Phosphine fumigation - Time dependent changes in the volatile profile of table grapes.

Industrial and agricultural goods are fumigated in transport containers in order to control pest infestations and to avoid the transmission of alien species. Phosphine is increasingly used prior to the export as fumigant for table grapes, fruit cultures and dried fruits to control active table grapevine insect pests. Less knowledge exists for fumigants about the desorption time of toxic gases and factors that affect the composition of the fumigated good. Therefore, red and white table grapes (´Thompson seedless´, ´Scarlotta´ and ´Flame seedless´) were chosen to represent the allowed group of phosphine fumigated foods and were treated with a concentration of 2000 vpm phosphine (PH3) at different temperatures. In the present study, sorption and desorption behavior of PH3 by table grapes and possible changes in their VOC (volatile organic compounds) profiles were investigated. The PH3 concentration was monitored before and after the fumigation process and was determined under the maximum residue level 0.005 ppm after 35 days. The adsorbed amount of PH3 was not influenced by fumigation parameters. For analysis of the influences on the volatile profile after fumigation, a headspace solid-phase micro-extraction coupled to gas chromatography mass spectrometry (HS-SPME-GC/MS) was used. Small differences in volatile profiles of fumigated and subsequently outgassed table grapes compared to non-fumigated table grapes could be observed. A slight influence on the aldehyde group directly after fumigation could be perceived by a decrease of hex-2-en-1-ol and 1- hexanol in PH3-treated table grapes. The concentrations of both compounds increase again after completion of the desorption process. On the other hand terpenes are not significantly influenced by the fumigation process. Overall these changes are likely to affect table grape aroma characteristics directly after a treatment with PH3 and it could be demonstrated that phosphine alters the volatile profile of fumigated table grapes qualitatively and quantitatively.

Characterization of aluminum, aluminum oxide and titanium dioxide nanomaterials using a combination of methods for particle surface and size analysis.

The application of appropriate analytical techniques is essential for nanomaterial (NM) characterization. In this study, we compared different analytical techniques for NM analysis. Regarding possible adverse health effects, ionic and particulate NM effects have to be taken into account. As NMs behave quite differently in physiological media, special attention was paid to techniques which are able to determine the biosolubility and complexation behavior of NMs. Representative NMs of similar size were selected: aluminum (Al0) and aluminum oxide (Al2O3), to compare the behavior of metal and metal oxides. In addition, titanium dioxide (TiO2) was investigated. Characterization techniques such as dynamic light scattering (DLS) and nanoparticle tracking analysis (NTA) were evaluated with respect to their suitability for fast characterization of nanoparticle dispersions regarding a particle's hydrodynamic diameter and size distribution. By application of inductively coupled plasma mass spectrometry in the single particle mode (SP-ICP-MS), individual nanoparticles were quantified and characterized regarding their size. SP-ICP-MS measurements were correlated with the information gained using other characterization techniques, i.e. transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS). The particle surface as an important descriptor of NMs was analyzed by X-ray diffraction (XRD). NM impurities and their co-localization with biomolecules were determined by ion beam microscopy (IBM) and confocal Raman microscopy (CRM). We conclude advantages and disadvantages of the different techniques applied and suggest options for their complementation. Thus, this paper may serve as a practical guide to particle characterization techniques.

Time-of-flight secondary ion mass spectrometry (ToF-SIMS)-based analysis and imaging of polyethylene microplastics formation during sea surf simulation.

Plastic particles smaller than 5mm, so called microplastics have the capability to accumulate in rivers, lakes and the marine environment and therefore have begun to be considered in eco-toxicology and human health risk assessment. Environmental microplastic contaminants may originate from consumer products like body wash, tooth pastes and cosmetic products, but also from degradation of plastic waste; they represent a potential but unpredictable threat to aquatic organisms and possibly also to humans. We investigated exemplarily for polyethylene (PE), the most abundant constituent of microplastic particles in the environment, whether such fragments could be produced from larger pellets (2mm×6mm). So far only few analytical methods exist to identify microplastic particles smaller than 10µm, especially no imaging mass spectrometry technique. We used at first time-of-flight secondary ion mass spectrometry (ToF-SIMS) for analysis and imaging of small PE-microplastic particles directly in the model system Ottawa sand during exposure to sea surf simulation. As a prerequisite, a method for identification of PE was established by identification of characteristic ions for PE out of an analysis of grinded polymer samples. The method was applied onto Ottawa sand in order to investigate the influence of simulated environmental conditions on particle transformation. A severe degradation of the primary PE pellet surface, associated with the transformation of larger particles into smaller ones already after 14days of sea surf simulation, was observed. Within the subsequent period of 14days to 1month of exposure the number of detected smallest-sized particles increased significantly (50%) while the second smallest fraction increased even further to 350%. Results were verified using artificially degraded PE pellets and Ottawa sand.

Dual beam organic depth profiling using large argon cluster ion beams.

Argon cluster sputtering of an organic multilayer reference material consisting of two organic components, 4,4'-bis[N-(1-naphthyl-1-)-N-phenyl- amino]-biphenyl (NPB) and aluminium tris-(8-hydroxyquinolate) (Alq3), materials commonly used in organic light-emitting diodes industry, was carried out using time-of-flight SIMS in dual beam mode. The sample used in this study consists of a ∽400-nm-thick NPB matrix with 3-nm marker layers of Alq3 at depth of ∽50, 100, 200 and 300 nm. Argon cluster sputtering provides a constant sputter yield throughout the depth profiles, and the sputter yield volumes and depth resolution are presented for Ar-cluster sizes of 630, 820, 1000, 1250 and 1660 atoms at a kinetic energy of 2.5 keV. The effect of cluster size in this material and over this range is shown to be negligible. © 2014 The Authors. Surface and Interface Analysis published by John Wiley & Sons Ltd.

