Energy policies avoiding a tipping point in the climate system

Paleoclimate evidence and climate models indicate that certain elements of the climate system may exhibit thresholds, with small changes in greenhouse gas emissions resulting in non-linear and potentially irreversible regime shifts with serious consequences for socio-economic systems. Such thresholds or tipping points in the climate system are likely to depend on both the magnitude and rate of change of surface warming. The collapse of the Atlantic thermohaline circulation (THC) is one example of such a threshold. To evaluate mitigation policies that curb greenhouse gas emissions to levels that prevent such a climate threshold being reached, we use the MERGE model of Manne, Mendelsohn and Richels. Depending on assumptions on climate sensitivity and technological progress, our analysis shows that preserving the THC may require a fast and strong greenhouse gas emission reduction from today's level, with transition to nuclear and/or renewable energy, possibly combined with the use of carbon capture and sequestration systems.     

Substituting non-natural agents in UV-protection cream by a mixture of clay with Ganoderma pfeifferi extract

To investigate the potential of substituting non-natural agents in sunscreen, mixtures of some clays with Ganoderma pfeifferi extract were examined in regard to their protection abilities against ultraviolet (UV) radiation in the wavelength range 250–400 nm. Some mixtures showed remarkably high UV-protection potential in comparison with corresponding clay cream devoid of the fungal extract. Depending on interlayer charge of the dominant clay mineral contained in the clays, the interaction between the fungal extract and the clay mineral played a key role in the UV-protection ability of the mixtures. The optimal clay in the mixture with the G. pfeifferi extract for sunscreens was dominated by expandable clay minerals with low interlayer charge.     

Further advances toward the development of a direct heating solar thermal chemical reactor for the thermal dissociation of ZnO(s)

We designed, built and experimentally tested a solar thermal chemical reactor for producing Zn from ZnO(s). We describe the salient features of the reactor concept, the design process itself, and initial experimental results from testing the reactor under solar conditions for both the thermal reduction of ZnO(s) and the carbothermal reduction of the oxide. The reactor operated reliably for more than 100 h. Reactor cavity temperatures reached 2000 K. For the carbothermal reduction of ZnO(s), the solid product was Zn with a purity exceeding 95 mol%. For this reaction, we report reactor and process efficiencies versus cavity temperature. Average values were as high as 14% and 12% respectively. There is an optimal operating temperature and feed condition for these efficiencies: the positive effect of high reaction rates at high temperatures must be balanced against high radiation losses from the reactor at high temperatures. At the operating conditions leading to the highest efficiencies, we produced 1.5 moles of Zn for each mole of consumed carbon. Although the reactor operated mechanically as expected for the thermal reduction of ZnO(s), we were not yet able to obtain high Zn yields.     

Risk ranking of bioaccessible metals from fly ash dissolved in simulated lung and gut fluids

Power plant fly ash from two fuels, coal and a mixture of coal and shredded tires, were evaluated for trace metal solubility in simulated human lung and gut fluids (SLF and SGF, respectively) to estimate bioaccessibility. The proportion of bioaccessible to total metal ranged from zero (V) to 80% (Zn) for coal-derived ash in SLF and from 2 (Th) to 100% (Cu) for tire-derived fly ash in SGF. The tire-derived ash contained much more Zn. However, Zn ranked only 5th of the various toxic metals in SGF compared with international regulations for ingestion. On the basis of total concentrations, the metals closestto exceeding limits based on international regulations for inhalation were Cr, Pb, and Al. On dissolution in SLF, the most limiting metals were Pb, Cu, and Zn. For metals exposed to SGF there was no relative change in the top metal, Al, before and after dissolution but the second-ranked metal shifted from Pb to Ni. In most cases only a proportion of the total metal concentrations in either fly ash was soluble, and hence bioaccessible, in either biofluid. When considering the regulatory limits for inhalation of particulates, none of the metal concentrations measured were as hazardous as the fly ash particulates themselves. However, on the basis of the international ingestion regulations for Al, the maximum mass of fly ash that could be ingested is only 1 mg per day (10 mg based on bioaccessibility). It is possible that such a small mass could be consumed by exposed individuals or groups.     

An event-related analysis of awakening reactions due to nocturnal church bell noise

The sleep disturbing effects of nocturnal ambient non-traffic related noises such as bell strokes emitted from church bell towers on nearby residents are presently unknown. Nonetheless, this specific noise source is suspected to cause sleep disturbances in a small but qualified minority of people living in the vicinity of the bell towers that throughout the night indicate the time with bell ringings. A field study was carried out to elucidate whether acoustic properties of such bell strokes relate to awakening and to provide event-related exposure-effect functions between acoustical predictors and awakening probability. Awakening reactions were determined in 27 voluntary subjects, measured in their home setting for four consecutive nights with ambulatory polysomnography (PSG) and concurrent acoustic recordings in- and outside the dwelling. Results indicate that the bell ringing events increase awakenings in a similar fashion as has previously been reported with transportation noise events and that awakening probability first and foremost depends on maximum sound pressure level of an event. The number of bell strokes and the personal variables gender, age, and noise sensitivity did not influence awakening probability significantly. Awakening probability by tendency increased with elapsed time after sleep onset, and was decreased during slow wave sleep and REM sleep compared to S2 sleep. The results suggest that a reduction of the maximum sound pressure level or an interruption of ringings during nighttime might reduce awakenings. The determined exposure-effect relationships are compared with similar functions for impulsive noise and transportation noise, more specifically, aircraft noise. The paper concludes with a few considerations regarding nighttime noise regulation.     

