Does collaboration pay in agricultural supply chain? An empirical approach

This paper examines the effect of different types of collaboration on the level of Postharvest Food Losses (PHFL) and the proportion of low-quality peaches produced using a unique data-set of Greek peach producers. Quantile regression techniques are adopted to estimate the effects at different points of the conditional distribution of our variables of interest. The findings of this study suggest that high levels of collaboration between producers and cooperatives are associated with both low levels of PHFL and a low proportion of low-quality peaches. We also find that specific types of collaboration, such as ‘goal congruence’, can play a significant role in reducing PHFL and improving the quality of peach production at the extremes of the distribution. Important policy implications regarding collaborative practices and systems that can be implemented to reduce PHFL and boost a producer’s performance together with sustainability credentials are drawn from this study

Producers Responding to Environmental Turbulence in the Greek Agricultural Supply Chain:Does Buyer Type Matter?

There are many changes in the EU Agricultural Supply Chain (ASC). These changes cause environmental turbulence for supply chain entities operating in this sector. In the Greek ASC, there is a significant decline in its performance in particular at producers’ level. Based on the Contingency Theory this paper aims to identify the relevant environmental turbulence factors in Greek ASC context from the producers’ perspective and ascertain their impact on producers based on their choice of buyer type i.e. collaboration type. Twenty in-depth semi-structured interviews were conducted with Greek ASC producers. Thematic analysis was used to analyse the interviews. The findings suggest the existence of six major environmental turbulence factors at producers’ level which are: regulatory, market, competitive, weather, economic and political turbulence factors. Producers selling their products to cooperatives were found to be significantly impacted by the different environmental turbulence factors. Future research directions as well as managerial and policy implications are identified

DPPC/poly(2-methyl-2-oxazoline)-grad-poly(2-phenyl-2-oxazoline) chimeric nanostructures as potential drug nanocarriers

In this study, we report on the self assembly behavior and on stability studies of mixed (chimeric) nanosystems consisting of dipalmitoylphosphatidylcholine (DPPC) and poly(2-methyl-2-oxazoline)-grad- poly(2-phenyl-2-oxazoline) (MPOx) gradient copolymer in aqueous media and in fetal bovine serum (FBS). A gamut of light scattering techniques and fluorescence spectroscopy were used in order to extract information on the size and morphological characteristics of the nanoassemblies formed, as a function of gradient block copolymer content, as well as temperature. The hydrodynamic radii (R h) of nanoassemblies decreased in the process of heating up to 50 C, while the fractal dimension (d f) values, also increased. Indomethacin was successfully incorporated into these chimeric nanocarriers. Drug release was depended on the components ratio. The present studies show that there are a number of parameters that can be used in order to alter the properties of chimeric nanosystems, and this is advantageous to the development of "smart" nanocarriers for drug delivery. © 2013 Springer Science+Business Media Dordrecht

Amphiphilic gradient copolymers of 2-methyl- and 2-phenyl-2-oxazoline: Self-organization in aqueous media and drug encapsulation

Gradient (or pseudo-diblock) copolymers were synthesized from 2-methyl-2-oxazoline and 2-phenyl-2-oxazoline monomer mixtures via cationic polymerization. The self-assembling properties of these biocompatible gradient copolymers in aqueous solutions were investigated, in an effort to use the produced nanostructures as nanocarriers for hydrophobic pharmaceutical molecules. Dynamic and static light scattering as well as AFM measurements showed that the copolymers assemble in different supramolecular nanostructures (spherical micelles, vesicles and aggregates) depending on copolymer composition. Fluorescence spectroscopy studies revealed a microenvironment of unusually high polarity inside the nanostructures. This observation is related partly to the gradient structure of the copolymers. The polymeric nanostructures were stable with time. Their structural properties in different aqueous media-PBS buffer, RPMI solution-simulating conditions used in pharmacological/medicinal studies, have been also investigated and a composition dependent behavior was observed. Finally, the hydrophobic drug indomethacin was successfully encapsulated within the gradient copolymer nanostructures and the properties of the mixed aggregates were studied in respect to the initial copolymer assemblies. The produced aggregates encapsulating indomethacin showed a significant increase of their mass and size compared to original purely polymeric ones. © 2011 Wiley Periodicals, Inc

PEO-b-PCL-DPPC chimeric nanocarriers: Self-assembly aspects in aqueous and biological media and drug incorporation

