Determination of levoglucosan from smoke samples using microchip capillary electrophoresis with pulsed amperometric detection

Separation and detection of native anhydrous carbohydrates derived from the combustion of biomass using an electrophoretic microchip with pulsed amperometric detection (PAD) is described. Levoglucosan represents the largest single component of the water extractable organics in smoke particles and can be used to trace forest fires or discriminate urban air pollution sources. Detection of levoglucosan and other sugar anhydrides in both source and ambient aerosol samples is typically performed by gas chromatographic (GC) separation with mass spectrometric (MS) detection. This method is cost, time, and labor intensive, typically involving a multistep solvent extraction, chemical derivatization, and finally analysis by GC/MS. However, it provides a rich wealth of chemical information as the result of the combination of a separation method and MS and exhibits good sensitivity. In contrast, microchip capillary electrophoresis offers the possibility of performing simpler, less expensive, and faster analysis. In addition, integrated devices can be fabricated and incorporated with an aerosol collection system to perform semicontinuous, onsite analysis. In the present report, the effect of the separation potential, buffer pH and composition, injection time, and pulsed amperometric detection parameters were studied in an effort to optimize both the separation and detection of anhydrous sugars. Using the optimized conditions, the analysis can be performed in less than a minute, with detection limits ranging from 22 fmol (16.7 microM) for levoglucosan to 336 fmol (258.7 microM) for galactosan. To demonstrate the capabilities of the device, a comparison was made between GC/MS and microchip electrophoresis using an aerosol source sample generated in a wood-burning chamber. A second example utilizing an ambient aerosol sample illustrates a matrix interference necessitating additional method development for application to samples not dominated by wood smoke.     

Local creep in SnAg3.8Cu0.7 lead-free solder

In this study, local creep of lead-free solder SnAg3.8Cu0.7 has been investigated for the first time by using surface markers prepared by focused ion beam (FIB). The test setup was optimized with respect to the applied shear stresses. Two different microstructures have been investigated at 30°C, 50°C, and 80°C, respectively. A high sensitivity of the steady-state creep rate to the microstructure has been demonstrated. The shear deformation was observed to be inhomogeneous and concentrated in specific areas. Local dislocation bands dominate the solder deformation.     

Effects of Sorbitan Monostearate and Monooleate on the Crystallization and Consistency Behaviors of Cocoa Butter

The crystallization behavior of cocoa butter (CB) is the essential structuration issue in the development of chocolate products. An alternative to modify and control the crystallization patterns of CB in chocolate production is the incorporation of specific emulsifiers in their formulations. In this work, the effects of sorbitan monostearate (SMS) and sorbitan monooleate (SMO) in the crystallization and consistency behaviors as well as on the microstructure of CB were evaluated. CB samples at three different concentrations (0.5, 1.0 and 1.5 % w/w) of SMS and SMO were prepared and their main physical–chemical attributes determined. CB added with 1.5 % of SMS showed the largest effects with a sharp increase in the onset of the crystallization temperature (from 19.3 to 23.8 °C) and doubling the yield value (consistency) of pure cocoa butter. The classic two-step isothermal crystallization behavior and morphology of CB were also modified with the addition of SMS. A possible explanation based on the solubility of SMS in an organic medium and its ability of self-assembling was suggested as a mechanism for SMS performance in CB. SMS was considered as a potential crystal modifier for CB by changing its crystal structure and enhancing its thermal resistance—factors that favor the use of this emulsifier in the production of improved thermally stable chocolates.     

慕尼黑公共交通的设计与运营

The new generation of underground trains travel at a top speed of 80 km/h and are equipped with cutting-edge technology. Current projects rolling stock are equipped with Onboard Fire-Detection and Extinction of fire, viedo-surveillance-system with data communication in parking facilities, on board-TV（passenger information and entertainment） and passenger counting system.     

Diversity of ammonia oxidising bacteria in a vertical flow constructed wetland.

Vertical flow constructed wetlands (VFCWs) with intermittent loading are very suitable for nitrification. Ammonia oxidising bacteria (AOB) are the limiting step of nitration. Therefore the AOB community of a full-scale VFCW, receiving municipal wastewater, was investigated within this study. The diversity of the functional gene encoding the alpha-subunit of the ammonia monooxygenase (amoA), present only in AOB, was assessed by denaturing gradient gel electrophoresis (DGGE). Only very few amoA sequence types dominated the wetland filter substrate; nevertheless a stable nitrification performance could be observed. During the cold season the nitrification was slightly reduced, but it has been shown that the same AOB could be identified. No spatial AOB pattern could be observed within the filter body of the VFCW. The most prominent bands were excised from DGGE gels and sequenced. Sequence analyses revealed two dominant AOB lineages: Nitrosomonas europaea/"Nitrosococcus mobilis" and Nitrosospira. Species of the Nitrosomonas lineage are commonly found in conventional wastewater treatment plants (WWTPs). In contrast, members of the Nitrosospira lineage are rarely present in WWTPs. Our observations indicate that the AOB community in this VFCW is similar to that found in horizontal flow constructed wetlands, but differs from common WWTPs regarding the presence of Nitrosospira.     

