1,721,000 research outputs found
AGGIUNTA DI UN SALE IONICO A SOLUZIONI POLIMERICHE CONCENTRATESEMIDILUITE: EFFETTI SU COMPORTAMENTO REOLOGICO ED ELETTROFILATURA
No full textIn questo lavoro si studia l’effetto del contenuto di ferro tricloruro (FeCl3) sul comportamento reologico e sull’elettrofilatura di una soluzione semidiluita di poliammide 6 (PA6) in acido formico. La caratterizzazione del comportamento reologico estensionale mediante rottura autocontrollata di un filamento mostra che l’elasticità della soluzione diminuisce al crescere del contenuto di sale a causa della formazione di complessi ingombranti con i gruppi ammidici della PA6 che schermano i legami a idrogeno intermolecolari. Contemporaneamente, si osserva un incremento della viscosità a taglio, tanto da rendere la risposta viscosa dominante per una concentrazione del 6.5 wt%. A tale concentrazione l’esito dell’elettrofilatura è una fibra significativamente difettosa, malgrado la concentrazione di PA6 in soluzione sia prossima a quella critica per la formazione degli entanglement.In this work the effect of iron(III) chloride content on the rheological behaviour and electrospinning of a solution containing polyamide 6 (PA6) and formic acid is studied. The extensional rheology characterization is carried out with the self-thinning capillary breakup technique and shows that the solution elasticity decreases with increasing salt content. This is due to the formation of complexes with the amide groups of PA6 backbones that causes the scission of intermolecular hydrogen bonds. Conversely, the shear viscosity increases with salt content to such an extent that the viscous component becomes predominant at 6.5 wt%. At this concentration, the electrospun fibres show severely inhomogeneous structures, despite PA6 concentration is close to the entanglement critical concentration
Thermostable engineered enzyme
No full textThe invention relates to an engineered PETase enzyme comprises an amino acid sequence having at least 70% or 80%, 90%, 95%, 99% or 100% sequence identity to SEQ ID NO.1. Preferably, the PETase enzyme comprises SEQ ID NO.1 with at least four mutations. The invention also refers to a composition and to a method for decomposing plastics
Recent Approaches to the Identification of Novel Microtubule-Targeting Agents
Full text linkMicrotubules are key components of the eukaryotic cytoskeleton with essential roles in cell division, intercellular transport, cell morphology, motility, and signal transduction. They are composed of protofilaments of heterodimers of alpha-tubulin and beta-tubulin organized as rigid hollow cylinders that can assemble into large and dynamic intracellular structures. Consistent with their involvement in core cellular processes, affecting microtubule assembly results in cytotoxicity and cell death. For these reasons, microtubules are among the most important targets for the therapeutic treatment of several diseases, including cancer. The vast literature related to microtubule stabilizers and destabilizers has been reviewed extensively in recent years. Here we summarize recent experimental and computational approaches for the identification of novel tubulin modulators and delivery strategies. These include orphan small molecules, PROTACs as well as light-sensitive compounds that can be activated with high spatio-temporal accuracy and that represent promising tools for precision-targeted chemotherapy
Photochromic polymer as a versatile tool for device based on switchable absorption and other optical properties
No full textModeling absorbance-modulation optical lithography in photochromic films
No full textA kinetic model describing the conversion of a photochromic layer under complex illumination conditions is applied to absorbance-modulation optical lithography to determine the influence of the material characteristics on the confinement to subdiffraction dimensions of the transmitted dose. We show that the most important parameters are the intensity ratio between the confining and writing beams, the overall absorption at the writing wavelength, the relative absorption coefficients, and the photoreaction quantum yields at the two wavelengths. As the confining beam ultimately determines the transferred dose pattern, we conclude that the modulation of the writing beam is not strictly necessary to produce subwavelength apertures
Photochromism into optics: Opportunities to develop light-triggered optical elements
No full textOpportunities to apply photochromism in smart optics are highlighted. The reversible light-triggered switching in UV-vis absorption and in the refractive index can be exploited to develop rewritable optical elements, specifically tunable masks, amplitude holograms and volume gratings. Description of the configuration and performance of the optical devices with possible open issues is preceded by a discussion dealing with the molecular features that provide a strong modulation of the material properties which is required for a convenient functioning of the device
Kinetics of Photochromic Conversion at the Solid State:Quantum Yield of Dithienylethene-Based Films
No full textQuantum yield is one of the most important properties of photochromic systems. Unfortunately, a lack of data at the solid state exists, because measurements are intrinsically not straightforward. A kinetic model describing the conversion of the photoactive species is reported and both analytic and numeric solutions are provided according to relevant cases. The model is then applied to measure the quantum yield of dithienylethene-based polymers; the ring-opening quantum yield is measured for different laser beam profiles (i.e., Gaussian and uniform) and at different wavelengths, showing an increased value with increasing photon energy
Light-Based Anti-Biofilm and Antibacterial Strategies
Full text linkBiofilm formation and antimicrobial resistance pose significant challenges not only in clinical settings (i.e., implant-associated infections, endocarditis, and urinary tract infections) but also in industrial settings and in the environment, where the spreading of antibiotic-resistant bacteria is on the rise. Indeed, developing effective strategies to prevent biofilm formation and treat infections will be one of the major global challenges in the next few years. As traditional pharmacological treatments are becoming inadequate to curb this problem, a constant commitment to the exploration of novel therapeutic strategies is necessary. Light-triggered therapies have emerged as promising alternatives to traditional approaches due to their non-invasive nature, precise spatial and temporal control, and potential multifunctional properties. Here, we provide a comprehensive overview of the different biofilm formation stages and the molecular mechanism of biofilm disruption, with a major focus on the quorum sensing machinery. Moreover, we highlight the principal guidelines for the development of light-responsive materials and photosensitive compounds. The synergistic effects of combining light-triggered therapies with conventional treatments are also discussed. Through elegant molecular and material design solutions, remarkable results have been achieved in the fight against biofilm formation and antibacterial resistance. However, further research and development in this field are essential to optimize therapeutic strategies and translate them into clinical and industrial applications, ultimately addressing the global challenges posed by biofilm and antimicrobial resistance
Photochromic materials for holography: issues and constraints
No full textPhotochromic materials can find application in holography, thanks to the peculiar possibility to change reversibly their transparency in the visible (amplitude holography) and their refractive index in the near infrared region (phase holography). The main advantages of such materials are rewritability and self-development. A large change of the key property is crucial to obtain efficient devices and some strategies are followed, accordingly. Production of the holograms have open important issues regarding the film thickness and the nonlinear response to light, because of the strong absorption of the writing light by the material. Results related to these topics, mainly focused on diarylethene-based materials, are reported
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