Volunteer Trustees in Urban United Way Agencies

The purpose of this study was to examine the perceptions of role and function of trustees and chief professional officers (CPOs) in non-profit, human services agencies that are members of the United Way of South Hampton Roads. Thousands of volunteer hours are expended annually in serving on boards of directors in the Hampton Roads area. These trustees who serve are legally accountable for the agencies, and have certain duties prescribed by their by-laws. However, role confusion and conflict exist over specific duties of trustees. Responsibilities of for-profit board members were divided into four areas: management--control and oversight; adherence to legal prescriptions; consideration of stakeholders\u27 interests; and consideration of stockholders\u27 interests. Within these four areas were grouped trustees\u27 responsibilities as found within the body of literature on non-profit agency administration. A survey, in questionnaire form, based on the literature and discussion with United Way managerial staff, was developed and administered to trustees and CPOs (N = 130) of the 13 agencies designated for study. Stepwise discriminant analysis was used to determine those variables which would most discriminate between least effective and most effective trustees. The analyses produced three functions that correctly classified 67 percent of trustees (N = 117): Organizational Awareness, Shared Managerial Responsibilities, and Trustee Administrative Duties. The null hypotheses, that there were no significant differences between most effective and least effective trustees, were not supported

Crystal structures and polymorphism of polymers: Influence of defects and disorder

The crystal structures and the polymorphism of polymers are described on the basis of the main principles that define the conformation of polymer chains in the crystalline state and the modes of packing of macromolecules. We show that the presence of defects and disorder in the crystals influences the polymorphic behavior. The cases of polymorphism of isotactic poly(butene) (iPB) and syndiotactic poly(styrene) (sPS) are ilustrated as examples. In the case of iPB, the effect of the presence of defects of stereoregularity and of comonomeric units on the crystallization of form I and form II is described as an example of alteration of the crystallization behavior because of the modification of both thermodynamic stability and crystallization kinetics from the melt of the polymorphic forms. The case of sPS is taken as an example of a very complex polymorphic behavior arising from the presence and development of structural disorder

Novel polyolefin based elastomers with tailored stiffness from metallorganic catalysis: the crystalline elastomers.

This project is aimed at studying the new class of materials defined "crystalline elastomers", which are innovative polyolefin-based elastomers that present increased and tailored stiffness, with respect to conventional elastomers, thanks to the presence of non-negligible level of crystallinity. These materials are characterized by a combination of mechanical properties typical of crystalline polymers (high mechanical strength and stiffness) and of elastomers (ease of deformability, ductility and perfect elasticity)

Propylene–Butene Copolymers: Tailoring Mechanical Properties from Isotactic Polypropylene to Polybutene

Isotactic propylene-butene copolymers [i(P-co-B)] with precise and controlled molecular structures were synthesized with various organometallic catalysts having different stereoselectivities. Stereoregular and stereodefective samples of i(P-co-B) with 1-butene (B) content variable in the whole range of composition were synthesized. All samples crystallize regardless of composition, indicating cocrystallization of propene and 1-butene units, which are incorporated in the unit cells of polymorphic forms of isotactic poly(propylene) (iPP) and isotactic poly(1-butene) (iPB). The copolymers show a continuum change of crystal morphology with the composition, transforming from big spherulites to bundle-like and needle-like crystals, to granular crystals. The cocrystallization allows maintaining high crystallinity of copolymers for any composition and provides an opportunity to develop outstanding mechanical properties that can be tailored by changing the isotacticity and composition. This allows, ideally, combining in the same material the different properties of stiffness of iPP and flexibility of iPB. These copolymers show, indeed, mechanical properties intermediate between iPP and iPB, ranging from stiffness/brittleness and ductility/flexibility depending on the composition and isotacticity, with high strength and Young's modulus that may be regulated by the stereoregularity of the iPP and iPB sequences, which is, in turn, dictated by the catalyst structure

Melt-Crystallizations of α and γ Forms of Isotactic Polypropylene in Propene-Butene Copolymers

Random isotactic propene-butene copolymers (iPPC4) of different stereoregularity have been synthesized with three different homogeneous single center metallocene catalysts having different stereoselectivity. All samples crystallize from the polymerization solution in mixtures of α and γ forms, and the relative amount of γ form increases with increasing concentrations of butene and of rr stereodefects. All samples crystallize from the melt in mixtures of α and γ forms and the fraction of γ form increases with decreasing cooling rate. At high cooling rates, the crystallization of the α form is always favored, even for samples that contain high total concentration of defects that should crystallize in the γ form. The results demonstrate that in iPPs containing significant concentrations of defects, such as stereodefects and comonomeric units, the γ form is the thermodynamically stable form of iPP and crystallizes in selective conditions of very slow crystallization, whereas the α form is the kinetically favored form and crystallizes in conditions of fast crystallization

Isotactic and syndiotactic alternating ethylene/propylene copolymers obtained through non-catalytic hydrogenation of highly stereoregular cis-1,4 poly(1,3-diene)s

