PAH/PAH(CF3)n Donor/Acceptor Charge-Transfer Complexes in Solution and in Solid-State Co-Crystals

A solution, solid-state, and computational study is reported of polycyclic aromatic hydrocarbon PAH/PAH(CF3)n donor/acceptor (D/A) charge-transfer complexes that involve six PAH(CF3)n acceptors with known gas-phase electron affinities that range from 2.11(2) to 2.805(15) eV and four PAH donors, including seven CT co-crystal X-ray structures that exhibit hexagonal arrays of mixed π-stacks with 1/1, 1/2, or 2/1 D/A stoichiometries (PAH=anthracene, azulene, coronene, perylene, pyrene, triphenylene; n=5, 6). These are the first D/A CT complexes with PAH(CF3)n acceptors to be studied in detail. The nine D/A combinations were chosen to allow several structural and electronic comparisons to be made, providing new insights about controlling D/A interactions and the structures of CT co-crystals. The comparisons include, among others, CT complexes of the same PAH(CF3)n acceptor with four PAH donors and CT complexes of the same donor with four PAH(CF3)n acceptors. All nine CT complexes exhibit charge-transfer bands in solution with λmax between 467 and 600 nm. A plot of E(λmax) versus [IE(donor)−EA(acceptor)] for the nine CT complexes studied is linear with a slope of 0.72±0.03 eV eV−1. This plot is the first of its kind for CT complexes with structurally related donors and acceptors for which precise experimental gas-phase IEs and EAs are known. It demonstrates that conclusions based on the common assumption that the slope of a CT E(λmax) versus [IE−EA] plot is unity may be incorrect in at least some cases and should be reconsidered. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinhei

An efficient method for measuring dissolved VOSCs in wastewater using GC-SCD with static headspace technique

Volatile organic sulfur compounds (VOSCs) are important sources of unpleasant odor in wastewater systems. However, the study of VOSCs is usually hindered by their complicated measurement method and highly reactive nature. In this work, a static headspace method utilising gas chromatography (GC) with a sulfur chemiluminescence detector (SCD) was developed to quantitatively analyze VOSCs in wastewater matrices. The method has low detection limits and requires no pre-concentration treatment. Three typical VOSCs, namely methanethiol (MT), dimethyl sulfide (DMS) and dimethyl disulfide (DMDS), were chosen as examples for this study. The calibration curves of all three compounds covering a wide range from 0.5 ppb to 500 ppb showed good linearity (R-2 > 0.999). The method detection limits (MDL) were 0.08, 0.12 and 0.21 ppb for MT, DMS and DMDS, respectively. The reproducibility (relative standard deviation) was approximately 2%. The recovery ratio of MT, DMS and DMDS in spiked wastewater samples were 83 +/- 4%, 103 +/- 4% and 102 +/- 3%, respectively. Sample preservation tests showed that VOSCs in wastewater samples could be preserved in vials without headspace under acidified conditions (pH similar to 1.1) for at least 24 h without significant changes

Dysregulation of heat shock protein 27 expression in oral tongue squamous cell carcinoma

<p>Abstract</p> <p>Background</p> <p>Recent proteomic studies identified Hsp27 as a highly over-expressed protein in oral squamous cell carcinoma (OSCC). Clinical studies that attempted to evaluate the prognostic values of Hsp27 yielded inconsistent results, which may be due to inclusion of OSCC cases from multiple anatomic sites. In this study, to determine the utility of Hsp27 for prognosis, we focused on oral tongue SCC (OTSCC), one of the most aggressive forms of OSCC.</p> <p>Methods</p> <p>Archival clinical samples of 15 normal oral tongue mucosa, 31 dysplastic lesions, 80 primary OTSCC, and 32 lymph node metastases were examined for Hsp27 expression by immunohistochemistry (IHC). Statistical analyses were carried out to assess the prognostic value of Hsp27 expression for patients with this disease.</p> <p>Results</p> <p>Dysregulation of Hsp27 expression was observed in dysplastic lesions, primary OTSCC, and lymph node metastases, and appears to be associated with disease progression. Statistical analysis revealed that the reduced Hsp27 expression in primary tumor tissue was associated with poor differentiation. Furthermore, the higher expression of Hsp27 was correlated with better overall survival.</p> <p>Conclusion</p> <p>Our study confirmed that the dysregulation of Hsp27 expression is a frequent event during the progression of OTSCC. The expression of Hsp27 appears to be an independent prognostic marker for patients with this disease.</p

Deregulation of manganese superoxide dismutase (SOD2) expression and lymph node metastasis in tongue squamous cell carcinoma

