729 research outputs found
Poteri del datore di lavoro e obblighi del lavoratore - Capitolo V
No full textEmployer’s powers and employee’s obligations
The essay carries out a thorough review of the state of art of the balancing between employer’s powers an employee’s obligations, taking into account the role of the Law (particularly, the Italian Civil Code) and the room for the employees’ fundamental rights grant by the Italian Constitution (as well as by the Act enforcing it) to workers.
Moving from the analysis of the disputed grounds of the disciplinary employer’s power toward dependent workers, the Author looks at the core powers of the entrepreneur as an employer (directive, control, disciplinary powers), on one side, and at the specific employees’ obligations (obedience, diligence, faithfulness) on the other one. On the background, lies the principle of equality, implemented through the antidiscrimination law, as a general limit for the exertion of employer’s powers
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Who is Who in Polymer Science: D
No full textDaly, William H. DeSimone, Joseph M
Elements, 2001
No full textThis is the alumni magazine of the Department of Chemistry at Virginia Tech. Inside: Joseph M. DeSimone proves that green chemistry can provide a clean environment
College of Science alumnus receives highest North Carolina civilian honor
No full textVirginia Tech alumnus Joseph M. DeSimone, of Chapel Hill, N.C., has received the 2009 North Carolina Award, the state's highest civilian honor
In vitro and in vivo studies of nanomolded PRINT® particles of precisely controlled size, shape, and surface chemistry
No full textA novel method for the fabrication of polymeric particles on the order of tens of nanometers to several microns is described. This imprint lithographic technique called PRINT (Particle Replication In Non-wetting Templates), takes advantage of the unique properties of elastomeric molds comprised of a low surface energy perfluoropolyether network, allowing the production of monodisperse, shape-specific nanoparticles from an extensive array of organic precursors. This engineered nature of particle production has a number of advantages over the construction of traditional nanoparticles such as liposomes, dendrimers, and colloidal precipitates. The gentle top down approach of PRINT enables the simultaneous and independent control over particle size and shape, composition, and surface functionality, and permits the loading of delicate cargos such as small organic therapeutics and biological macromolecules. Thus, this single tool serves as a comprehensive platform for the rational design and investigation of new nanocarriers in medicine, having applications ranging from therapeutics to advanced diagnostics. Preliminary in vitro and in vivo studies were conducted, demonstrating the future utility of PRINT particles as delivery vectors in nanomedicine. The interaction of particles with cells is known to be strongly influenced by particle size, however little is known about the interdependent role that size, shape and surface chemistry have on cellular internalization and intracellular trafficking. The internalization of specially-designed, monodisperse hydrogel particles was examined using HeLa cells as a function of size, shape, and surface charge. Evidence of particle internalization was obtained using conventional biological techniques as well as transmission electron microscopy. These findings suggest that HeLa cells readily internalize non-spherical particles with dimensions as large as 3 m using several different mechanisms of endocytosis. Moreover, it was found that rod-like particles enjoy an appreciable advantage when it comes to internalization rates, reminiscent of the advantage that many rod-like bacteria have for internalization in non-phagocytic cells
University of Rochester Department of Chemistry Annual Newsletter 07/01/10 - 06/30/11
No full text2010-2011 Newsletter includes Chair's Message: Robert K. Boeckman, Jr., Alumni News, Esther M. Conwell receives National Medal Science, Richard Eisenberg Symposium, Death of Jack Kampmeier, Magomedov-Shcherbinina Award: Xiowei Zhuang, Harrison Howe Award: Joseph DeSimone, Michael Neidig arrives, New Organic Lab, Faculty News & Publications, Commencement 2011, Staff New
Designing Chemistry for the Environment: From Processing Fluoropolymers Solutions in Supercritical Carbon Dioxide to New Nonbiopersistent Fluorinated Coating Materials
No full textThe solution properties of a fluorinated alkyl methacrylate, poly(1,1,2,2-tetrahydro perfluorooctyl methacrylate) (PFOMA) in carbon dioxide (CO2) were studied by static and dynamic light scattering. The solvent quality of CO2 was found to improve with increasing temperature and CO2 density as exhibited by an increase of the second virial coefficient. Both the hydrodynamic radius expansion factor and the second virial coefficient of PFOMA solution were found to be functions of a single interaction parameter that can be independently changed by either temperature or density variations. Furthermore, we demonstrate that the relationship between two directly measurable quantities, the second virial coefficient and the hydrodynamic expansion ratio, is the same for both temperature-induced and CO2 density-induced variations of solvent quality. The degradation of coating materials that contain long perfluoro chains leads to the release of biopersistent perfluorooctanoic acid (PFOA) into the environment. In order to find environmentally friendly substitutes, a series of fluorinated alkyl methacrylate polymers containing the shorter and non-biopersistant perfluorobutyl group as the fluorinated component of the side chains are synthesized starting from perfuorobutyl iodide. Thermal properties of the polymers were characterized by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Static and dynamic contact angle measurements were used to quantify the surface properties of the thin films for these new non-biopersistant materials (C4 materials). The surface construction, especial the orientation of the fluorinated side chains, were recorded by near edge X-ray fine absorption structure (NEXAFS) experiments. In all, C4 materials displayed the hydrophobic and oleophobic properties with low surfaces tensions and their wetting properties were tuned by varying the "spacer" structures between the backbones and the perfluorinated groups of the side chains