Specific detection and determination of azide in wine

Summary In view of false-positive results obtained with the azide-detection method based on complex-formation with ferric ions, a specific liquid-chromatographic azide determination was adapted for the analyses of wine. The samples are distilled free of alcohol under alkaline conditions and acidified, and a new distillate is collected. The distillate is buffered (pH 4.7) and treated with 3,5-dinitrobenzoylchloride and the derivative thus formed is detected and determined by HPLC.

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Spezifischer Nachweis und Bestimmung von Azid in Wein

Zusammenfassung Die Detektion von Azid in Wein mit Hilfe der Komplexbildung mit Fe(III)-ionen kann zu falsch-positiven Ergebnissen führen. Aus diesem Grunde wurde eine beschriebene HPLC-Methode zur Bestimmung von Azid für die Analyse von Weinproben abgewandelt. Die Proben werden dabei in alkalischem Milieu durch Destillation vom Alkohol befreit, der Rückstand wird angesäuert und ein neues Destillat gesammelt. Davon wird ein Aliquot, nach Einstellen des pH-Wertes mittels Puffer (4,7), mit 3,5-Dinitrobenzoylchlorid versetzt und das gebildete Derivat flüssigchromatographisch bestimmt.

     

The impact of carotid plaque screening on motivation for smoking cessation.

Showing smokers their own atherosclerotic plaques might increase motivation for smoking cessation, since they underestimate their own risk for smoking-related diseases. To assess the feasibility and optimal processes of studying the impact of carotid atherosclerotic plaque screening in smokers, we enrolled 30 daily cigarette smokers, aged 40-70 years, in an observational pre-post pilot study. All smokers underwent smoking cessation counseling, nicotine replacement therapy, a carotid ultrasound, an educational tutorial on atherosclerosis, baseline and 2-month motivation to change assessment, and assessment of smoking cessation at 2 months. Participants had a mean smoking duration of 34 years (SD = 7). Carotid plaques were present in 22 smokers (73%). Between baseline and 2 months after plaque screening, motivation for smoking cessation increased from 7.4 to 8.4 out of 10 (p = .02), particularly in those with plaques (7.2 to 8.7, p = .008). At 2 months, the smoking quit rate was 63%, with a quit rate of 73% in those with plaques vs. 38% in those without plaques (p = .10). Perceived stress, anxiety, and depression did not increase after screening. 96% of respondents answered correctly at least 80% of questions regarding atherosclerosis knowledge at baseline and after 2 months. In conclusion, studying the process of screening for carotid plaques for the purpose of increasing motivation for smoking cessation, in addition to counseling and drug therapy for smoking cessation in long-term smokers, appears feasible. The impact of carotid plaque screening on smoking cessation should be examined in larger randomized controlled trials with sufficient power to assess the impact on long-term smoking cessation rates.     

Potentiometric immunoassay with quantum dot labels

Potentiometric sensors based on polymer membrane electrodes, if properly optimized, are useful for measurements at trace levels. The expected independence of the electrochemical signal of the sample size makes them extremely attractive for measurements in small volumes. Here, we report on electrodes for the potentiometric detection of cadmium ions that reach a detection limit of 6 nM and utilize a Na(+)-selective electrode as pseudoreference in order to facilitate measurements in 150-microL samples. A potentiometric immunoassay of mouse IgG is performed via CdSe quantum dot labels on a secondary antibody according to a sandwich immunoassay protocol in a microtiter plate format. The CdSe quantum dots are found to be easily dissolved/oxidized in a matter of minutes with hydrogen peroxide, allowing us to maintain the pH at a near-neutral value. The potentiometric protein immunoassay exhibits a log-linear response ranging from 0.15 to 4.0 pmol of IgG, with a detection limit of <10 fmol in 150-microL sample wells.     

A Chiral Disulfoxide Ligand for the Efficient Rhodium‐Catalyzed 1,2‐Addition of Arylboroxines to N‐Tosylarylimines

Enantiomerically pure diarylmethylamines are important building blocks in active pharmaceutical ingredients. Herein, we report a rhodium precatalyst with a chiral disulfoxide ligand that effects the 1,2‐addition of arylboroxines to aromatic imines to give high yields and high enantioselectivities of these products. The present paper describes a system that is very simple, where the ease of synthesis of the chiral ligand is combined with low catalyst loadings and reaction conditions that do not need any additives or external base.