Comparison of antifungal activity of essential oils of clove, lemongrass and thyme for natural preservation of dried apricots

Currently, the majority of fresh apricots destined for the production of dried apricots undergo sulphur oxide fumigation before drying to protect the fruit against fungal spoilage. To eliminate the use of sulphite, packaging assisted with essential oil is a promising strategy to increase shelf-life of dried apricots since it does not impact its flavor characteristics. In this study, three essential oils were selected: clove, lemongrass and thyme. They were screened for antifungal activity against Eurotium spp. with different methods: micro- and macro-dilution and agar-diffusion. Growth/no-growth data were used to develop models for all three methods. Clove exerted the strongest antifungal activity with an inhibitory concentration of 0.075%, 0.035% and 0.05% through respectively micro-dilution, macro-dilution and agar diffusion. For thyme the following values were obtained: 0.775%, 0.070% and 0.100%. This means that the antifungal activity of thyme is 10 times lower in micro-dilution and 2 times lower in macro-dilution and agar diffusion compared to clove. Through micro-dilution, lemongrass was found to have the second highest antifungal activity (0.25%). When used in the volatile atmosphere of dried apricots and in macro-dilution, the antifungal activity of lemongrass was the lowest, with respective values of > 0.200% and 0.105% for G/NG prediction.

Green Shipping—Multifunctional Marine Scrubbers for Emission Control: Silencing Effect

Scrubber systems abate the sulphur oxide emissions of engines when cheap fuel oils that are high in sulphur content are employed as combustibles. However, the ships with these voluminous devices installed on board is space demanding. This work analyses the feasibility of incorporating the acoustic abatement of the exhaust gas noise functionality into the scrubber design to provide a combined scrubber–silencer system. For this purpose, a finite element analysis is performed on a simple expansion chamber, which is assessed using both analytical and experimental data. The transmission loss is the acoustic parameter chosen in this work. The numerical model depicts a good correlation with the transmission loss measured on a model scale scrubber. Finally, scrubber geometry modifications alter the transmission loss, changing and/or enhancing its featuring. These abilities indicate the feasibility to confer to scrubber silencing effects.

Mechanism of Acidification that Progresses in Library Collections of Books Made of Alkaline Paper

Acidification mechanisms of paper were examined, studying 120 pairs of identical copies of books published from 1971 to 2010 housed in two Japanese university libraries. The pH at the edges of the alkaline paper lowered from 7.5 to 6.4 after 5–10 years and to 5.8 after 10–15 years after publication. The pH bottomed at 5.4 at the edges and at 7.0 in the centre of the sheet. Acid paper showed higher pH at the edges than in the centre of the sheet. The edge pH of the alkaline paper of books stored on an above-ground floor was lower due to more exposure to incoming open air with pollutants compared to paper stored in the basement. Elemental analysis suggested nitrogen oxide deposition, but could not prove sulphur oxide deposition at the edges of the paper. The position-dependent acidification is presumed to relate to the deposition tendency of air pollutants contained in open air, and accordingly the edge pH dropped dramatically. In the 1980s, alkaline paper was increasingly used in the production of books, and it was assumed that no more book acidification was to occur; however, this study concludes that even in alkaline paper, acidification processes will take place over time.

Particulate Matter Emission Reduction from Marine Diesel Engines by Electrohydrodynamic Methods

Particulate matter (PM) and gaseous compounds (SO2, NOx, VOC) emitted by diesel engines causes serious global environmental problems and health impact. Despite numerous evidences about the harmfulness of diesel particles, the PM emission by diesel engines used by ships, cars, agricultural machines, or power generators is still unregulated, and the efficient removal of PM from diesel exhausts is still the major technological challenge. In order to comply with the International Maritime Organization regulation, the NOx emission is reduced by using selected catalytic reactor, and sulphur oxide emission has been reduced by using fuels of low sulphur content. However, both of those measures cannot be used for the reduction of PM emission produced during combustion of marine fuels. The lack of appropriate regulations results from insufficiently developed technology, which could remove those particles from exhaust gases. Conventional scrubbers currently available on the market remove only sulphur oxide with required collection efficiency, but the collection efficiency for PM2.5 is below 50%. The article discusses the technical means used for the removal of PM from marine diesel engines via applying electrohydrodynamic methods, in particular electrostatic agglomeration, as a method of nanoparticles coagulation to larger agglomerates, which could operate in two-stage electrostatic precipitation systems, and electrostatic scrubbers, which remove particles by electrically charged water droplets. The experimental results were obtained for a 2-stroke 73 kW diesel engine fuelled with marine gas oil (MGO). The agglomerator allowed increasing the collection efficiency from diesel exhausts for PM2.5 particles by about 12%, compared to electrostatic precipitator operating without agglomerator, and the total mass collection efficiency was above 74%. The collection efficiency of electrostatic scrubber was higher than 95wt.%. The advantage of using the electrostatic scrubber is that it can also reduce the SO2 emission by more than 90%, when HFO is used.

Reassessment of the environmental impacts of sulphur oxide emissions from power stations

It is a deeply entrenched belief that emissions of sulphur dioxide into the atmosphere are harmful to the environment, and that sulphur compounds should be removed from the gaseous wastes before discharge. The difficulties with this view are summarised. Extensive work in both North America and Europe has failed to demonstrate any of the early claims for impacts such as forest death. The claims for health effects seem unduly conservative and not supported by reliable data. There are even negative impacts from reducing sulphur emissions. Claims for high external costs associated with coal-fired power generation in South Africa are the result of arithmetic errors. The installation of flue-gas desulphurisation on the latest Eskom power station, Kusile, is shown to be completely unsustainable in the light of the minimal benefits that the considerable costs will bring.

The Effect of Sulphur Dioxide on the Adsorption Properties of Activated Carbon towards Chloropicrin

Sulphur dioxide is believed to be adsorbed on activated carbons in both physically and chemically bound states. Sulphuric acid and a variety of oxygenated and hydrated sulphur oxide species are believed to be present on humidified carbons exposed to sulphur dioxide. Samples of ASC/T impregnated carbons were exposed to sulphur dioxide mixtures in humid air at 80% RG and 22°C. The sulphur dioxide-loaded carbons were then exposed to chloropicrin challenge at 5 mg/dm3 in air at 80% RH and 22°C and the chloropicrin breakthrough times measured. A relationship was found between the extra mass gain of the carbons (due to oxygen and water) with increasing sulphur dioxide loading, as predicted by other workers. The effect of sulphur dioxide loading on the chloropicrin breakthrough times was a gradual reduction to about one-third the time for unexposed carbon, with an adsorbed mass of sulphur dioxide equal to ca. 10% of the carbon mass in a 20 mm bed-depth filter.