Formaldehyde in hair straightening products: Rapid 1H NMR determination and risk assessment

Despite official regulations, the illegal use of formaldehyde‐containing or releasing hair straightening products has become a popular practice in Europe and high contents of formaldehyde in such products have been reported. In this study, a methodology utilizing ¹H NMR spectroscopy has been developed to measure the concentration of formaldehyde in hair straightening products. For sample preparation, a dilution and alkaline hydrolysis is required. The total formaldehyde content can then be quantified by a distinct peak of the CH₂ group of the methanediol molecule in the δ4.84–4.82 ppm range. The developed methodology was applied for the analysis of 10 hair straightening products. Seven of these products contained detectable amounts of formaldehyde that were higher than the maximum allowed concentration of 0.2%. The formaldehyde content of these products was found to be in the range 0.42–5.83% with an average concentration of 1.46%. The accuracy and reliability of the NMR results were confirmed by the EU reference photometric method. The air formaldehyde concentrations after application of hair straightening products were estimated in ranges 20–423 ppm and 1–18 ppm (for 1 and 24 m³ salon volume). A probabilistic exposure estimation using Monte Carlo simulation found the average formaldehyde concentration to be 6 ppm (standard deviation 15 ppm). All exposure scenarios considerably exceeded the safe level of 0.1 ppm. Our findings confirmed that the risk of cosmetic formulations with formaldehyde above 0.2% is not negligible, as these products may facilitate considerable exposure of formaldehyde for consumers especially for salon workers.     

Micromachined Loop Antennas on Low Resistivity Silicon Substrates

The integration of K-band (20-40 GHz) full wavelength square wire- and slot-loop antennas on low resistivity (11-70 Omegacm) silicon substrates is addressed. By the use of polymer or silicon oxide/nitride membranes to support the slot or wire loop over micromachined trenches the efficiency of the antennas is enhanced while the majority of the bulk silicon within the aperture of the antenna is preserved to enable the integration of active devices. A 3.6times3.6 mm² large slot loop antenna chip with 200 mum micromachined trench width yields 1.5 dBi gain at 29.5 GHz, while 1.0 dBi gain is obtained at 24 GHz for a wire loop antenna on a 4.5times4.5 mm² large chip with 360 mum wide trenches     

果胶在水果制品和酸奶中的增稠作用

<正> 水果酸奶在乳制品中占有主导地位,是液态酸奶中品种最为繁多的产品。另一类含有水果的乳制品是分层水果乳制品,在市场上亦占有颇高的比例。在分层水果乳制品中,水果制品被置于酸奶与农家干酪或凝乳的下面,而不同的水果制品亦可各自分成独立的间     

Clouds and the Earth's Radiant Energy System (CERES): algorithmoverview

The Clouds and the Earth's Radiant Energy System (CERES) is part of NASA's Earth Observing System (EOS), CERES objectives include the following. (1) For climate change analysis, provide a continuation of the Earth Radiation Budget Experiment (ERBE) record of radiative fluxes at the top-of-the-atmosphere (TOA), analyzed using the same techniques as the existing ERBE data. (2) Double the accuracy of estimates of radiative fluxes at TOA and the Earth's surface. (3) Provide the first long-term global estimates of the radiative fluxes within the Earth's atmosphere. (4) Provide cloud property estimates collocated in space and time that are consistent with the radiative fluxes from surface to TOA. In order to accomplish these goals, CERES uses data from a combination of spaceborne instruments: CERES scanners, which are an improved version of the ERBE broadband radiometers, and collocated cloud spectral imager data on the same spacecraft. The CERES cloud and radiative flux data products should prove extremely useful in advancing the understanding of cloud-radiation interactions, particularly cloud feedback effects on the Earth's radiation balance. For this reason, the CERES data should be fundamental to the ability to understand, detect, and predict global climate change. CERES results should also be very useful for studying regional climate changes associated with deforestation, desertification, anthropogenic aerosols, and ENSO events. This overview summarizes the Release 3 version of the planned CERES data products and data analysis algorithms. These algorithms are a prototype for the system that will produce the scientific data required for studying the role of clouds and radiation in the Earth's climate system     

Das feuchtigkeitstechnische Verhalten hölzerner Außenbauteile in Theorie und Praxis

Part 1 described the effect of sorption behaviour of layers of wall units on construction calculations. The present paper is a report on practical experiments describing the moisture behaviour of layers of wall units. The moisture behaviour of wooden exterior structural units depends on changes in humidity due to hygroscopicity and is determined by climate conditions indoors and outdoors. Moisture in wooden or wood-based layers is exchanged between all boundary layers by means of diffusion, sorption and condensation. Exchange intensity can be influenced by the construction of the unit, e.g. by the structure of layers, by the effects of break-throughs, type and arrangement of vapour barriers, aeration with the outer air through ventilation zones, the position of insulating layers and by facade preservation. Another influencing factor is the position of the structural unit in relation to solar radiation.     

Diskontinuierliche Fraktionierung zur Auftrennung eines Vielstoffgemisches

Discontinuous Fractionation for the Separation of a Multicomponent Mixture The economics of several continuous and discontinuous fractionation processes for the separation of a mixture containing fatty acids of the carbon chain lengths C12, C14, C16 and C18 are investigated depending on the plant throughput. The calculations show, that in case of the fatty acid mixture being discussed the batch-fractionation is an economic alternative to continuous fractionation processes for throughputs of less than 500 tons per annum. For mixtures consisting of more components batch-fractionation is an attractive process even at higher throughputs. With regard to high yield and high purity of the single fractions the batch-column should be operated with constant purity in the distillate.