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Behzad Heibati, Krystal J Godri Pollitt, Jamshid Yazdani Charati, Alan Ducatman, Mohammad Shokrzadeh, Ali Karimi, Mahmoud Mohammadyan
Elevated emissions of volatile organic compounds, including benzene, toluene, ethylbenzene, and o, p, and m-xylenes (BTEX), are an occupational health concern at oil transfer stations. This exploratory study investigated personal exposure to BTEX through environmental air and urine samples collected from 50 male workers at a major oil distribution company in Iran. Airborne BTEX exposures were evaluated over 8h periods during work-shift by using personal passive samplers. Urinary BTEX levels were determined using solid-phase microextraction with gas chromatography mass spectrometry for separation and detection...
November 13, 2017: Ecotoxicology and Environmental Safety
Hanns Moshammer, Michael Poteser
Benzene is an established carcinogenic substance [1,2].[...].
November 16, 2017: International Journal of Environmental Research and Public Health
Somnath Das, Palani Natarajan, Burkhard König
The C-H amination of benzene derivatives was achieved using DDQ as photocatalyst and BocNH₂ as the amine source under aerobic conditions and visible light irradiation. Electron-deficient and electron-rich benzenes react as substrates with moderate to good product yields. The amine scope of the reaction comprises Boc-amine, carbamates, pyrazoles, sulfonimide and urea. Preliminary mechanistic investigations indicate a charge transfer complex between the amine and DDQ as essential intermediate of the reaction...
November 16, 2017: Chemistry: a European Journal
K Uematsu, K Noguchi, K Nakano
A series of [7]helicene and [7]helicene-like compounds composed of a cyclopenta[1,2-b:4,3-b']dithiophene or dithieno[2,3-b:3',2'-d]heterole moiety and two naphthalene moieties were successfully synthesized from a common synthetic intermediate, 1,1'-binaphtho[2,1-b]thiophene. Their helical structures were confirmed by X-ray crystallographic analysis. The photophysical properties of them and their benzene analogues were investigated via absorption and fluorescence spectroscopy and theoretical calculations to correlate the effect of the five-membered rings in their π-conjugated skeleton...
November 16, 2017: Physical Chemistry Chemical Physics: PCCP
Erik P Hoy, David A Mazziotti, Tamar Seideman
Can an electronic device be constructed using only a single molecule? Since this question was first asked by Aviram and Ratner in the 1970s [Chem. Phys. Lett. 29, 277 (1974)], the field of molecular electronics has exploded with significant experimental advancements in the understanding of the charge transport properties of single molecule devices. Efforts to explain the results of these experiments and identify promising new candidate molecules for molecular devices have led to the development of numerous new theoretical methods including the current standard theoretical approach for studying single molecule charge transport, i...
November 14, 2017: Journal of Chemical Physics
Gaoyang Deng, Zhonggang Wang
Triptycene-based cyanate monomers 2,6,14-tricyanatotriptycene (TPC) and 2,6,14-tris(4-cyanatophenyl)triptycene (TPPC) that contain different numbers of benzene rings per molecule were synthesized, from which two microporous cyanate resins PCN-TPC and PCN-TPPC were prepared. Of interest is the observation that the two polymers have very similar porosity parameters, but PCN-TPPC uptakes considerably higher benzene (77.8 wt %) than PCN-TPC (17.6 wt %) at room temperature since the higher concentration of phenyl groups in PCN-TPPC enhances the π-π interaction with benzene molecules...
November 15, 2017: ACS Applied Materials & Interfaces
Hai Ning Chang, Suo Xia Hou, Zeng Chuan Hao, Guang Hua Cui
Nano-structures of [Zn(L)(atpt)]n (1) (L=1,2-bis(2-methylbenzimidazol-1-ylmethyl)benzene and H2atpt=2-aminoterephthalic acid) were obtained by hydrothermal and sonochemical approaches, characterized by scanning electron microscopy (SEM), IR, powder X-ray diffraction (PXRD), and elemental analysis. CP 1 features a 2D (4,4) network with the point symbol {4(4).6(2)}, the 3D supramolecular architecture in CP 1 is controlled through π⋯π stacking interactions. The influence of various concentrations of initial reagents, power of ultrasound irradiation, and ultrasound time on the morphology and size of nano-structured CP 1 were studied in detail...
