Alkyl-functionalized oxide-free silicon nanoparticles: synthesis and optical properties

Highly monodisperse silicon nanoparticles (1.57 +/- 0.21 nm) are synthesized with a covalently attached alkyl monolayer on a gram scale. Infrared spectroscopy shows that these silicon nanoparticles contain only a few oxygen atoms per nanoparticle. XPS spectra clearly show the presence of unoxidized Si and attached alkyl chains. Owing to the relatively efficient synthesis (yields approximately 100-fold higher than of those previously reported) the molar extinction coefficient epsilon can be measured: epsilon(max) = 1.7 x 10(-4) M(-1)cm(-1), only a factor of 4 lower than that of CdS and CdSe nanoparticles of that size. The quantum yield of emission ranges from 0.12 (C(10)H(21)-capping) to 0.23 (C(16)H(33)-capping). UV/Vis absorption and emission spectroscopy show clear vibrational progressions (974 +/- 14 cm(-1); up to five vibrational bands visible at room temperature), resembling bulk SiC phonons, which support the monodispersity observed by TEM. This was also confirmed by time-resolved fluorescence anisotropy measurements, which display a strictly monoexponential decay that can only be indicative of monodisperse, ball-shaped nanoparticles.     

Olfactory Cue Mediated Neonatal Recognition in Sheep, Ovis aries

The strong bond between ewe and lamb formed shortly after parturition is an important factor in lamb survival. Evidence exists that a ewe can distinguish her lamb by its unique smell, but the constituents of such a putative olfactory cue have not yet been identified. We have now identified 133 volatile organic compounds associated with the wool of Döhne Merino lambs that we presume may be involved in neonatal recognition. Quantitative analysis and comparison of odor profiles of the twins of 16 ewes (9.69% sample group) of a flock of 165 twin-bearing ewes revealed that the wool volatiles of twins are qualitatively and quantitatively similar, but differ from those of other twins or non-twin lambs in the flock. The 88 constituents present in at least 20% of the analyzed wool samples were considered as variables for multivariate analysis. A P-value?相似文献   

Zusammensetzung von Klebreis

Zusammenfassung 15 Muster Ketan wurden auf ihre Zusammensetzung untersucht. Der Gehalt an wirklicher Stärke war nur wenige Prozent geringer als der Gehalt an sog. Gesamt-Stärke. Der Unterschied muß der Anwesenheit von Dextrin oder von anderen Stärkeabbauprodukten zugeschrieben werden, jedoch nicht der von Zucker.Schwarzer Ketan hat einen höheren Gehalt an Eiweiß, Fett und Asche als weißer Ketan und verdient darum den Vorzug als Nahrungsmittel.Es besteht eine mathematisch zufriedenstellende Korrelation zwischen dem Gehalt an B₁-Vitamin und Phosphorsäure im Ketan, wobei im Mittel 100 B₁-Vitamin-Einheiten 0,146% P₂O₅ entsprechen.     

The temporal dynamics of the stress response

This paper summarises the available evidence that failure of defense mechanisms in (semi)-natural social groups of animals may lead to serious forms of stress pathology. Hence the study of social stress may provide animal models with a high face validity. However, most of the animal models of human stress-disorders have concentrated on the consequences of chronic exposure to stressors. The present paper considers recent data, indicating that a single experience with a major stressor in the form of social defeat may have long-term consequences ranging from hours to days and weeks. It seems that the experience of a major stressor sensitizes the animal to subsequent stressors. The consequences of these long-term temporal dynamics of the stress response to the development of stress-related disorders and stress-vulnerability are discussed.     

The Control of Feather Pecking by Serotonin.

