The effects of material formulation and manufacturing process on mechanical and thermal properties of epoxy/clay nanocomposites

A holistic study was conducted to investigate the combined effect of three different pre-mixing processes, namely mechanical mixing, ultrasonication and centrifugation, on mechanical and thermal properties of epoxy/clay nanocomposites reinforced with different platelet-like montmorillonite (MMT) clays (Cloisite Na+, Cloisite 10A, Cloisite 15 or Cloisite 93A) at clay contents of 3–10 wt%. Furthermore, the effect of combined pre-mixing processes and material formulation on clay dispersion and corresponding material properties of resulting composites was investigated using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), flexural and Charpy impact tests, Rockwell hardness tests and differential scanning calorimetry (DSC). A high level of clay agglomeration and partially intercalated/exfoliated clay structures were observed regardless of clay type and content. Epoxy/clay nanocomposites demonstrate an overall noticeable improvement of up to 10 % in the glass transition temperature (Tg) compared to that of neat epoxy, which is interpreted by the inclusion of MMT clays acting as rigid fillers to restrict the chain mobility of epoxy matrices. The impact strength of epoxy/clay nanocomposites was also found to increase by up to 24 % with the addition of 3 wt% Cloisite Na+ clays. However, their flexural strength and hardness diminished when compared to those of neat epoxy, arising from several effects including clay agglomeration, widely distributed microvoids and microcracks as well as weak interfacial bonding between clay particles and epoxy matrices, as confirmed from TEM and SEM results. Overall, it is suggested that an improved technique should be used for the combination of pre-mixing processes in order to achieve the optimal manufacturing condition of uniform clay dispersion and minimal void contents

New AMS 14C dates track the arrival and spread of broomcorn millet cultivation and agricultural change in prehistoric Europe

Broomcorn millet (Panicum miliaceum L.) is not one of the founder crops domesticated in Southwest Asia in the early Holocene, but was domesticated in northeast China by 6000 bc. In Europe, millet was reported in Early Neolithic contexts formed by 6000 bc, but recent radiocarbon dating of a dozen 'early' grains cast doubt on these claims. Archaeobotanical evidence reveals that millet was common in Europe from the 2nd millennium bc, when major societal and economic transformations took place in the Bronze Age. We conducted an extensive programme of AMS-dating of charred broomcorn millet grains from 75 prehistoric sites in Europe. Our Bayesian model reveals that millet cultivation began in Europe at the earliest during the sixteenth century bc, and spread rapidly during the fifteenth/fourteenth centuries bc. Broomcorn millet succeeds in exceptionally wide range of growing conditions and completes its lifecycle in less than three summer months. Offering an additional harvest and thus surplus food/fodder, it likely was a transformative innovation in European prehistoric agriculture previously based mainly on (winter) cropping of wheat and barley. We provide a new, high-resolution chronological framework for this key agricultural development that likely contributed to far-reaching changes in lifestyle in late 2nd millennium bc Europe

Introducing argumentative and discursive enterprise leading and management

Leading an enterprise requires, obviously, decision making. However, these decisions require explanations in order to make it possible for stakeholders to get an understanding about the enterprise's strategic direction. This is even more important when these stakeholders are in charge to transpose such strategic decision into their tactical or operational work. Enterprise modelling may be capable of depicting strategies per se, but it is rather a vessel of communication than of explanation. Whilst, a strategy may be accordingly modelled, those who receive such a model needs to purposeful interpret and successfully implement it. However, without any insights, justifications or references that go beyond the claim of a model, it is dificult to embrace the theory of the actual modeller. Therefore, in this paper argumentative modelling will be specifically applied to the domain of strategic management. Moreover it will be elucidated how modelled strategic arguments can be used as a basis for enterprise architecture alignment and management. As it will be shown in the paper, the application of argumentative modelling overcomes classical restrictions and makes it possible to support a discourse, which can be later on used as an explanation for the intentions of the modeller. Copyright © 2013 for the individual papers by the papers' authors

Demand peaks and cost pass-through: a case of Irans's poultry market

This article examines cost pass-through and pricing behavior for fresh poultry meat during periods of peak demand. The analysis is conducted on weekly poultry wholesale-retail price data collected in all provinces of Iran from 2010 to 2016. Two traditional festivals are identified as periods of peak demand. We use a panel co-integration framework to estimate pass-through elasticity and speed of adjustment during peak and off-peak periods. We find that wholesale and retail prices increase during these periods, while retail margins decline. We interpret these findings as increased retail competition during periods of peak demand. Moreover, our findings confirm a more sluggish price adjustment during these periods. Acknowledgement : This research was supported by Kiel University funding

MIXED GONADAL DYSGENESIS WITH 45,X/46,X,IDIC(Y)/46,XY,IDIC(Y) KARYOTYPE

Mixed gonadal dysgenesis with 45,X/46,X,idic(Y)/46,XY,idic(Y) karyotype: To present the new karyotype with mixed gonadal dysgenesis, the aetiologic approach and difficulties in genetic counseling in mosaic sex chromosome disorders. We report a fourteen-year-old boy presented with slightly ambigious genitalia. Cytogenetic and fluorescence in situ hybridization investigations were carried out on his peripheral lymphocytes. As a result, three cell lines, 45,X, 46,X,idic(Y)(q11.2) and 46, XY were observed. A markedly higher percentage of Y-containing cells was observed in the blood (68%), which was not considered to be the major reason why the case did not have distinct ambiguous genitalia. We suggest that study of cytogenetic and molecular mosaicism involving sex chromosomes may help to further unravel the mysterious process in mixed gonadal dysgeneic patients