Targeted PRINT® nanoparticles for effective cancer therapy
No full textConventional therapeutics for the treatment of cancer are often faced with challenges such as systemic biodistribution within the body, drug degradation in vivo, low bioavailability at the site of disease, and off-target toxicity. As such, particulate drug delivery systems have been developed with the aim of minimizing these limitations of current therapies. Through the PRINT® (Particle Replication in Non-wetting Templates) technology, hydrogel nanoparticles, prepared from biocompatible poly(ethylene glycol) and acid-sensitive silyl ether crosslinkers, were functionalized and conjugated with targeting ligands for the folate receptor (FR), HER2 receptor, and transferrin receptor (TfR). By conjugating specific ligands to nanoparticles to impart specificity, highly selective targeting and internalization (>80%) of nanoparticles were demonstrated in various cancer cell lines. The extent of cellular uptake of targeted nanoparticles was dependent on the surface characteristics of the nanoparticles, particle concentration, and kinetics. Because a negative surface charge reduces nonspecific cellular uptake, attaching monoclonal antibodies to the surface of negatively charged PRINT nanoparticles facilitated specific binding of the antibodies to cellular surface receptors that subsequently triggered receptor-mediated endocytosis. Additionally, the multivalent nature of nanoparticles influenced cellular uptake. Specifically, nanoparticles with a higher valence internalized more rapidly and efficiently than those with a lower valence. Nanoparticles that selectively target and accumulate within diseased cells have the potential of minimizing drug degradation under physiological conditions, enhancing bioavailability at the tumor, improving the efficacy of the drug, and reducing toxicity from systemic biodistribution. Drug delivery through targeted nanoparticles was achieved by loading nanoparticles with silyl ether-modified gemcitabine prodrugs. Covalently reacting the prodrug into the nanoparticle matrix minimized drug loss, while the acid-sensitive silyl ether moiety enabled release of gemcitabine at a low pH. Targeted nanoparticles appeared to accumulate intracellularly, through TfR-mediated endocytosis, within acidic vesicles whose environment could trigger degradation of the prodrug and thus, release of gemcitabine. Leveraging the specificity of targeted nanoparticles and acid-sensitive silyl ether-based gemcitabine, targeted nanoparticles (IC50 = 1.8 × 10-2 nM) were far more potent than free gemcitabine (IC50 = 4.1 × 104 nM). Therefore, this system demonstrates the tremendous potential of targeted PRINT nanoparticles as advanced drug delivery agents
Shape-Specific Hydrogel Nanoparticles with Defined Composition and Surface Properties for Gene Silencing
No full textDiseases and disorders may be treated through RNA interference (RNAi), a natural post-transcriptional gene silencing event. Synthetic small interfering RNAs (siRNAs) may be designed to target specific genes for down-regulation in RNAi therapies. In the delivery of siRNA to target cells in vivo, numerous challenges are encountered such as susceptibility to degradation by RNases, clearance by the reticuloendothelial system, low internalization by cells, and endosomal escape. siRNA may be chemically modified or associated with lipid- or polymer-based particulate vehicles to enhance in vivo stability, increase bioavailability, improve transfection, facilitate accumulation in particular tissues, and enable cell-specific gene silencing. Independent control over the physicochemical properties of nanoparticles in the delivery of siRNA was enabled through a particle molding process that is a unique off-shoot of soft lithography known as PRINT® (Particle Replication in Non-wetting Templates) technology. Cationic hydrogel nanoparticles were tested using biocompatible poly(vinyl pyrrolidone)- and poly(ethylene glycol) (PEG)-based matrices for their ability to physically encapsulate and deliver siRNA to target cells. Effective gene silencing was observed in vitro using PEGylated hydrogel nanoparticles without inducing cytotoxicity. Functionalization of particles with maleic anhydride-derivatized ligands was pursued to produce a wholly acid-labile system capable of targeting the transferrin receptor, endosomal escape, and delivery of siRNA. To maximize retention of siRNA within hydrogel nanoparticles during systemic administration or functionalization with ligands, a pro-drug strategy was sought for covalent incorporation and triggered intracellular release of siRNA. Gene silencing efficiency and biocompatibility were optimized in the pro-drug siRNA system by screening the amine content of nanoparticles. When control cargos were implemented in the preparation of hydrogels, only target-specific, releasable siRNA cargo elicited gene knockdown. In effort to treat liver diseases, nanoparticles were functionalized with ligands targeting hepatocytes, cells of liver parenchyma implicated in diseases. Ligand-decorated nanoparticles were selectively internalized by hepatocytes in vitro and accumulated in hepatocytes in vivo. Hydrogel nanoparticles coated with ligands reduced target liver gene expression after administration to mice. Further investigation and exploration of this system will hopefully enable efficacious in vivo RNAi therapies in the treatment of numerous diseases.Doctor of Philosoph
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