Urinary 1-Hydroxypyrene Levels in Workers Exposed to Polycyclic Aromatic Hydrocarbon from Rubber Wood Burning

AbstractBackgroundUrinary 1-hydroxypyrene (1-OHP) was selected as a biomarker of polycyclic aromatic hydrocarbons (PAHs) to explore the accumulation level in the bodies of workers at rubber smoke sheet factories in southern Thailand.MethodsSpot urine samples were taken from four groups of workers from June 2006 to November 2007. The nonexposure or control groups included habitual cigarette smokers and nonsmokers. The other two groups were workers exposed to particle-bound PAHs from rubber wood smoke and they were nonsmokers. All spot urine samples were analyzed for 1-OHP and creatinine levels.ResultsThe mean ± standard deviation urinary 1-OHP in the control group of habitual smokers and the nonsmokers was 0.24 ± 0.16 μmol/mol creatinine and not-detected to 0.14 μmol/mol creatinine, respectively. In the workers, the 1-OHP levels on workdays had no significant difference from the 1-OHP levels on the days off. The yearly average 1-OHP level was 0.76 ± 0.41 μmol/mol creatinine whereas the average 1-OHP level during 10 consecutive workdays was 1.06 ± 0.29 μmol/mol creatinine (p > 0.05).ConclusionThe urinary 1-OHP levels of workers exposed to PAHs were high. The accumulation of 1-OHP in the body was not clear although the workers had long working hours with few days off during their working experience. Therefore, a regular day off schedule and rotation shift work during high productive RSS should be set for RSS workers

Homolytic C−H Bond Activation by Phosphine−Quinone-Based Radical Ion Pairs

Herein, we present the formation of transient radical ion pairs (RIPs) by single-electron transfer (SET) in phosphine−quinone systems and explore their potential for the activation of C−H bonds. PMes3 (Mes=2,4,6-Me3C6H2) reacts with DDQ (2,3-dichloro-5,6-dicyano-1,4-benzoquinone) with formation of the P−O bonded zwitterionic adduct Mes3P−DDQ (1), while the reaction with the sterically more crowded PTip3 (Tip=2,4,6-iPr3C6H2) afforded C−H bond activation product Tip2P(H)(2-[CMe2(DDQ)]-4,6-iPr2-C6H2) (2). UV/Vis and EPR spectroscopic studies showed that the latter reaction proceeds via initial SET, forming RIP [PTip3]⋅+[DDQ]⋅−, and subsequent homolytic C−H bond activation, which was supported by DFT calculations. The isolation of analogous products, Tip2P(H)(2-[CMe2{TCQ−B(C6F5)3}]-4,6-iPr2-C6H2) (4, TCQ=tetrachloro-1,4-benzoquinone) and Tip2P(H)(2-[CMe2{oQtBu−B(C6F5)3}]-4,6-iPr2-C6H2) (8, oQtBu=3,5-di-tert-butyl-1,2-benzoquinone), from reactions of PTip3 with Lewis-acid activated quinones, TCQ−B(C6F5)3 and oQtBu−B(C6F5)3, respectively, further supports the proposed radical mechanism. As such, this study presents key mechanistic insights into the homolytic C−H bond activation by the synergistic action of radical ion pairs.</p

Homolytic C−H Bond Activation by Phosphine−Quinone-Based Radical Ion Pairs

Herein, we present the formation of transient radical ion pairs (RIPs) by single-electron transfer (SET) in phosphine−quinone systems and explore their potential for the activation of C−H bonds. PMes3 (Mes=2,4,6-Me3C6H2) reacts with DDQ (2,3-dichloro-5,6-dicyano-1,4-benzoquinone) with formation of the P−O bonded zwitterionic adduct Mes3P−DDQ (1), while the reaction with the sterically more crowded PTip3 (Tip=2,4,6-iPr3C6H2) afforded C−H bond activation product Tip2P(H)(2-[CMe2(DDQ)]-4,6-iPr2-C6H2) (2). UV/Vis and EPR spectroscopic studies showed that the latter reaction proceeds via initial SET, forming RIP [PTip3]⋅+[DDQ]⋅−, and subsequent homolytic C−H bond activation, which was supported by DFT calculations. The isolation of analogous products, Tip2P(H)(2-[CMe2{TCQ−B(C6F5)3}]-4,6-iPr2-C6H2) (4, TCQ=tetrachloro-1,4-benzoquinone) and Tip2P(H)(2-[CMe2{oQtBu−B(C6F5)3}]-4,6-iPr2-C6H2) (8, oQtBu=3,5-di-tert-butyl-1,2-benzoquinone), from reactions of PTip3 with Lewis-acid activated quinones, TCQ−B(C6F5)3 and oQtBu−B(C6F5)3, respectively, further supports the proposed radical mechanism. As such, this study presents key mechanistic insights into the homolytic C−H bond activation by the synergistic action of radical ion pairs.</p

Offshore Wind Energy Conversion System Connected to the Electric Grid: Modeling and Simulation