[Examination of visual performance by adaptive optics]. / Untersuchung des Seheindrucks mittels adaptiver Optik.

BACKGROUND: The dependence of visual quality on higher order aberrations (HOA) is highly important for refractive surgery (LASIK) as well as for the correction by vision aids. The use of the adaptive optics (AO) enables the measurement and manipulation of conventional lower order aberrations (defocus, astigmatism) and for HOAs as well. In this work, an Adaptive Optics Visual Simulator is presented that enables one to correct wave-front deformations up to the sixth order of Zernike polynomials, as well as to induce specific aberrations. The subjects observe a TFT monitor, so that a subjective rating of the visual impression is possible, as well as objective measurements. METHODS: Possible applications of such an adaptive optics visual simulator are demonstrated by means of several studies in this survey paper. The main challenge was to investigate the influence of HOAs on the subjective visual impression. Thereby, the following questions have been examined among others: Does the correction of the HOAs lead to an improved visual impression? Are there ways to check the effect of HOAs, what are the effects of single HOAs on the subjective visual impression and what just-noticeable levels do they have? RESULTS: Three studies are presented investigating the impact of HOAs on visus, contrast sensitivity and on vision with glare as well as objective stimulus thresholds of selected HOAs. For example, by using a staircase-procedure it was possible to determine that the objective stimulus threshold for coma has a significantly lower value than the thresholds for astigmatism or trefoil. CONCLUSION: Adaptive optics enables the investigation of effects of HOAs on subjective and objective visual impression. In future, this may result in individualised corrections of refractive errors, which will improve the patient's quality of life.

Monitoring oxidative stress biomarkers in the lipidome: is there a roadmap for "human inspection"?

Oxidative stress is more and more recognized as the underlying motif for a broad variety of diseases including cancer. Medicine faces the paramount task to develop better diagnostic tools and drug treatment prediction models in the future to significantly enhance the quality of life. Special interest will focus on earlystage disease biomarkers and biomarkers that could predict healing success at the earliest time point after the treatment started. The accelerated formation of so-called reactive oxygen species (ROS) is becoming widely regarded as the underlying process associated with many diseases like myocardial infarction, Alzheimer's, Parkinson's and kidney disease, etc. Once generated within cells and tissues, ROS can react with a variety of cellular metabolites like fatty acids, proteins or DNA. This review investigates the possibilities for various oxidized metabolites as well as proteomics, genomics and bioimaging biomarkers to serve as early-stage disease biomarkers or biomarkers for drug treatment success. We also assess the value of a step-by-step or cascade biomarker approach as a new paradigm in medical diagnostics. Examples are given for possible analytical methodology and tools as well as statistical methods that could be applied. Such an approach may straighten the road toward new medical diagnostics and treatment regimes, which ultimately could lead to a significantly enhanced medical service for patients suffering from chronic and debilitating or deadly diseases including cancer. Examples from recent research are given to show the progress and possibilities for the proposed model.

Application of TOF-SIMS with chemometrics to discriminate between four different yeast strains from the species Candida glabrata and Saccharomyces cerevisiae.

We present a TOF-SIMS analysis of the cell surface differences between four yeast strains from two species, Candida glabrata and Saccharomyces cerevisiae (haploid strains BY4742 and BY4741 and the derived diploid BY4743). The study assesses the suitability of TOF-SIMS analysis in combination with statistical methods (principal component analysis, Fisher's discriminant analysis, and cluster analysis) for the discrimination between the four yeast strains. We demonstrate that a combination of these statistical methods identifies 34 ions, from a total data set of 1200, which can be used to distinguish between the four yeasts. The study discusses the assignments of surface cell membrane phospholipids for the identified ions and the resulting differences in the phospholipid pattern between the four yeasts, particularly in relation to ploidy and budding pattern. The method shows that fatty acids, phosphatidylglycerols, phosphatidylethanolamines, phosphatidylserines, and phosphatidylcholines, as well as cardiolipins, are of diagnostic importance.

Chemical basis for inter-colonial aggression in the stingless bee Scaptotrigona bipunctata (Hymenoptera: Apidae).

Inter-colonial aggression was tested using three colonies of Scaptotrigona bipunctata in a natural setting when their nests were moved and by artificial contact between individuals. Examination of the cuticular lipids of individuals from two colonies kept under identical conditions showed clear differences in their cuticular hydrocarbon profiles. The cuticular lipids were a mixture of hydrocarbons (saturated and unsaturated alkanes and alkenes) within the range of C23-C29. The use of multivariate analysis (PCA and discriminant analysis) showed that seven of the identified surface compounds are enough to separate workers from colonies A and B from each other.

A new type of exocrine gland and its function in mass recruitment in the ant Cylindromyrmex whymperi (Formicidae, Cerapachyinae).

Workers of the ant Cylindromyrmex whymperi display mass trail recruitment. Bioassays show that the trail pheromone originates from a unique gland between abdominal sternites 6 and 7. The gland has a hitherto unknown structural organization. Upon leaving the secretory cell, the duct cell widens to form a sclerotized pear-shaped reservoir chamber, lined with multiple duct cells. Each duct thus forms a miniature reservoir for the secretions of each single secretory cells, a novel structural arrangement in exocrine glands of social Hymenoptera.