Increasing Chemical Diversity of B2 N2 Anthracene Derivatives by Introducing Continuous Multiple Boron-Nitrogen Units.

Increasing the chemical diversity of organic semiconductors is essential to develop efficient electronic devices. In particular, the replacement of carbon-carbon (C-C) bonds with isoelectronic boron-nitrogen (B-N) bonds allows precise modulation of the electronic properties of semiconductors without significant structural changes. Although some researchers have reported the preparation of B2 N2 anthracene derivatives with two B-N bonds, no compounds with continuous multiple BN units have been prepared yet. Herein, we report the synthesis and characterization of a B2 N2 anthracene derivative with a BNBN unit formed by converting the BOBN unit at the zigzag edge. Compared to the all-carbon analogue 2-phenylanthracene, BNBN anthracene exhibits significant variations in the C-C bond length and a larger highest occupied molecular orbital-lowest unoccupied molecular orbital energy gap. The experimentally determined bond lengths and electronic properties of BNBN anthracene are confirmed through theoretical calculations. The BOBN anthracene organic light-emitting diode, used as a blue host, exhibits a low driving voltage. The findings of this study may facilitate the development of larger acenes with multiple BN units and potential applications in organic electronics.

Unveiling 79-Year-Old Ixene and Its BN-Doped Derivative.

Polycyclic aromatic hydrocarbons (PAHs) are key components of organic electronics. The electronic properties of these carbon-rich materials can be controlled through doping with heteroatoms such as B and N, however, few convenient syntheses of BN-doped PAHs have been reported. Described herein is the rationally designed, two-step syntheses of previously unknown ixene and BN-doped ixene (B2 N2 -ixene), and their characterizations. Compared to ixene, B2 N2 -ixene absorbs longer-wavelength light and has a smaller electrochemical energy gap. In addition to its single-crystal structure, scanning tunneling microscopy revealed that B2 N2 -ixene adopts a nonplanar geometry on a Au(111) surface. The experimentally obtained electronic structure of B2 N2 -ixene and the effect of BN-doping were confirmed by DFT calculations. This synthesis enables the efficient and convenient construction of BN-doped systems with extended π-conjugation that can be used in versatile organic electronics applications.

Dalotuzumab in chemorefractory KRAS exon 2 mutant colorectal cancer: Results from a randomised phase II/III trial.

Limited data are available on the efficacy of anti-IGF-1R agents in KRAS mutant colorectal cancer (CRC). We analysed the outcome of 69 chemorefractory, KRAS exon 2 mutant CRC patients who were enrolled in a double-blind, randomised, phase II/III study of irinotecan and cetuximab plus dalotuzumab 10 mg/kg once weekly (arm A), dalotuzumab 7.5 mg/kg every second week (arm B) or placebo (arm C). Objective response rate (5.6% vs. 3.1% vs. 4.8%), median progression-free survival (2.7 vs. 2.6 vs. 1.4 months) and overall survival (7.8 vs. 10.3 vs. 7.8 months) were not statistically significantly different between treatment groups. Most common grade ≥3 treatment-related toxicities included neutropenia, diarrhoea, hyperglycaemia, fatigue and dermatitis acneiform. Expression of IGF-1R, IGF-1, IGF-2 and EREG by quantitative real-time polymerase chain reaction was assessed in 351 patients from the same study with available data on KRAS exon 2 mutational status. Median cycle threshold values for all biomarkers were significantly lower (i.e., higher expression, p < 0.05) among patients with KRAS wild-type compared to those with KRAS exon 2 mutant tumours. No significant changes were found according to location of the primary tumour with only a trend towards lower expression of IGF-1 in colon compared to rectal cancers (p = 0.06). Albeit limited by the small sample size, this study does not appear to support a potential role for anti-IGF-1R agents in KRAS exon 2 mutant CRC. Data on IGF-1R, IGF-1 and IGF-2 expression here reported may be useful for patient stratification in future trials with inhibitors of the IGF pathway.

Surface-Effect-Induced Optical Bandgap Shrinkage in GaN Nanotubes.

We investigate nontrivial surface effects on the optical properties of self-assembled crystalline GaN nanotubes grown on Si substrates. The excitonic emission is observed to redshift by ∼100 meV with respect to that of bulk GaN. We find that the conduction band edge is mainly dominated by surface atoms, and that a larger number of surface atoms for the tube is likely to increase the bandwidth, thus reducing the optical bandgap. The experimental findings can have important impacts in the understanding of the role of surfaces in nanostructured semiconductors with an enhanced surface/volume ratio.