This paper is on modeling and simulation for an offshore wind system equipped with a semi-submersible floating platform, a wind turbine, a permanent magnet synchronous generator, a multiple point clamped four level or five level full-power converter, a submarine cable and a second order filter. The drive train is modeled by three mass model considering the resistant stiffness torque, structure and tower in deep water due to the moving surface elevation. The system control uses PWM by space vector modulation associated with sliding mode and proportional integral controllers. The electric energy is injected into the electric grid either by an alternated current link or by a direct current link. The model is intend to be a useful tool for unveil the behavior and performance of the offshore wind system, especially for the multiple point clamped full-power converter, under normal operation or under malfunctions

Facile Synthesis of Tuneable Azophosphonium Salts

Azophosphonium salts have a facile synthesis and can be readily tuned at the para position of the aryl group and at the phosphorus position with the use of bulky phosphines, leading to a range of coloured compounds. A relation between the Hammett sigma(+)(para) constant and the colour and P-31 NMR chemical shift was explored. The compounds were characterised by NMR spectroscopy, UV/Vis spectroscopy and single-crystal X-ray structure crystallography.Peer reviewe

Insights into single-electron-transfer processes in frustrated lewis pair chemistry and related donor-acceptor systems in main group chemistry

The activation and utilization of substrates mediated by Frustrated Lewis Pairs (FLPs) was initially believed to occur solely via a two-electron, cooperative mechanism. More recently, the occurrence of a single-electron transfer (SET) from the Lewis base to the Lewis acid was observed, indicating that mechanisms that proceed via one-electron-transfer processes are also feasible. As such, SET in FLP systems leads to the formation of radical ion pairs, which have recently been more frequently observed. In this review, we aim to discuss the seminal findings regarding the recently established insights into the SET processes in FLP chemistry as well as highlight examples of this radical formation process. In addition, applications of reported main group radicals will also be reviewed and discussed in the context of the understanding of SET processes in FLP systems

Developing Classifications of Laryngeal Dysplasia: The Historical Basis

During the last 60 years numerous significant attempts have been made to achieve a widely acceptable terminology and histological grading for laryngeal squamous intraepithelial lesions. While dysplasia was included in the pathology of the uterine cervix already in 1953, the term dysplasia was accepted in laryngeal pathology first after the Toronto Centennial Conference on Laryngeal Cancer in 1974. In 1963 Kleinsasser proposed a three-tier classification, and in 1971 Kambic and Lenart proposed a four-tier classification. Since then, four editions of the World Health Organisation (WHO) classification have been proposed (1978, 1991, 2005 and 2017). Several terms such as squamous intraepithelial neoplasia (SIN) and laryngeal intraepithelial neoplasia (LIN) are now being abandoned and replaced by squamous intraepithelial lesions (SIL). The essential change between the 2005 and 2017 WHO classifications is the attempt to induce a simplification from a four- to a two-tier system. The current WHO classification (2017) thus recommends the use of a two-tier system with reasonably clear histopathological criteria for the two groups: low-grade and high-grade dysplasia. Problems with interobserver variability apart, subjectivities and uncertainties remain, but to a lesser degree. Ongoing and additional molecular studies may help to clarify underlying events that will increase our understanding and possibly can facilitate our attempts to obtain an even better classification. The classification needs to be easier for the general pathologist to perform and easier for the clinician to interpret. These two objectives are equally important to provide each patient the best personalised treatment available for squamous intraepithelial lesions.Peer reviewe

Формування органів управління кінематографа в Україні (1919)

У статті розглядається процес створення та діяльність органів управління кінематографа в перші роки функціонування радянської влади в Україні.В статье рассматривается процесс создания и деятельность органов управления кинематографа в первые годы функционирования советской власти в Украине.The process of creating and functioning of the cinematography authorities in the early years of the Soviet Union in Ukraine is examined in the article

Clear cell chondrosarcoma of the head and neck

Clear cell chondrosarcoma is a rare variant of chondrosarcoma that mostly involves the end of long bones. However, nine cases have been reported in the head and neck: four in larynx, two in nasal septum, two in maxilla and one in the skull. These cases form the basis of this review. Head and neck cases accounts for less than 5% of Clear cell chondrosarcomas in the whole body and the larynx is the most common place. The histological findings of head and neck cases are consistent with general features of this entity in the whole body and nearly all tumors in this case series had a component of conventional chondrosarcoma. Clear cell chondrosarcoma is an intracompartmental tumor and retains "Grenz zone" just beneath the epithelium. Therefore, the overlying mucosa remained intact in all laryngeal cases. Nasal tumor caused ballooning of the septum and the maxillary lesion did not involve the oral mucosa. This tumor presents various radiographic features in the head and neck area. Chondroblastoma, chondroma, osteoblastoma, osteosarcoma and metastatic renal cell carcinoma are included in the histologic differential diagnoses. Differentiation from chondroblastic osteosarcoma is important in the maxilla. A wide resection is adequate in most cases. However, some laryngeal cases show tendency to recur. Clear cell chondrosarcoma is a slow growing tumor and this necessitates a long time follow-up of patients. Due to the extreme rarity in the head and neck, diagnosis of Clear cell chondrosarcoma in this area, must be confirmed by histochemical and immunohistochemical studies

Piezoelectric-assisted removal of a benign fibrous histiocytoma of the mandible: An innovative technique for prevention of dentoalveolar nerve injury

In this article, we present our experience with a piezoelectric-assisted surgical device by resection of a benign fibrous histiocytoma of the mandible