in a classical particle system. Magnetic colloidal particles
travel along the edge of two distinct magnetic lattices. We drive the colloids
with a uniform external magnetic field that performs a topologically
non-trivial modulation loop. The loop induces closed orbits in the bulk of the
magnetic lattices. At the edge, where both lattices merge, the colloids perform
skipping orbits trajectories and hence edge-transport. We also observe
paramagnetic and diamagnetic colloids moving in opposite directions along the
edge between two inverted patterns; the analogue of a quantum spin Hall effect
in topological insulators. We present a new, robust, and versatile way of
transporting colloidal particles, enabling new pathways towards lab on a chip
applications
Synthesis and Characterization of [Ir_2(TMB)_4H_2][B(C_6H_5)_4]_2·CH_3C_6H_5
The ^3(dσ *pσ) excited state of Ir_2(TMB)_4^(2+) (TMB = 2,5-diisocyano-2,5-dimethylhexane) reacts with hydrogen atom donors to give Ir_2(TMB)_4H_2^(2+) (Ir_2H_2). This d^7-d^7 dihydride has been isolated as a tetraphenylborate salt: v(Ir-H) 1940 cm^(-1), v(Ir-Ir) 136 cm^(-1). [Ir_2(TMB)_4H_2] [B(C_6H_5) _4]_2·CH_3C_6H_5, Ir_2C_(95)H_(114)N_8B_2, crystallizes in the monoclipic system, space group P2_1/c (No. 14), with a = 10.54 (2) Å, b = 31.02 (4) Å, and c = 27.05 (4) Å, β = 91.57 (3)°, V = 8841 (3) Å^3, and Z = 4. The Ir-Ir separation is 2.920 (2) Å, approximately 0.3 Å shorter than Ir-Ir in the d^8 dimer (lr_2) but ~0.1 Å longer than in the diiodide, Ir_2(TMB)_4I_2^(2+). The reaction of Ir_2H_2 with styrene gives Ir_2 and ethylbenzene
Synthesis and Characterization of [Ir_2(TMB)_4H_2][B(C_6H_5)_4]_2·CH_3C_6H_5
The ^3(dσ *pσ) excited state of Ir_2(TMB)_4^(2+) (TMB = 2,5-diisocyano-2,5-dimethylhexane) reacts with hydrogen atom donors to give Ir_2(TMB)_4H_2^(2+) (Ir_2H_2). This d^7-d^7 dihydride has been isolated as a tetraphenylborate salt: v(Ir-H) 1940 cm^(-1), v(Ir-Ir) 136 cm^(-1). [Ir_2(TMB)_4H_2] [B(C_6H_5) _4]_2·CH_3C_6H_5, Ir_2C_(95)H_(114)N_8B_2, crystallizes in the monoclipic system, space group P2_1/c (No. 14), with a = 10.54 (2) Å, b = 31.02 (4) Å, and c = 27.05 (4) Å, β = 91.57 (3)°, V = 8841 (3) Å^3, and Z = 4. The Ir-Ir separation is 2.920 (2) Å, approximately 0.3 Å shorter than Ir-Ir in the d^8 dimer (lr_2) but ~0.1 Å longer than in the diiodide, Ir_2(TMB)_4I_2^(2+). The reaction of Ir_2H_2 with styrene gives Ir_2 and ethylbenzene
Heart Failure with Preserved Ejection Fraction in African-Americans – The Atherosclerosis Risk in Communities (ARIC) Study
In an entirely African-American cohort, we compared clinical characteristics, cardiac structure and function, and all cause mortality in heart failure (HF) with preserved ejection fraction (HFpEF) in relation to HF with reduced ejection fraction (HFrEF) and those without HF
The QT interval and risk of incident atrial fibrillation
Abnormal atrial repolarization is important in the development of atrial fibrillation (AF), but no direct measurement is available in clinical medicine
Genome-wide association studies identify CHRNA5/3 and HTR4 in the development of airflow obstruction
RATIONALE: Genome-wide association studies (GWAS) have identified loci influencing lung function, but fewer genes influencing chronic obstructive pulmonary disease (COPD) are known.OBJECTIVES: Perform meta-analyses of GWAS for airflow obstruction, a key pathophysiologic characteristic of COPD assessed by spirometry, in population-based cohorts examining all participants, ever smokers, never smokers, asthma-free participants, and more severe cases.METHODS: Fifteen cohorts were studied for discovery (3,368 affected; 29,507 unaffected), and a population-based family study and a meta-analysis of case-control studies were used for replication and regional follow-up (3,837 cases; 4,479 control subjects). Airflow obstruction was defined as FEV(1) and its ratio to FVC (FEV(1)/FVC) both less than their respective lower limits of normal as determined by published reference equations.MEASUREMENTS AND MAIN RESULTS: The discovery meta-analyses identified one region on chromosome 15q25.1 meeting genome-wide significance in ever smokers that includes AGPHD1, IREB2, and CHRNA5/CHRNA3 genes. The region was also modestly associated among never smokers. Gene expression studies confirmed the presence of CHRNA5/3 in lung, airway smooth muscle, and bronchial epithelial cells. A single-nucleotide polymorphism in HTR4, a gene previously related to FEV(1)/FVC, achieved genome-wide statistical significance in combined meta-analysis. Top single-nucleotide polymorphisms in ADAM19, RARB, PPAP2B, and ADAMTS19 were nominally replicated in the COPD meta-analysis.CONCLUSIONS: These results suggest an important role for the CHRNA5/3 region as a genetic risk factor for airflow obstruction that may be independent of smoking and implicate the HTR4 gene in the etiology of airflow obstruction.</p
Genomic Variation Associated With Mortality Among Adults of European and African Ancestry With Heart Failure: The Cohorts for Heart and Aging Research in Genomic Epidemiology Consortium
Prognosis and survival are significant concerns for individuals with heart failure (HF). In order to better understand the pathophysiology of HF prognosis, the association between 2,366,858 single nucleotide polymorphisms (SNPs) and all-cause mortality was evaluated among individuals with incident HF from four community-based prospective cohorts: the Atherosclerosis Risk in Communities Study, the Cardiovascular Health Study, the Framingham Heart Study, and the Rotterdam Study
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