<p>Abstract</p> <p>Background</p> <p>Lymph node metastasis is a critical event in the progression of tongue squamous cell carcinoma (TSCC). The identification of biomarkers associated with the metastatic process would provide critical prognostic information to facilitate clinical decision making. Previous studies showed that deregulation of manganese superoxide dismutase (SOD2) expression is a frequent event in TSCC and may be associated with enhanced cell invasion. The purpose of this study is to further evaluate whether the expression level of SOD2 is correlated with the metastatic status in TSCC patients.</p> <p>Methods</p> <p>We first examined the SOD2 expression at mRNA level on 53 TSCC and 22 normal control samples based on pooled-analysis of existing microarray datasets. To confirm our observations, we examined the expression of SOD2 at protein level on an additional TSCC patient cohort (n = 100), as well as 31 premalignant dysplasias, 15 normal tongue mucosa, and 32 lymph node metastatic diseases by immunohistochemistry (IHC).</p> <p>Results</p> <p>The SOD2 mRNA level in primary TSCC tissue is reversely correlated with lymph node metastasis in the first TSCC patient cohort. The SOD2 protein level in primary TSCC tissue is also reversely correlated with lymph node metastasis in the second TSCC patient cohort. Deregulation of SOD2 expression is a common event in TSCC and appears to be associated with disease progression. Statistical analysis revealed that the reduced SOD2 expression in primary tumor tissue is associated with lymph node metastasis in both TSCC patient cohorts examined.</p> <p>Conclusions</p> <p>Our study suggested that the deregulation of SOD2 in TSCC has potential predictive values for lymph node metastasis, and may serve as a therapeutic target for patients at risk of metastasis.</p

Quick Assembly of 1-Alkylidenyl-tetrahydroisoquinolines via a Catellani Reaction/NBS-Mediated Cyclization Sequence and Synthetic Applications

We herein disclose a modular synthesis of 1-bromomethylene-THIQs involving a Catellani reaction of aryl iodides, aziridines, and terminal alkynes followed by an NBS-mediated cyclization. This approach features mild reaction conditions, wide substrate scope, good step-economy and good scalability. Based on this new method, we have accomplished the concise total synthesis of (±)-cularine, formal synthesis of 8-oxopseudopalmatine as well as the first total synthesis of dactyllactone A, demonstrating the wide synthetic potential of this method

Magnetostratigraphy of the Dali Basin in Yunnan and implications for late Neogene rotation of the southeast margin of the Tibetan Plateau

[1] The rotation pattern and fault activity in the southeast margin of the Tibetan Plateau (SEMTP) provide meaningful constraints on the geodynamic evolution of the plateau. However, the lack of Cenozoic paleomagnetic studies and accurate age constraints on Neogene sediments prevents a better understanding of the late Cenozoic tectonic activity in this area. To clarify the tectonic rotation pattern and deformation history of the SEMTP, we report new magnetostratigraphic data from a late Neogene sedimentary sequence in the Dali Basin, northwestern Yunnan Province, China. Rock magnetic analyses indicate that both magnetite and hematite are the main carriers of the characteristic remanent magnetizations (ChRMs). Magnetostratigraphic results show that the sedimentary profile spans from Chron C4n.1r to Chron C2n. The age of the sedimentary sequence in the Dali Basin can thus be paleomagnetically constrained to an interval from late Miocene to early Pleistocene. The basal age of the sediments is ~7.6 Ma, which indicates that the unroofing of Diancang Shan and activation of the Dali fault system were initiated at this time. The appearance of conglomerates and syntectonic sediments suggests the reactivation of the Dali fault system at ~2.5 Ma. Moreover, the overall mean ChRM direction suggests that the Dali Basin experienced significant (4.4 ± 2.5°), but minor post–late Miocene rotation. This indicates that most of the clockwise rotation demonstrated by previous paleomagnetic studies in the SEMTP occurred prior to late Miocene and may be concentrated between Eocene and Miocene, which is contemporaneous with the sinistral slip of the Ailao Shan-Red River fault

Tectonic and sedimentary evolution of the late Miocene-Pleistocene Dali Basin in the southeast margin of the Tibetan Plateau : Evidences from anisotropy of magnetic susceptibility and rock magnetic data

The Cenozoic Dali Basin, located at the northeast of Diancang Shan and south of the first bend of Yangtze River, is tectonically controlled by the Dali fault system in the southeast margin of the Tibetan Plateau. The basin is filled with late Miocene to Pleistocene fluviolacustrine sediments, which provide invaluable information about the tectonic deformation and drainage network reorganization in this area. In this study, we discuss the anisotropy of magnetic susceptibility (AMS) of the Dasongping section in the Dali Basin, which spans an interval from 7.6 to 1.8 Ma. Although rock magnetic experiments indicate that magnetite and hematite are the main remanence carriers, hysteresis loops, low values of bulk susceptibility and low temperature susceptibility suggest that paramagnetic minerals are major contributors to low-field AMS. The rock magnetic parameters indicate that the Dali Basin experienced four stages of infilling and the sediment sources may have changed at 4.2 Ma. The clustering of the minimum principle axes (Kmin) nearly perpendicular to the bedding plane and the pronounced N–S magnetic lineation parallel to the bedding plane indicate that the AMS of the Dali Basin is a superimposed fabric consisting of a sedimentary-compaction and a mild initial deformation overprint. The well-defined N–S magnetic lineation is likely due to the NNW and NNE oblique shear caused by the Heqing and Red River faults