Coffee and cancer risk,epidemiological evidence,and molecular mechanisms

Although early studies suggested that coffee consumption might increase risk of some cancers, more comprehensive epidemiological and experimental data now generally indicate either neutral or beneficial effects. In this review, we summarize the current evidence for associations between breast, prostate, colorectal, and liver cancers and the consumption of coffee, and discuss the experimental evidence for potential chemopreventive mechanisms of coffee and coffee constituents. The epidemiological evidence consistently indicates that coffee protects against liver cancer, and also point toward protective effects for risk of colorectal cancers (with relative risks of 0.50 (95% CI: 0.42–0.59) and 0.83 (95% CI: 0.75–0.92), respectively, in the most recent meta‐analyses). There seems to be no association between the overall risk of breast and prostate cancer and coffee intake. However, for subgroups such as postmenopausal breast cancers, advanced prostate cancers, and breast and prostate cancer survivors, an inverse association with coffee intake is indicated. Potential mechanisms for chemopreventive effects of coffee phytochemicals includes inhibition of oxidative stress and oxidative damage, regulation of DNA repair, phase II enzymatic activity, apoptosis, inflammation, as well as having antiproliferative, antiangiogenetic effects and antimetastatic effects. The experimental evidence for effects of coffee and coffee constituents on each of these processes is discussed.     

Electron-beam treatment of aromatic hydrocarbons that can be air-stripped from contaminated groundwater. 2. Gas-phase studies

The electron-beam (EB) degradation of volatile aromatics (benzene, toluene, ethylbenzene, xylenes: BTEX) in groundwater strip gas, which in the present work has been modeled by the introduction of the desired aromatic(s) to a stream of air or another gas, such as oxygen, is initiated essentially by the addition of *OH radicals to the aromatic ring, giving rise to hydroxycyclohexadienyl radicals, which form the corresponding peroxyl radicals upon addition of oxygen. As studied in some detail with benzene as a BTEX representative, various reactions of these lead to numerous oxidation products in a cascade of reactions, including the decomposition of products under the prevailing conditions of high turnover of the initial aromatic. Importantly, hydroxycyclohexadienylperoxyl radical formation is partly reversible, and the reactions of the hydroxycyclohexadienyl radicals, which thus have a significant presence in these systems, must therefore also be taken into consideration. In the gas phase, in contrast to the aqueous phase (see Part 1), the reactions of the hydroxycyclohexadienyl radicals lead to oligomeric products that appear to contribute, in addition to ionic clusters, to nucleation for the aerosols observed. Various nitrated products, among them nitrophenols, are observed when air is used for the stripping. However, these studies did not clear the pilot plant stage, since BTEX degradation using a bioreactor carried out in parallel was so successful that the EB technology was judged to be noncompetitive. As for the latter, expensive equipment consisting of a stripper, the EB machine, and an aerosol precipitator would be required. The condensed aerosols are biorefractory and would require further treatment for detoxification.     

Student/Professor Ethics In Engineering Academia

This paper considers the components which constitute a safe, ethical academic environment in which students can explore the intricacies of engineering technology and engineering science. The concerns of the undergraduate and the graduate student are presented and contrasted, from both the perspective of the student and the faculty.     

Detection of electrically charged soot particles in laminar premixed flames

A particle mass spectrometer has been used to investigate the formation of electrically charged species and soot particles in laminar premixed flames. The mass range was from 600–6 × 10⁵ amu and extends from high molecular hydrocarbons to soot particles of 10 nm diameter. The flames were stabilized on cooled porous plate burners. Acetylene/oxygen flames were investigated at low pressure (30 mbar), and ethylene/air flames were investigated at atmospheric pressure. Soot particles could only be detected in flames showing yellow luminosity, i.e. above the critical C/O-ratio for soot formation. Both positively and negatively charged particles were found, the positive charge dominating in the low pressure acetylene/oxygen flames, the negative charge dominating in the atmospheric ethylene/air flames. With the assumption of spherical shape and constant density, the mass spectra were converted to size spectra. Usually, they show a multiple peak structure which is somewhat difficult to interpret. There are indications that particles may carry multiple (1–2) charges, and also that particles of different types may coexist beside polyaromatic and polyhedral species in the early stage of particle inception.     