In this work, we report on the self assembly behavior and stability studies of mixed amphiphilic nanosystems consisting of DPPC (dipalmitoylphosphatidylcholine) and poly(ethylene oxide)-b-poly(ε- caprolactone) (PEO-b-PCL) block copolymer in HPLC-grade water, phosphate buffer saline (PBS) and fetal bovine serum (FBS). These nanosystems are sterically stabilized nanovectors and can be utilized as chimeric advanced Drug Delivery nano Systems (aDDnSs) with stealth properties. A gamut of light scattering techniques (static, dynamic and electrophoretic) and fluorescence spectroscopy were used in order to extract information on the structure, morphology, size, effective charge and internal nanostructure of the nanoassemblies formed, as a function of block copolymer content, as well as temperature and concentration. The incorporation of PEO-b-PCL leads to nanoassemblies of smaller size. All the mixed formulations were found to retain their original physicochemical characteristics for the course of two weeks. The hydrodynamic radii (R h) of mixed nanosystems decreased in the process of heating up to 50 °C. Gradual degradation of the polymeric chain in an acidic dispersion medium, which leads to gradual structural changes of the chimeric nanovectors, was observed. The micropolarity of the hydrocarbon region of nanocarriers changed significantly in HPLC-grade water and PBS with increasing block copolymer content. The incorporation of indomethacin (IND) led to a decreased size of chimeric nanocarriers. The incorporation efficiency of mixed liposomal-block copolymer formulations for IND was increased in PBS in comparison with the HPLC-grade water, due to electrostatic interactions between the drug molecule and choline headgroups. PEO-b-PCL grafted DPPC liposomes are found to be effective nanocontainers for the encapsulation of IND, especially at the highest molar ratio of the block copolymer. © The Royal Society of Chemistry 2013

Block copolymers for Drug Delivery nano Systems (DDnSs)

The application of polymers in medicine, as components of drug carriers, as well as their synthetic strategies are considered essential for producing and developing new drug formulations against human deceases. The synthesis of block copolymers is a timeconsuming process with a high cost of the final product, although several block copolymer systems have been already commercialized successfully. The biocompatibility, the biodegradability and the non toxic profile of newly synthesized polymers towards healthy tissues, should be taken into account in order to be acceptable for biomedical applications. In this review article, focus is placed on new approaches and synthetic strategies for preparing novel block copolymers and their utilization as parts of new and advanced Drug Delivery nanoSystems (aDDnSs) with a Modulatory Controlled Release profile (MCR). Such complex and advanced nanosystems can alter the pharmacokinetic properties of the encapsulated drug and consequently its effectiveness. Emphasis is given to the use of living polymerization methodologies and post polymerization chemical transformation reactions for the synthesis of mainly diblock copolymers for novel drug delivery nanosystems. Issues related to self-assembly of block copolymers in solution toward formation of colloidal functional nanostructures that can serve as nanocontainers and nanocarriers, and strategies for controlling encapsulation of specific drugs are also discussed. Specific examples are reported mainly on diblock copolymer systems, including authors' recent work. © 2012 Bentham Science Publishers

β-lactam functionalized poly(isoprene-b-ethylene oxide) amphiphilic block copolymer micelles as a new nanocarrier system for curcumin

Curcumin is a natural compound with biological activities and potent anticancer effects that has the drawback of poor water solubility which leads to low bioavailability. In this work curcumin was formulated in new physicochemically characterized micellar carriers composed of new synthetic block copolymers. The study of the in vitro release rate of curcumin from the formulas, as well as the in vitro activity of free curcumin and of curcumin-loaded into micelles, against a panel of colorectal cancer cell lines was also part of this study. New β -lactam functionalized poly(isoprene-b-ethylene oxide) amphiphilic block copolymers, were synthesized by the combination of anionic polymerization and selective postpolymerization functionalization of the polyisoprene block with chlorosulfonylisocyanate. Micelles composed of the synthetic copolymers were formulated in order to incorporate curcumin. As the results revealed, increase in the percentage of the lipophilic block of micelles, led to higher encapsulation efficiency and loading capacity while the size was found to be smaller and the in vitro release rate slower. In vitro cytotoxicity results showed similar or slightly higher activity for curcuminloaded into micelles than free curcumin, a fact that could be attributed to the similar in vitro cellular uptake profiles of curcumin and of curcumin-loaded into micelles. © 2010 Bentham Science Publishers Ltd

Price Transmission and Market Power in Modern Agricultural Value Chains

"Modern" agricultural markets are characterized by, among other things, quality requirements and vertical coordination. The nature of the industrial organization of the value chain depends on a variety of factors, such as local institutions, economic growth, demand, institutional infrastructure etc. In this paper we present a conceptual framework to explicitly integrate key characteristics of these "modern" agricultural markets and derive implications for price transmission and market power in these markets and value chains