Shape memory crosslinked polyurethanes containing thermoreversible Diels‐Alder couplings

Crosslinked polyurethanes (PUs) containing irreversible (allophanate) and reversible Diels‐Alder chemical bonds were synthesized using various diisocyanates (methylene diphenyl diisocyanate MDI, 1,6‐hexamethylenediisocyanate HDI) and poly(?‐caprolactone) ((PCL) with different molecular weights (M_n = 10 kg/mol, 25 kg/mol, 50 kg/mol) as diol component. The melting/crystallization of PCL and the reversible DA bonds acted as temperature‐activated switches for shape memory performances, while allophanate network provided the permanent crosslinks for these PUs. The reversible DA bonds were obtained by the reaction of diisocyanate‐ended prepolymers with furfurylamine (FA) followed by the addition of bismaleimide (BMI). The permanent crosslinks between the linear chains containing DA bonds were achieved using additional amounts of diisocyanates (MDI or HDI). The above reaction path was supported by infrared spectroscopic results and swelling experiments. Tensile mechanical and shape memory properties in tension of the PUs were determined and discussed as a function of composition and crosslink densities deduced from swelling and dynamic mechanical analysis. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44145.     

Detection of ammonia by photoacoustic spectroscopy with semiconductor lasers

Sensitive photoacoustic detection of ammonia with near-infrared diode lasers (1.53 microns) and a novel differential acoustic resonator is described; a sensitivity of 0.2 parts per million volume (signal-to-noise ratio = 1) is attained. To eliminate adsorption-desorption processes of the polar NH3 molecules, a relatively high gas flow of 300 SCCM was used for the ammonia-nitrogen mixture. The results are compared with recent ammonia measurements with a NIR diode and absorption spectroscopy used for detection and photoacoustic experiments performed with an infrared quantum-cascade laser. The performance of the much simpler and more compact setup introduced here was comparable with these previous state-of-the-art measurements.     

(R)-acetoin-female sex pheromone of the summer chafer Amphimallon solstitiale (L.)

Extracts of Amphimallon solstitiale (L.), a well known, widely distributed and rather common European scarab beetle, were analyzed by GC-MS and GC-EAD. Acetoin -(R):(S) < 9:1 - as well as 2,3-butanediol -(2R,3R):(2S,3S) :meso = 1:1:9 - were present in extracts of both males and females. Although (2S,3S)-butanediol did not show any EAD activity, the other compounds elicited strong responses exclusively with male antennae. In contrast, several EAD active green leaf volatiles were detected equally well by male and female antennae. During preliminary field bioassays, (R)-acetoin was highly attractive to swarming males, whereas neither rac-acetoin nor the 2,3-butanediols showed activity. Therefore, (R)-acetoin is the female sex pheromone of A. solstitiale.     

Scalable Schemes for Call Admission and Handover in Cellular Networks with Multiple Services

The introduction of new service categories withdifferent bandwidth requirements, e.g., data and multimedia, to cellularmobile radio networks makes many of the traditional mechanisms for controlingtraffic unusable orless efficient. The call admission and the handover handling are of the mostsensitive issues in this extension to new services. The performance of allservices includingthe traditional voice and the new services can be dramatically affected ifappropriate schemes are not used. In this paper, we propose call admission andhandover handling schemes for a cellular mobile network that offers twoservice types: voice and data. The data connections are assumed to transmitatdifferent transmission rates that are integer multiples to that of one radiochannel. In the case of congestion, the base station asks the active dataconnections to reduce their transmission rate in order to provide freechannels for the newly arrived request of both service types. This isbasically intended for incoming handover requests. The request will berejected if the transmission rate of the active connections reaches a givenminimum rate. Similar mechanism can also be used for new call arrivals, butsome priority can be given to handovers by setting a higher transmission ratethreshold for the new call rejection. As an extension to the proposedscalability, aqueuing of new calls is also proposed and analyzed. Analytical models werebuilt for the two proposed schemes together with the traditional channelreservation scheme. The effect of different traffic and configurationparameters on the performance measures like the grade of service, blockingprobabilities, and utilization, are studied using the proposed technique.Results show that the proposed schemes provide very good performance and morefairness among the different service types.     

Dogs' ( Canis familaris ) responsiveness to human pointing gestures.

In a series of 3 experiments, dogs (Canisfamiliaris) were presented with variations of the human pointing gesture; gestures with reversed direction of movement, cross-pointing, and different arm extensions. Dogs performed at above chance level if they could see the hand (and index finger) protruding from the human body contour. If these minimum requirements were not accessible, dogs still could rely on the body position of the signaler. The direction of movement of the pointing arm did not influence the performance. In summary, these observations suggest that dogs are able to rely on relatively novel gestural forms of the human communicative pointing gesture and that they are able to comprehend to some extent the referential nature of human pointing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An adsorptive transfer technique coupled with brdicka reaction to reveal the importance of metallothionein in chemotherapy with platinum based cytostatics

The drugs based on platinum metals represent one of the oldest, but also one of the most effective groups of chemotherapeutic agents. Thanks to many clinical studies it is known that resistance of tumor cells to drugs is a frequent cause of chemotherapy failure. With regard to platinum based drugs, multidrug resistance can also be connected with increased expression of low-molecular weight protein metallothionein (MT). This study aimed at investigating the interactions of MT with cisplatin or carboplatin, using the adsorptive transfer technique coupled with differential pulse voltammetry Brdicka reaction (AdTS DPV Brdicka reaction), and a comparison of in vitro results with results obtained in vivo. The results obtained from the in vitro study show a strong affinity between platinum based drugs and MT. Further, we analyzed extracts of neuroblastoma cell lines treated with cisplatin or carboplatin. It is clear that neuroblastoma UKF-NB-4 cisplatin-resistant and cisplatin-sensitive cell lines unlikely respond to the presence of the platinum-based cytostatics cisplatin and carboplatin. Finally, we determined the level of MT in samples from rabbits treated with carboplatin and patients with retinoblastoma treated with the same drug.