New development in flow‐through pressure‐swing frequency response method for mass‐transfer study: Ethane in ZIF‐8

A new pressure‐swing frequency response (PSFR) method has been developed to study mass transfer in adsorption systems as a function of temperature and pressure, from ?70 to 180°C, and up to 7 bar. New in‐phase and out‐of‐phase functions have been derived for the PSFR in a general way to allow information extracted from it independent of whether the system is operated in a batch volume swing or a flow‐through pressure swing mode. A new mathematical model that considers distribution of diffusion rates has been introduced to account for diffusive transport in heterogeneous samples. Numerical simulation results have shown that a single rate diffusion model works well when heterogeneity can be described by a normal distribution, but not for asymmetrically bimodal distributions. As a test reference system, the transport of ethane in ZIF‐8 was investigated at different pressures and temperatures using the new PSFR method. The mass transfer was found to be dominated by micropore diffusion. Diffusivity was found to be weakly dependent on pressure or loading, but quite strongly dependent on temperature. The results agree very well with our independent batch volume frequency response technique experiments. © 2016 American Institute of Chemical Engineers AIChE J, 63: 1077–1090, 2017     

In Vitro Exposure Systems and Bioassays for the Assessment of Toxicity of Nanoparticles to the Human Lung

The rapid development of nanotechnology requires the production of nanoparticles which are found in numerous novel products. To reduce the number of animal tests during the assessment of lung toxicity of airborne nanoparticles in vitro exposure systems and lung specific bioassays have been developed. The reproducible application of bioassays for exposure of lung cells at the air-liquid interface promises a higher efficiency and cost reductions in toxicological testing. Despite significant progress of the exposure technology and fundamentals of bioassays a stringent validation of the in vitro versus in vivo tests is still lacking.

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Zusammenfassung:  Die schnelle Entwicklung der Nanotechnologie erfordert die Produktion von Nanopartikeln, die mittlerweile in zahlreichen neuen Produkten eingesetzt werden. Um die Anzahl der Tierversuche bei der Prüfung auf Lungentoxizit?t zu vermindern, wurden in vitro Expositionsverfahren und lungenspezifische Bioassays entwickelt. Die reproduzierbare Anwendung von Bioassays, die auf der Exposition von Lungenzellen an der Luft-Flüssigkeitsgrenzschicht beruhen, verspricht Effizienzgewinne und Kostenminderung bei toxikologischen Tests. Trotz deutlicher Fortschritte bei der Expositionstechnologie und bei den Grundlagen der Bioassays fehlt noch immer eine stringente Validierung der in vitro Tests gegenüber den in vivo Verfahren.

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Received: February 7, 2008; accepted: February 13, 2008     

In-vitro cell exposure studies for the assessment of nanoparticle toxicity in the lung—A dialog between aerosol science and biology

The introduction of engineered nanostructured materials into a rapidly increasing number of industrial and consumer products will result in enhanced exposure to engineered nanoparticles. Workplace exposure has been identified as the most likely source of uncontrolled inhalation of engineered aerosolized nanoparticles, but release of engineered nanoparticles may occur at any stage of the lifecycle of (consumer) products. The dynamic development of nanomaterials with possibly unknown toxicological effects poses a challenge for the assessment of nanoparticle induced toxicity and safety.In this consensus document from a workshop on in-vitro cell systems for nanoparticle toxicity testing¹ an overview is given of the main issues concerning exposure to airborne nanoparticles, lung physiology, biological mechanisms of (adverse) action, in-vitro cell exposure systems, realistic tissue doses, risk assessment and social aspects of nanotechnology. The workshop participants recognized the large potential of in-vitro cell exposure systems for reliable, high-throughput screening of nanoparticle toxicity. For the investigation of lung toxicity, a strong preference was expressed for air–liquid interface (ALI) cell exposure systems (rather than submerged cell exposure systems) as they more closely resemble in-vivo conditions in the lungs and they allow for unaltered and dosimetrically accurate delivery of aerosolized nanoparticles to the cells. An important aspect, which is frequently overlooked, is the comparison of typically used in-vitro dose levels with realistic in-vivo nanoparticle doses in the lung. If we consider average ambient urban exposure and occupational exposure at 5 mg/m³ (maximum level allowed by Occupational Safety and Health Administration (OSHA)) as the boundaries of human exposure, the corresponding upper-limit range of nanoparticle flux delivered to the lung tissue is 3×10^?5–5×10^-3 μg/h/cm² of lung tissue and 2–300 particles/h/(epithelial) cell. This range can be easily matched and even exceeded by almost all currently available cell exposure systems.The consensus statement includes a set of recommendations for conducting in-vitro cell exposure studies with pulmonary cell systems and identifies urgent needs for future development. As these issues are crucial for the introduction of safe nanomaterials into the marketplace and the living environment, they deserve more attention and more interaction between biologists and aerosol scientists. The members of the workshop believe that further advances in in-vitro cell exposure studies would be greatly facilitated by a more active role of the aerosol scientists. The technical know-how for developing and running ALI in-vitro exposure systems is available in the aerosol community and at the same time biologists/toxicologists are required for proper assessment of the biological impact of nanoparticles.