Synthesis of Nitrogen-Containing Rubicene and Tetrabenzopentacene Derivatives.

Carbon-based materials, such as acenes, fullerenes, and graphene nanoribbons, are viewed as the potential successors to silicon in the next generation of electronics. Although a number of methodologies provide access to these materials' all-carbon variants, relatively fewer strategies readily furnish their nitrogen-doped analogues. Herein, we report the rational design, preparation, and characterization of nitrogen-containing rubicenes and tetrabenzopentacenes, which can be viewed either as acene derivatives or as molecular fragments of fullerenes and graphene nanoribbons. The reported findings may prove valuable for the development of electron transporting organic semiconductors and for the eventual construction of larger carbonaceous systems.

Ultimate eradication rate of Helicobacter pylori after first, second, or third-line therapy in Korea.

BACKGROUND AND AIMS: Resistance rates of Helicobacter pylori to clarithromycin, metronidazole, and quinolone are over 30% in South Korea. The aim of this prospective study was to evaluate the ultimate eradication rate of H. pylori after first, second, or third-line therapy in Korea. METHODS: A cohort of 2202 patients with H. pylori was treated with proton pump inhibitor (PPI)-based triple therapy for seven days. In case of treatment failure or recurrence, moxifloxacin-based triple therapy (MA) or bismuth-based quadruple therapy (QUAD) was randomly given. When the second-line treatment failed or H. pylori recurred, the unused MA or QUAD was used as a third-line treatment. RESULTS: Eighty-six patients had recurrence at least once during consecutive lines of treatments. Among 2116 patients (intention-to-treat [ITT]) without recurrence, 1644 (77.7%, per-protocol [PP]) completely followed our treatment flow. The ITT and PP rates of first-line treatment were 69.8% and 89.3%. After second line, they reached 78.4% (ITT) and 98.4% (PP). The "final" eradication rate up to third line treatment were 80.0% (1692/2116) and 99.8% (1641/1644), respectively. Resistance to clarithromycin showed significantly lower eradication rate (OR 0.358, P < 0.001) than those with susceptible strains in multivariate analysis. However in PP analysis, there was no significant difference in ultimate success rate regarding resistance pattern. CONCLUSION: Final success rate of PP was high, 99.8% in Korea in spite of high antibiotic resistance rates. However, high rate of refusal of further treatment and follow-up loss made ITT eradication rate low. Proper strategy to improve the treatment adherence is needed.

Synthesis of polybenzoquinolines as precursors for nitrogen-doped graphene nanoribbons.

Graphene nanoribbons (GNRs) represent promising materials for the next generation of nanoscale electronics. However, despite substantial progress towards the bottom-up synthesis of chemically and structurally well-defined all-carbon GNRs, strategies for the preparation of their nitrogen-doped analogs remain at a nascent stage. This scarce literature precedent is surprising given the established use of substitutional doping for tuning the properties of electronic materials. Herein, we report the synthesis of a previously unknown class of polybenzoquinoline-based materials, which have potential as GNR precursors. Our scalable and facile approach employs few synthetic steps, inexpensive commercial starting materials, and straightforward reaction conditions. Moreover, due to the importance of quinoline derivatives for a variety of applications, the reported findings may hold implications across a diverse range of chemical and physical disciplines.

Polymerization of tellurophene derivatives by microwave-assisted palladium-catalyzed ipso-arylative polymerization.

We report the synthesis of a tellurophene-containing low-bandgap polymer, PDPPTe2T, by microwave-assisted palladium-catalyzed ipso-arylative polymerization of 2,5-bis[(α-hydroxy-α,α-diphenyl)methyl]tellurophene with a diketopyrrolopyrrole (DPP) monomer. Compared with the corresponding thiophene analog, PDPPTe2T absorbs light of longer wavelengths and has a smaller bandgap. Bulk heterojunction solar cells prepared from PDPPTe2T and PC71 BM show PCE values of up to 4.4%. External quantum efficiency measurements show that PDPPTe2T produces photocurrent at wavelengths up to 1 µm. DFT calculations suggest that the atomic substitution from sulfur to tellurium increases electronic coupling to decrease the length of the carbon-carbon bonds between the tellurophene and thiophene rings, which results in the red-shift in absorption upon substitution of tellurium for sulfur.