Feather-pecking behavior in laying hens (Callus gallus) may be considered a behavioral pathology, comparable to human psychopathological disorders. Scientific knowledge on the causalion of such disorders strongly suggests involvement of the serotonergic (5-hydroxytryptamine; 5-HT) system in feather pecking. Previously, chicks from a high-feather-pecking (HFP) line were found to display lower 5-HT turnover levels than chicks from a low-feather-pecking (LFP) line (in response to acute stress; Y. M. van Hierden et al., 2002). The present study investigated whether low 5-HT neurotransmission modulates feather pecking. First. S-15535, a somatodendritic 5-HT1A autoreceptor agonist, was demonstrated to be an excellent tool for reducing 5-HT turnover in the forebrain of LFP and HFP chicks. Second, the most effective dose of S-15535 (4.0 mg/kg body weight) significantly increased severe feather-pecking behavior. The results confirmed the postulation that the performance of feather pecking is triggered by low 5-HT neurotransmission. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Model free control based on GIMC structure

Many control researches for complicated and uncertain system are model-dependent and therefore require some prior knowledge for the complex systems. To avoid this problem, a number of model-free controllers are proposed. However, it is difficult to determine the control performance as the controller is not designed according certain system model especially when there are uncertainties and/or nonlinear dynamics in the system. To get over this problem, the model free controller (MFC) based on generalized internal model control (GIMC) structure is proposed in this paper. The MFC is used to attenuate the disturbance or uncertainty, and the system performance is determined by the nominal model and the nominal model controller. The parameters of nominal-model controller can be easily changed for meeting the change of the desired requirements. Moreover, the robust controller in the original GIMC is disassembled and rearranged to make the proposed methods easier to use, and the proposed method makes the controller be more flexible and greatly improves the system performance. Finally, the experiment results show that the MFC can be used to control the nonlinear systems and get the expected performance. The statistical analysis of performance for servo and regulatory behaviors also shows that the proposed method can achieve a better control performance than just using model free controller.     

Sleep and need for recovery in shift workers: do chronotype and age matter?

This study examined associations of chronotype and age with shift-specific assessments of main sleep duration, sleep quality and need for recovery in a cross-sectional study among N = 261 industrial shift workers (96.6% male). Logistic regression analyses were used, adjusted for gender, lifestyle, health, nap behaviour, season of assessment and shift schedule. Shift workers with latest versus earliest chronotype reported a shorter sleep duration (OR 11.68, 95% CI 3.31–41.17) and more awakenings complaints (OR 4.84, 95% CI 4.45–11.92) during morning shift periods. No associations were found between chronotype, sleep and need for recovery during evening and night shift periods. For age, no associations were found with any of the shift-specific outcome measures. The results stress the importance of including the concept of chronotype in shift work research and scheduling beyond the concept of age. Longitudinal research using shift-specific assessments of sleep and need for recovery are needed to confirm these results.

Practitioner Summary: Chronotype seems to better explain individual differences in sleep than age. In view of ageing societies, it might therefore be worthwhile to further examine the application of chronotype for individualised shift work schedules to facilitate healthy and sustainable employment.     

The uncatalysed hydrogenation of coal

The uncatalysed hydrogenation of a bituminous coal in a batch reactor with tetralin as solvent has been investigated. This investigation differs from others on this subject reported in the literature mainly in the sampling methods employed. Because of the methods previously employed, effects of heating to reaction temperature and cooling to ambient conditions were not excluded; this complicated an investigation into the kinetics of coal hydrogenation. In the present investigation samples were withdrawn from the reactor after reaction temperature and pressure had been reached. It is concluded that simple series or parallel reactions suggested in the literature for the hydrogenation of coal are oversimplified mechanisms.     

Rheological approach to the capillary penetration of coating into wood

The penetration of water- and solventborne binders into the capillaries of wood was studied as a function of the viscosity, surface tension, and capillary pressure according to the Washburn equation. During the penetration, water is selectively removed from the coating, which causes a strong increase in viscosity that limits the penetration. Waterborne dispersions and emulsions showed a rapid increase in viscosity with increasing solid matter content. Surface tension of the binder and the adsorption of surfactants to the wood have an additional influence on the maximum penetration. P.O. Box 497, NL-6700 AL Wageningen, The Netherlands