March 2018: Ultrasonics Sonochemistry
Mohammad Dinari, Elahe Salehi, Amir Abdolmaleki
A new poly(benzimidazole-amide) (PBIA) was fabricated by polycondensation of 1,3-bis(5-amino-1H-benzimidazole-2-yl)benzene with chiral diacid under green media by using tetra-n-butylammonium bromide as a cheap commercially available molten ionic salt at 120°C. The affection of reaction time on the polymer yield and viscosity was tested and optimized for PBIA. Inherent viscosity value of the prepared PBIA under optimized conditions is 0.31dL/g. Then to acquire a uniformly dispersion of graphene oxide (GO) in the PBIA matrix, GO was prepared through strong oxidation procedure...
March 2018: Ultrasonics Sonochemistry
Haixu Zhang, Jinian Shu, Bo Yang, Peng Zhang, Pengkun Ma
Many organic amines that comprise a benzene ring are policy-sensitive because of their toxicity and links to social harm. However, to date, detection of such compounds mainly relies on offline methods. This study proposes an online pptv (parts per trillion by volume) level of detection method for amines, using the recently-built vacuum ultraviolet photoionization mass spectrometer (VUV-PIMS) combined with a new doping technique. Thus, the dichloromethane doping-assisted photoionization mass spectra of aniline, benzylamine, phenethylamine, amphetamine, and their structural isomers were recorded...
February 1, 2018: Talanta
Yanzhe Li, Zhe Sheng, Chuanlei Zhu, Wei Yin, Changhu Chu
Crown ether is a type of typical macrocyclic polyether compounds, which can produce strong interactions with cationic species, such as metal ions and protonated amines due to its cavity structure and the strong electronegative effect of heteroatoms on the crown ether ring. In this paper, a type of silica based crown ether stationary phase was prepared by covalently bonding dibenzo-18-crown 6-ether (DBCE) on silica gel via copper (I) catalyzed azide-alkyne 1,3-dipolar cycloaddition (CuAAC). The tetraazido DBCE was rapidly prepared by bromomethylation and subsequent azido substitution of DBCE...
February 1, 2018: Talanta
Fangling Wu, Chongsheng Xu, Nan Jiang, Jiabin Wang, Chuan-Fan Ding
A poly (methacrylic acid-co-divinyl-benzene) [poly (MAA-co-DVB)] monolithic column was specially prepared according to the chemical structures of the three mycotoxins of aflatoxin B1, zearalenone and sterigmatocystin, and used for in-tube solid-phase microextraction (in-tube SPME) of the selected mycotoxins. The poly (MAA-co-DVB) monolithic column was characterized in detail, and exhibited effective hydrophobic, π-π, and hydrogen bonding interactions towards the target analytes. By coupling the poly (MAA-co-DVB) monolithic column-based in-tube SPME with high-performance liquid chromatography, a simple, sensitive and matrix effect-free method for determination of mycotoxins was developed...
February 1, 2018: Talanta
Frank Eisenhut, Thomas Lehmann, Andreas Viertel, Dmitry Skidin, Justus Krüger, Seddigheh Nikipar, Dmitry A Ryndyk, Christian Joachim, Stefan Hecht, Francesca Moresco, Gianaurelio Cuniberti
We investigated the thermally induced on-surface cyclization of 4,10-bis(2'-bromo-4'-methylphenyl)-1,3-dimethylpyrene to form the previously unknown, non-alternant polyaromatic hydrocarbon diindeno[1,2,3-cd:1´,2´,3´-mn]pyrene on Au(111) using scanning tunneling microscopy and spectroscopy. The observed unimolecular reaction involves thermally induced debromination followed by selective ring-closure to fuse the neighboring benzene moieties via a five-membered ring. The structure of the product has been verified experimentally as well as theoretically...
November 14, 2017: ACS Nano
Ioan Bâldea
Molecular species investigated as possible candidates for molecular photoswitches often toggle between two (low and high conductance) conformations implying skeletal rearrangement, bond breaking, and substantial changes of molecular length. All these represent shortcomings that impede the switching speed and straightforward incorporation in nanodevices. In the present paper we propose a mechanism wherein the photoinduced switching is from a nonplanar conformation to a planar conformation, and involves neither skeletal rearrangement nor bond breaking or significant molecular length changes...
November 14, 2017: Physical Chemistry Chemical Physics: PCCP
Dingyu Hou, Xiaoqing You
Hydrogen abstraction reactions of polycyclic aromatic hydrocarbons (PAH) by H atoms play a very important role in both PAH and soot formation processes. However, large discrepancies up to a few orders of magnitude exist among the literature rate constant values. To increase the reliability of the computed rate constants, it is critical to obtain highly accurate potential energy surfaces. For this purpose, we have investigated the energetics of hydrogen abstraction from benzene and naphthalene using both high level-of-theory quantum chemistry methods and a series of density functional theory (DFT) methods, among which M06-2X/6-311g(d,p) has the best performance with a mean unsigned deviation from the CCSD(T)/CBS calculations of 1...