Controlling ferromagnetic easy axis in a layered MoS2 single crystal.

We report the effective methods to induce weak ferromagnetism in pristine MoS2 persisting up to room temperature with the improved transport property, which would lead to new spintronics devices. The hydrogenation of MoS2 by heating at 300 °C for 1 h leads to the easy axis out of plane, while the irradiation of proton with a dose of 1 × 10(13) P/cm(2) leads to the easy axis in plane. The theoretical modeling supports such magnetic easy axes.

Accuracy of diagnostic tests for Helicobacter pylori in patients with peptic ulcer bleeding.

BACKGROUND AND AIMS: To assess the validity of biopsy-based tests (histology, culture, and urease test) and serology in detecting current H. pylori infection for the peptic ulcer patients who had gastric bleeding. METHODS: A total of 398 peptic ulcer patients were enrolled and divided into two groups, according to the presence or absence of bleeding. The diagnosis for current H. pylori infection was verified using the gold standard combining individual H. pylori tests. Sensitivity, specificity, and positive and negative predictive values of the culture, Campylobacter-like organism (CLO) test (urease test), histology, and serology were compared. RESULTS: Of the total study population (N = 398), 157 (39.4%) patients were categorized into the bleeding group. The sensitivities of the culture (40.0%) and CLO (85.0%) in the bleeding group were significantly lower than culture (58.1%) and CLO (96.4%) in the nonbleeding group (p = .012 and p < .001, respectively). In the bleeding group, the sensitivity of CLO (85.0%) was significantly lower than histology (92.5%) and serology (97.4%) (p = .013 and p = .002, respectively), which was not found in the nonbleeding group. The specificity of serology in the bleeding group (56.3%) was significantly lower than that of nonbleeding group (74.2%) (p = .038). Similarly, the specificity of serology was significantly lower than the other H. pylori tests in the bleeders. CONCLUSIONS: Bleeding decreased the sensitivity of H. pylori tests in patients with peptic ulcer, especially in urease test or culture. In contrast, histology was found to be a quite reliable test, regardless of the presence of bleeding.

Conductance of single cobalt chalcogenide cluster junctions.

Understanding the electrical properties of semiconducting quantum dot devices have been limited due to the variability of their size/composition and the chemistry of ligand/electrode binding. Furthermore, to probe their electrical conduction properties and its dependence on ligand/electrode binding, measurements must be carried out at the single dot/cluster level. Herein we report scanning tunneling microscope based break junction measurements of cobalt chalcogenide clusters with Te, Se and S to probe the conductance properties. Our measured conductance trends show that the Co-Te based clusters have the highest conductance while the Co-S clusters the lowest. These trends are in very good agreement with cyclic voltammetry measurements of the first oxidation potentials and with density functional theory calculations of their HOMO-LUMO gaps.

Persistent status of metabolic syndrome and risk of cholangiocarcinoma: A Korean nationwide population-based cohort study.

OBJECTIVE: It is unknown whether persistent metabolic syndrome (MetS) is associated with an increased risk of cholangiocarcinoma (CCA). Therefore, we investigated the risk of CCA according to changes in MetS status. RESEARCH DESIGN AND METHODS: This nationwide cohort study included 8,581,407 adults who underwent anthropometric measurements and laboratory tests in two consecutive national health screenings during 2009-2012 and observed the subjects until 2017. Individuals with cancer, or follow-up duration <1 year were excluded (n = 377,915). Subjects were classified into the MetS-free, MetS-developed, MetS-improved, and MetS-persistent groups. The outcome was the incidence of CCA, identified using the claims database. Multivariable Cox proportional hazards regression models were used. RESULTS: Among the 8,203,492 subjects (mean age 48.9 ± 12.8 years; 56.7% male), 7506 CCA patients were newly identified during a median follow-up of 5.1 years. The probability of CCA was consistently higher in the MetS-persistent group than in the MetS-free group (P < 0.001). MetS-persistent status was significantly associated with an increased risk of CCA compared with the MetS-free status (unadjusted hazard ratio [HR] 2.8, 95% confidence interval [CI] 2.66-2.95), even after adjusting for multiple covariates (adjusted HR 1.07, 95% CI 1.01-1.13). Improved or newly developed MetS was not associated with CCA risk in the fully adjusted model (aHR 1.02, 95% CI 0.94-1.10 and aHR 0.99, 95% CI 0.92-1.06, respectively). CONCLUSIONS: MetS was associated with an increased risk of CCA if it persisted for ≥2 years. Our finding suggests that MetS may be a potentially modifiable risk factor for CCA.

