Resistance of human hair cuticle after a shaking process in wet conditions: comparison between Chinese and Caucasian hair

Hair cuticle is the first protection shield of hair against external aggressions such as daily combing or brushing that induce friction, mechanical stress leading to ageing process. The identification of alterations of the hair surface induced by shaking process of various hair fibres, such as virgin and chemically treated Chinese and Caucasian hair, sheds some light on some specific features, e.g. Chinese cuticle is torn out in smaller particles than Caucasian, which seems to be related to geometrical rather than ethnic reasons. The present work also shows that two geometrical parameters of human hair, the inter‐scale distance and the scale angle are directly linked to fibre dimensions, regardless of ethnic origin. Representative of hair with an average larger cross‐sectional area, Chinese hair shows a slightly smaller inter‐scale distance as well as a higher scale angle. On the other hand, Chinese hair cuticle seems to be more sensitive to chemical treatment than Caucasian hair, at least for straightening treatment taken here as an example. Such an approach can be of interest in designing cosmetic products more suited to specific needs of human hair.     

Pyrrolizidine alkaloids in honey: comparison of analytical methods

Pyrrolizidine alkaloids (PAs) are a structurally diverse group of toxicologically relevant secondary plant metabolites. Currently, two analytical methods are used to determine PA content in honey. To achieve reasonably high sensitivity and selectivity, mass spectrometry detection is demanded. One method is an HPLC-ESI-MS-MS approach, the other a sum parameter method utilising HRGC-EI-MS operated in the selected ion monitoring mode (SIM). To date, no fully validated or standardised method exists to measure the PA content in honey. To establish an LC-MS method, several hundred standard pollen analysis results of raw honey were analysed. Possible PA plants were identified and typical commercially available marker PA-N-oxides (PANOs). Three distinct honey sets were analysed with both methods. Set A consisted of pure Echium honey (61-80% Echium pollen). Echium is an attractive bee plant. It is quite common in all temperate zones worldwide and is one of the major reasons for PA contamination in honey. Although only echimidine/echimidine-N-oxide were available as reference for the LC-MS target approach, the results for both analytical techniques matched very well (n = 8; PA content ranging from 311 to 520 μg kg(-1)). The second batch (B) consisted of a set of randomly picked raw honeys, mostly originating from Eupatorium spp. (0-15%), another common PA plant, usually characterised by the occurrence of lycopsamine-type PA. Again, the results showed good consistency in terms of PA-positive samples and quantification results (n = 8; ranging from 0 to 625 μg kg(-1) retronecine equivalents). The last set (C) was obtained by consciously placing beehives in areas with a high abundance of Jacobaea vulgaris (ragwort) from the Veluwe region (the Netherlands). J. vulgaris increasingly invades countrysides in Central Europe, especially areas with reduced farming or sites with natural restorations. Honey from two seasons (2007 and 2008) was sampled. While only trace amounts of ragwort pollen were detected (0-6.3%), in some cases extremely high PA values were detected (n = 31; ranging from 0 to 13019 μg kg(-1), average = 1261 or 76 μg kg(-1) for GC-MS and LC-MS, respectively). Here the results showed significantly different quantification results. The GC-MS sum parameter showed in average higher values (on average differing by a factor 17). The main reason for the discrepancy is most likely the incomplete coverage of the J. vulgaris PA pattern. Major J. vulgaris PAs like jacobine-type PAs or erucifoline/acetylerucifoline were not available as reference compounds for the LC-MS target approach. Based on the direct comparison, both methods are considered from various perspectives and the respective individual strengths and weaknesses for each method are presented in detail.     

On the mechanism of Ag exudation during internal oxidation

Internal oxidation experiments under different oxidation conditions focusing on the characteristics of noble metal exudation are presented together with finite element method (FEM) simulation calculations of the build-up of internal stresses. In a high-temperature bending test with a fully oxidized Ag–SnO₂–In₂O₃ sample stress states that were comparable with those occurring during internal oxidation were generated, but exudation of Ag was not observed. From further targeted internal oxidation experiments in combination with FEM simulation calculations of internal stress distributions it can be concluded that internal stresses play a minor role in the occurrence of noble metal exudation. It is suggested that exudation occurs due to a gradient in the chemical potential of the noble metal. The potential gradient is a consequence of the concentration gradient of inward diffusing oxygen. The influence of the oxygen-induced driving force on the development of microstructure considering internal and external noble metal layers is discussed.     

Feeding Deterrence and Detrimental Effects of Pyrrolizidine Alkaloids Fed to Honey Bees (<Emphasis Type="Italic">Apis mellifera</Emphasis>)

Recent studies have shown the occurrence of plant derived pyrrolizidine alkaloids (PAs) in retail honeys and pollen loads, but little is known about how these compounds influence the fitness of foraging honey bees. In feeding experiments, we tested a mix of tertiary PAs and the corresponding N-oxides from Senecio vernalis, pure monocrotaline, and 1,2-dihydromonocrotaline in 50% (w/w) sucrose solutions. The bees were analyzed chemically to correlate the observed effects to the ingested amount of PAs. PA-N-oxides were deterrent at concentrations >0.2%. 1,2-Unsaturated tertiary PAs were toxic at high concentrations. The observed PAs mortality could be linked directly to the presence of the 1,2-double bond, a well established essential feature of PA cytotoxicity. In contrast, feeding experiments with 1,2-dihydromonocrotaline revealed no toxic effects. Levels of less than 50 μg 1,2-unsaturated tertiary PAs per individual adult bee were tolerated without negative effects. PA-N-oxides fed to bees were reduced partially to the corresponding tertiary PAs. Unlike some specialized insects, bees are not able to actively detoxify PAs through N-oxidation. To gain insight into how PAs are transmitted among bees, we tested for horizontal PA transfer (trophallaxis). Under laboratory conditions, up to 15% of an ingested PA diet was exchanged from bee to bee, disclosing a possible route for incorporation into the honey comb. In the absence of alternative nectar and pollen sources, PA-containing plants might exhibit a threat to vulnerable bee larvae, and this might affect the overall colony fitness.     

SiGe BiCMOS technology for RF circuit applications

SiGe BiCMOS is reviewed with focus on today's production 0.18-/spl mu/m technology at f/sub T//f/sub MAX/ of 150/200 GHz and future technology where device scaling is bringing about higher f/sub T//f/sub MAX/, as well as lower power consumption, noise figure, and improved large-signal performance at higher levels of integration. High levels of radio frequency (RF) integration are enabled by the availability of a number of active and passive modules described in this paper including high voltage and high-power devices, complementary PNPs, high quality MIM capacitors, and inductors. Key RF circuit results highlighting the advantages of SiGe BiCMOS in addressing today's RF IC market are also discussed both for applications at modest frequencies (1 to 10 GHz) as well as for emerging applications at higher frequencies (20 to >100 GHz).     

Obstructive renal insufficiency caused by amoxicillin crystalluria

A 76-year-old woman was admitted to the ICU for a meningitis with rhombencephalitis due to Listeria monocytogenes. The treatment included amoxicillin (250 mg.kg-1.day-1) and gentamicin (3 mg.kg-1.day-1 over 6 days). Neurological outcome was favourable. However at the 14th day, an acute renal failure occurred, following macroscopic haematuria and milkiness urine. CT scan and sonography confirmed the diagnosis of obstructive renal failure with bilateral ureteral obstruction. Crystalluria caused by amoxicillin was suspected. Endoscopic ureteral insertion of double-J catheters permitted the recovery of a normal renal function.     

Wireless Personal Communications special issue on Security for Next Generation Communications

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