The homogeneous non-catalytic hydrogenation of cis-1,4 poly(isoprene), isotactic cis-1,4 poly(1,3-pentadiene) and syndiotactic cis-1,4 poly(1,3-pentadiene) with diimide, formed by thermal decomposition of para-toluenesulfonylhydrazide, is examined. Perfectly alternating ethylene/propylene copolymers having different tacticity (i.e., isotactic and syndiotactic), which are difficult to synthesize by stereospecific copolymerization of the corresponding monomers, are obtained. Both isotactic and syndiotactic alternating ethylene/propylene copolymers are amorphous, with very low glass transition temperatures

Morphology of Isotactic Polypropylene–Polyethylene Block Copolymers Driven by Controlled Crystallization

A study of the morphology of diblock copolymers composed of two crystalline blocks of isotactic polypropylene (iPP) and polyethylene (PE) is shown. The samples form phase-separated structures in the melt because of the incompatibility between iPP and PE blocks. Cylindrical PE microdomains are visible at room temperature in the sample with a PE volume fraction of 26%, rapidly quenched from the melt in liquid nitrogen. In the quenched sample, PE crystallizes inside the PE cylindrical microdomains, whereas crystals of iPP are not visible in the iPP domains because the quenching prevents crystallization of the lamellar α form. Less rapid cooling of the melt produces, instead, breakout crystallization, where the phase-separated structure of the melt is destroyed by the slow crystallization of the α form of iPP and of PE. The succession of crystallization of iPP and PE and the resulting final morphology have been analyzed by inducing selective and different orientations of iPP and PE crystals through epitaxial crystallization onto the benzoic acid (BA) crystal substrate. Epitaxy produces oriented crystallization of iPP and PE, with a unique alignment of PE lamellar crystals and a double orientation of iPP crystals on to the (001) exposed face of BA. Epitaxy destroys the phase-separated structure of the melt and induces the formation of ordered lamellar nanostructures with alternated layers of iPP and PE, whose orientation is defined by the alignment of PE or iPP crystals, which, in turn, is determined by epitaxy. The results indicate that crystalline block copolymers offer the opportunity to create nanoscale patterns on thin films and improve the possibility of controlling the microstructure of block copolymers and the alignment of microdomains by controlling the crystallization process

Time-resolving small angle X-Ray scattering analysis of melt crystallization of mixtures of regular and irregular isotactic polypropylene samples

The melting/crystallization properties of blends obtained by mixing two isotactic polypropylene (iPP) samples synthesized using single-site metallocene catalyst systems and containing a high and low concentration of rr triads as stereo-defects, are studied. The changes occurring at lamellar length scale during a heating/cooling cycle at constant scanning rate are followed in situ by performing time-resolved small angle X-ray scattering (SAXS) measurements. Data analysis demonstrates that the evolution of the SAXS intensity with increase/decrease of the temperature is controlled by the separate melting/crystallization of the two components, the differences in the thermal expansion (contraction) coefficient of the amorphous and crystalline phases and the role of thermal fluctuations in electron density. The two components give rise to different populations of intermixed lamellar stacks in the blends which originate from the good miscibility of the low and high stereoregular samples in the melt.info:eu-repo/semantics/publishedVersio

Pharmacological activation of autophagy favors the clearing of intracellular aggregates of misfolded prion protein peptide to prevent neuronal death

According to the "gain-of-toxicity mechanism", neuronal loss during cerebral proteinopathies is caused by accumulation of aggregation-prone conformers of misfolded cellular proteins, although it is still debated which aggregation state actually corresponds to the neurotoxic entity. Autophagy, originally described as a variant of programmed cell death, is now emerging as a crucial mechanism for cell survival in response to a variety of cell stressors, including nutrient deprivation, damage of cytoplasmic organelles, or accumulation of misfolded proteins. Impairment of autophagic flux in neurons often associates with neurodegeneration during cerebral amyloidosis, suggesting a role in clearing neurons from aggregation-prone misfolded proteins. Thus, autophagy may represent a target for innovative therapies. In this work, we show that alterations of autophagy progression occur in neurons following in vitro exposure to the amyloidogenic and neurotoxic prion protein-derived peptide PrP90-231. We report that the increase of autophagic flux represents a strategy adopted by neurons to survive the intracellular accumulation of misfolded PrP90-231. In particular, PrP90-231 internalization in A1 murine mesencephalic neurons occurs in acidic structures, showing electron microscopy hallmarks of autophagosomes and autophagolysosomes. However, these structures do not undergo resolution and accumulate in cytosol, suggesting that, in the presence of PrP90-231, autophagy is activated but its progression is impaired; the inability to clear PrP90-231 via autophagy induces cytotoxicity, causing impairment of lysosomal integrity and cytosolic diffusion of hydrolytic enzymes. Conversely, the induction of autophagy by pharmacological  blockade of mTOR kinase or trophic factor deprivation restored autophagy resolution, reducing intracellular PrP90-231 accumulation and neuronal death. Taken together, these data indicate that PrP90-231 internalization induces an autophagic defensive response in A1 neurons, although incomplete and insufficient to grant survival; the pharmacological enhancement of this process exerts neuroprotection favoring the clearing of the internalized peptide and could represents a promising neuroprotective tool for neurodegenerative proteinopathies