PN-Doped tetraphenylnaphthalene: a straightforward synthetic strategy analogous to BN-annulation.

Compared to BN heterocycles, few studies on PN heterocycles have been reported to date. Herein, we developed an efficient synthetic strategy analogous to BN-annulation to simultaneously incorporate a PN bond and a halogen group into the naphthalene core. Subsequently, we prepared PN-containing tetraphenylnaphthalene using this method, followed by palladium-catalyzed cross-coupling and reduction reactions. The prepared molecule was characterized via X-ray crystallography, NMR spectroscopy, UV-vis spectroscopy, and cyclic voltammetry.

An aza-Diels-Alder approach to chlorinated quinolines, benzoquinolines, and polybenzoquinolines.

Quinolines and quinoline-containing macromolecules are renowned for their valuable biological activities and excellent materials properties. Herein, we validate a general strategy for the synthesis of chloro-containing quinoline, benzoquinoline and polybenzoquinoline variants via the aza-Diels-Alder reaction. The described findings could be ultimately implemented in other synthetic pathways and may open new opportunities for analogous quinoline-derived materials.

Ten-day sequential therapy as first-line treatment for Helicobacter pylori infection in Korea: a retrospective study.

BACKGROUND AND AIMS: The eradication rate of proton-pump inhibitor-based triple therapy for Helicobacter pylori infection is low due to increasing antibiotics resistance, especially clarithromycin. Recently, it was reported in Europe that a 10-day sequential strategy produced good outcomes. The aim of this study was to assess the efficacy of sequential therapy as first-line treatment for eradication of H. pylori in clinical practice in Korea. MATERIALS AND METHODS: A total of 98 patients (mean age 55.2 years and male 47, female 51) with proven H. pylori infection received 10-day sequential therapy (20 mg of rabeprazole, and 1 g of amoxicillin, twice daily for the first 5 days, followed by 20 mg of rabeprazole, 500 mg of clarithromycin, and 500 mg of metronidazole, twice daily for the remaining 5 days). Eradication was evaluated 4 weeks later, after completion of treatment by 13(C)-urea breath testing. Eradication rates were calculated by intention-to-treat (ITT) and by per protocol (PP). Compliance and adverse events were also assessed in study group. RESULTS: The eradication rate of sequential therapy was 91.8% (90/98) by ITT and same result was reported by PP analysis (89/97). The study group consisted of 66 H. pylori associated gastritis, 7 gastric ulcer, and 25 duodenal ulcer patients (67.3%, 7.1%, 25.5%, respectively). Mild adverse events happened frequently (21.4%) but the treatment was well tolerable. The most common adverse event was a bitter taste (9.2%) followed by nausea and diarrhea (4.1%). CONCLUSIONS: Ten-day sequential therapy is found to effectively eradicate H. pylori infection as first-line treatment in Korea.

Quantum confined Stark effect of InGaN/GaN multi-quantum disks grown on top of GaN nanorods.

We have investigated, using micro-photoluminescence, the quantum confined Stark effect in an In(x)Ga(1-x)N/GaN multi-quantum disk structure at the tip of a single GaN nanorod. A strong and sharp emission line from the In(x)Ga(1-x)N/GaN quantum disks near 3.26 eV was observed. The peak energy of the emission line was observed to blue-shift with increasing excitation power, indicating a quantum confined Stark effect. Furthermore, both the blue-shift and the intensity of the emission saturate with increasing excitation power. The temperature-dependence of the 3.26 eV emission line has also been investigated.

Anisotropic shape evolution of large-size Cu nanocrystals prepared in nonionic microemulsion media.

We report the anisotropic shape evolution of colloidal copper nanocrystals (Cu NCs) in nonionic microemulsion media by adopting tetraethylammonium hydroxide as a reactant and capping agent in water phase. Relatively large-size Cu NCs were synthesized to confine the growth of Cu NCs below 100 nm. TEM images showed the triangular and hexagonal morphologies of Cu NCs ranging over 55-70 nm after 28 h, while they showed the spherical NCs dominantly under higher concentration of a reducing agent. The surface plasmon resonance (SPR) absorption band of anisotropic Cu NCs was centered at 571 nm with signal enhancement over time. The formation kinetics revealed that the gradual conversion of the Cu seeds into larger NCs during 28 h at room temperature. The NCs were characterized to be Cu rather than CuO or Cu2O by electron diffraction patterns, exhibiting relevant d-spacing figures consistent with the bulk Cu crystal.