Ensuring the reliability of alpha counting

Measuring the alpha flux at the surface of materials from integrated circuits and their packages has been established as a method for more than 2 decades. Largearea low-background counting systems from two vendors were used; these systems operate as proportional counters.^1,2 The results gained from these measurements were used to categorize possible causes of counting errors into groups. Some of these causes are focused on in more detail by the use of examples. It is demonstrated how the cumulative density function (CDF) of a distribution of measured counting rates can be tested graphically for Poisson distribution using two methods. A systematic error is demonstrated and the influence of the duration of the measurements on the detection limit is explained. It is also shown how a suitable bias point can be found for counting tubes. Finally, a schematic of results from alpha counting is presented, and time-dependent changes of these counting rates are stated.     

Chemical Profiles of Scent Gland Secretions in the Cyphophthalmid Opilionid Harvestmen, <Emphasis Type="Italic">Siro duricorius</Emphasis> and <Emphasis Type="Italic">S. exilis</Emphasis>

Gas chromatographic–mass spectrometric analyses of the scent gland secretions of Siro duricorius and S. exilis (Opiliones, Cyphophthalmi, Sironidae) revealed a set of 24 components, comprising a series of saturated and unsaturated methyl ketones (C11–C15) and four naphthoquinones. Whereas the scent gland secretions of S. duricorius, collected in Austria, and S. exilis from USA were qualitatively nearly indistinguishable (with the exception of acetophenone that was specific to S. duricorius), they distinctly differed in their relative quantitative compositions: major components of the secretion of S. duricorius were 7-tridecen-2-one, tridecan-2-one, undecan-2-one, 1,4-naphthoquinone, 6-methyl-1,4-naphthoquinone (tentatively identified only), and 4-chloro-1,2-naphthoquinone. In contrast, in S. exilis a compound tentatively identified as 6-methyl-4-chloro-1,2-naphthoquinone was present in large amounts (in S. duricorius a trace component), whereas undecan-2-one only occurred in minor quantities. Secretion profiles of juveniles and adults (both sexes) of each species showed high correspondence.This is the first report on the chemistry of scent gland secretions of the opilionid suborder Cyphophthalmi. 4-Chloro-1,2-naphthoquinone was identified as a new exocrine product of arthropods, whereas 1,4-naphthoquinone and the tentatively identified 6-methyl-1,4-naphthoquinone are known constituents of exocrine secretions from one species of palpatorid opilionids, Phalangium opilio. In contrast, all ketones identified were new for opilionid scent glands, although similar ketones are characteristic of scent gland secretions of palpatorid genera Leiobunum and Hadrobunus. With regard to the near-basic position of Cyphophthalmi in currently proposed phylogenetic trees of Opiliones, naphthoquinones and ketones from Siro may represent the condition ancestral to the (derived) naphthoquinone- and ketone-rich secretions in phalangid Palpatores.     

SAW filters including one-focus slanted finger interdigital transducers

The present paper describes a new filter type, slanted finger interdigital transducer (SFIT) that allows fast analysis as a precondition for fast optimization. Therefore, filter structure and analysis are especially suitable for optimizing unidirectional SFIT (USFIT) filters. For analysis, a SFIT filter is usually divided into many narrow channels. Every channel is considered to be a subfilter and is analyzed separately. Therefore, the total filter analysis is very time consuming. For reducing computing time, we suggest a one-focus structure. In contrast to conventional SFIT filters, not only the finger and gap widths but also the spaces between transducers of different channels differ by one and the same scaling factor. As a consequence, all prolonged finger edges of both transducers intersect in one point called focus. As a result, the parameters of all subfilters can be calculated from the parameters of only one subfilter by simple frequency scaling. Consequently, the total time for analysis is essentially reduced. However, one-focus SFIT filters with continuous finger edges show a deep minimum within the passband. This problem can be overcome by using stepped one-focus structures.     

Numerical modelling: a tool for better constructed wetland design?

There is a need for a simplified computer-based design tool for subsurface flow constructed wetlands (CWs) which is based on process-based numerical models. Parameters of existing design guidelines and rules have been derived from experiments under specific conditions. Therefore designing CWs using these parameters is limited to these conditions (i.e., temperature, wastewater composition, filter material, etc.). Process-based numerical models describe the main processes in CWs in detail. If the design of CWs is based on these models it will be possible to design CWs for a variety of different boundary conditions and therefore the main limitation of existing design guidelines and rules could be overcome. The use of process-based models is currently limited mainly due to their complexity in structure and use. To make numerical modelling a useful and applicable tool for design, a simplified computer-based design tool that does not require special knowledge of numerical modelling is needed. Additionally, simple models for pre- and post-treatments are also required. Besides allowing designs for various boundary conditions, design tools based on process-based models can also predict the dynamic behaviour of the designed system thus showing e.g., the higher robustness of CWs against fluctuating inflows and peak loads compared to other treatment solutions. Such a tool could increase the quality of CW design and the acceptance and use of CW simulation in practice.