November 14, 2017: Physical Chemistry Chemical Physics: PCCP
Supaporn Bouson, Atiweena Krittayavathananon, Nutthaphon Phattharasupakun, Patcharaporn Siwayaprahm, Montree Sawangphruk
Although metal-organic frameworks (MOFs) or porous coordination polymers have been widely studied, their antimicrobial activities have not yet been fully investigated. In this work, antifungal activity of copper-based benzene-tricarboxylate MOF (Cu-BTC MOF), which is water stable and industrially interesting, is investigated against Candida albicans, Aspergillus niger, Aspergillus oryzae and Fusarium oxysporum. The Cu-BTC MOF can effectively inhibit the growth rate of C. albicans and remarkably inhibit the spore growth of A...
October 2017: Royal Society Open Science
Mallory LeBlanc, Joseph G Allen, Robert F Herrick, James H Stewart
The Advanced Reach Tool V1.5 (ART) is a mathematical model for occupational exposures conceptually based on, but implemented differently than, the "classic" Near Field/Far Field (NF/FF) exposure model. The NF/FF model conceptualizes two distinct exposure "zones"; the near field, within approximately 1m of the breathing zone, and the far field, consisting of the rest of the room in which the exposure occurs. ART has been reported to provide "realistic and reasonable worst case" estimates of the exposure distribution...
October 31, 2017: International Journal of Hygiene and Environmental Health
Qiang Wang, Ya-Bin Yang, Xue-Qiong Yang, Cui-Ping Miao, Yi-Qing Li, Shi-Xi Liu, Na Luo, Zhong-Tao Ding, Li-Xing Zhao
Eight previously undescribed metabolites including of lovastatin analogues, a pair of diastereoisomers, a cyclopentenone dimer, and three polyketides were isolated from the culture of Aspergillus terreus YIM PH30711. Two types of unprecedented skeletons, benzene-cyclopentanone complex and linear polyketide, and an unusual dimer structure were determined by spectral analysis. Compound, 3α-hydroxy-3,5-dihydromonacolin L showed moderate activity against HMG-CoA reductase, with an inhibition ratio of 34% at the concentration of 50 μM, while lovastatin and dihydromonacolin K ethyl ester presented much stronger activity against HMGR with inhibition rates of 85% and 90% at the concentration of 50 μM, respectively...
November 10, 2017: Phytochemistry
Kun Dai, Qingni Yu, Zhou Zhang, Yuan Wang, Xinming Wang
Non-methane hydrocarbons (NMHCs) are vital to people's health and plants' growth, especially inside a controlled ecological life support system (CELSS) built for long-term space explorations. In this study, we measured 54 kinds of NMHCs to study their changing trends in concentration levels during a 4-person-180-day integrated experiment inside a CELSS with four cabins for plants growing and other two cabins for human daily activities and resources management. During the experiment, the total mixing ratio of measured NMHCs was 423 ± 283 ppbv at the first day and it approached 2961 ± 323 ppbv ultimately...
November 7, 2017: Chemosphere
Marta Stucchi, Federico Galli, Claudia L Bianchi, Carlo Pirola, Daria C Boffito, Franco Biasioli, Valentino Capucci
Volatile and semi volatile organic compounds' concentration have dramatically increased in indoor environments in recent years. UV light promotes titanium dioxide, which oxidises various molecules; however, most of the studies report the degradation of a single VOC. Here, we investigate the photo-oxidation of 17 molecules in mixture to have a realistic test of TiO2 efficacy. We compare P25, a nanometric catalyst, and 1077, a micrometric sample, that poses less health concerns. A proton-transfer-reaction mass spectrometer measured online the concentration of all the pollutants simultaneously...
November 5, 2017: Chemosphere
Simonetta Capone, Maria Tufariello, Angiola Forleo, Valentina Longo, Lucia Giampietruzzi, Antonio Vincenzo Radogna, Flavio Casino, Pietro Siciliano
Cigarette smoking harms nearly every organ of the body and causes many diseases. The analysis of exhaled breath for exogenous and endogenous Volatile Organic Compounds (VOCs) can provide fundamental information on active smoking and insight into the health damage that smoke is creating. Various exhaled Volatile Organic Compounds (VOCs) have been reported as typical of smoking habit and recent tobacco consumption, but to date, no eligible biomarkers have been identified. Aiming to identify such potential biomarkers, in this pilot study we analysed the chemical patterns of exhaled breath from 26 volunteers divided in groups of nonsmokers and subgroups of smokers sampled at different periods of withdrawal from smoking...
November 13, 2017: Biomedical Chromatography: BMC
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