Toll-like receptor distribution in colonic epithelium and lamina propria is disrupted in HIV viremic, immune success, and failure.

DESIGN: Since intestinal immunity and the microbiome are disrupted in HIV disease, we studied the abundance of innate immune sensors, Toll-like receptors (TLRs), in the mucosa of participants with viremia, prior to antiretroviral therapy (ART), immune success (>500 CD4 T cells/µl after 2 years of ART; suppressed viremia), and immune failure (<350 CD4 T cells/µl after 2 years of ART; suppressed viremia). We hypothesized that disruption of intestinal TLR abundance and location provides a mechanism behind persistent inflammation. METHODS: Immunofluorescence for TLR3, TLR4, and TLR9 on paraffin embedded biopsies from uninfected, viremic, immune success, and immune failure colons was imaged by deconvolution microscopy and quantified with MetaMorph software. Plasma levels of C-reactive protein, IL-6, and intestinal fatty-acid binding protein (I-FABP) were correlated with TLR expression. RESULTS: Viremic participants have significantly higher levels of TLR3 and TLR9 on surface epithelium and in crypts when compared with uninfected controls. TLR3 is further elevated in immune failure and immune success. TLR9 abundance remains elevated in immune failure and is normalized in immune success. TLR9 expression in the crypt and lamina propria positively associates with C-reactive protein and IL-6 and negatively with I-FABP. TLR4 is significantly lower on surface epithelium and higher in crypts in viremic. Its expression in the lamina propria positively correlates with IL-6 and negatively correlates with I-FABP. CONCLUSION: Mucosal TLR imbalance and deregulation, and the resulting mucosal TLR desensitization and hypervigilance, remain after suppressive ART, in the presence or absence of T-cell recovery, likely contributing to chronic systemic inflammation.

Impact of sphingosine and acetylsphingosines on the aggregation and toxicity of metal-free and metal-treated amyloid-ß.

Pathophysiological shifts in the cerebral levels of sphingolipids in Alzheimer's disease (AD) patients suggest a link between sphingolipid metabolism and the disease pathology. Sphingosine (SP), a structural backbone of sphingolipids, is an amphiphilic molecule that is able to undergo aggregation into micelles and micellar aggregates. Considering its structural properties and cellular localization, we hypothesized that SP potentially interacts with amyloid-ß (Aß) and metal ions that are found as pathological components in AD-affected brains, with manifesting its reactivity towards metal-free Aß and metal-bound Aß (metal-Aß). Herein, we report, for the first time, that SP is capable of interacting with both Aß and metal ions and consequently affects the aggregation of metal-free Aß and metal-Aß. Moreover, incubation of SP with Aß in the absence and presence of metal ions results in the aggravation of toxicity induced by metal-free Aß and metal-Aß in living cells. As the simplest acyl derivatives of SP, N-acetylsphingosine and 3-O-acetylsphingosine also influence metal-free Aß and metal-Aß aggregation to different degrees, compared to SP. Such slight structural modifications of SP neutralize its ability to exacerbate the cytotoxicity triggered by metal-free Aß and metal-Aß. Notably, the reactivity of SP and the acetylsphingosines towards metal-free Aß and metal-Aß is determined to be dependent on their formation of micelles and micellar aggregates. Our overall studies demonstrate that SP and its derivatives could directly interact with pathological factors in AD and modify their pathogenic properties at concentrations below and above critical aggregation concentrations.

Frustrated rotations in single-molecule junctions.

We compare the conductance of 1,4-bis(methylthio)benzene with that of 2,3,6,7-tetrahydrobenzo[1,2-b:4,5-b']dithiophene and the conductance of 1,4-bis(methylseleno)benzene with that of 2,3,6,7-tetrahydrobenzo[1,2-b:4,5-b']diselenophene and show explicitly that the orientation of an Au-S or Au-Se bond relative to the aromatic pi system controls electron transport through conjugated molecules. Specifically, we have found that the conduction pathway connects the Au electrodes to the aromatic pi-system via the chalcogen p lone pairs, and greater overlaps among these components lead to higher conductivity through the molecular junction.