61 research outputs found
Enhancing the Antibacterial Properties of Chitosan Coatings: Ag@Chitosan and Chitosan from Insects
In this study, the electrophoretic deposition (EPD) technique was used to prepare chitosanbased
coatings with enhanced antibacterial activity suitable for bone implant applications. We
designed, prepared, and compared the physico-chemical and biological properties of coatings obtained
with commercial chitosan, chitosan enriched with silver nanoparticles, and chitosan obtained
from insects. With the aim to consider the issue of sustainability, silver nanoparticles were directly
prepared in the chitosan solution by laser ablation via a liquid technique, avoiding the use of chemicals
and limiting the production of wastes. Moreover, a sustainable source of chitosan, such as
Hermetia Illucens exuviae, was considered. The EPD process was optimized by adjusting parameters
like voltage and deposition time to achieve ideal coating thickness and adhesion. The prepared
films were characterized by spectroscopic and microscopic techniques such as SEM, XRD, and FTIR.
Antimicrobial tests against E. coli and S. aureus revealed that silver nanoparticles enhanced the antibacterial
properties of the polymer, whereas the biological evaluation using the WST8 test on MG63
human osteoblast-like cells showed that all coatings were non-toxic. Finally, chitosan obtained from
insect showed comparable properties with respect to the commercial polymer, suggesting it could
replace seafood-derived chitosan in biomedical applications, whereas the Ag@chitosan composite
demonstrated superior antibacterial activity without compromising its biocompatibility
LIPSS Applied to Wide Bandgap Semiconductors and Dielectrics: Assessment and Future Perspectives
With the aim of presenting the processes governing the Laser-Induced Periodic Surface
Structures (LIPSS), its main theoretical models have been reported. More emphasis is given to
those suitable for clarifying the experimental structures observed on the surface of wide bandgap
semiconductors (WBS) and dielectric materials. The role played by radiation surface electromagnetic
waves as well as Surface Plasmon Polaritons in determining both Low and High Spatial Frequency
LIPSS is briefly discussed, together with some experimental evidence. Non-conventional techniques
for LIPSS formation are concisely introduced to point out the high technical possibility of enhancing
the homogeneity of surface structures as well as tuning the electronic properties driven by point
defects induced in WBS. Among these, double- or multiple-fs-pulse irradiations are shown to be
suitable for providing further insight into the LIPSS process together with fine control on the formed
surface structures. Modifications occurring by LIPSS on surfaces of WBS and dielectrics display high
potentialities for their cross-cutting technological features and wide applications in which the main
surface and electronic properties can be engineered. By these assessments, the employment of such
nanostructured materials in innovative devices could be envisaged
Protein Isoaspartate Methyltransferase Prevents Apoptosis Induced by Oxidative Stress in Endothelial Cells: Role of Bcl-Xl Deamidation and Methylation
BACKGROUND:Natural proteins undergo in vivo spontaneous post-biosynthetic deamidation of specific asparagine residues with isoaspartyl formation. Deamidated-isomerized molecules are both structurally and functionally altered. The enzyme isoaspartyl protein carboxyl-O-methyltransferase (PCMT; EC 2.1.1.77) has peculiar substrate specificity towards these deamidated proteins. It catalyzes methyl esterification of the free alpha-carboxyl group at the isoaspartyl site, thus initiating the repair of these abnormal proteins through the conversion of the isopeptide bond into a normal alpha-peptide bond. Deamidation occurs slowly during cellular and molecular aging, being accelerated by physical-chemical stresses brought to the living cells. Previous evidence supports a role of protein deamidation in the acquisition of susceptibility to apoptosis. Aim of this work was to shed a light on the role of PCMT in apoptosis clarifying the relevant mechanism(s). METHODOLOGY/PRINCIPAL FINDINGS:Endothelial cells transiently transfected with various constructs of PCMT, i.e. overexpressing wild type PCMT or negative dominants, were used to investigate the role of protein methylation during apoptosis induced by oxidative stress (H(2)O(2); 0.1-0.5 mM range). Results show that A) Cells overexpressing "wild type" human PCMT were resistant to apoptosis, whereas overexpression of antisense PCMT induces high sensitivity to apoptosis even at low H(2)O(2) concentrations. B) PCMT protective effect is specifically due to its methyltransferase activity rather than to any other non-enzymatic interactions. In fact negative dominants, overexpressing PCMT mutants devoid of catalytic activity do not prevent apoptosis. C) Cells transfected with antisense PCMT, or overexpressing a PCMT mutant, accumulate isoaspartyl-containing damaged proteins upon H(2)O(2) treatment. Proteomics allowed the identification of proteins, which are both PCMT substrates and apoptosis effectors, whose deamidation occurs under oxidative stress conditions leading to programmed cell death. These proteins, including Hsp70, Hsp90, actin, and Bcl-xL, are recognized and methylated by PCMT, according to the general repair mechanism of this methyltransferase. CONCLUSION/SIGNIFICANCE:Apoptosis can be modulated by "on/off" switch partitioning the amount of specific protein effectors, which are either in their active (native) or inactive (deamidated) molecular forms. Deamidated proteins can also be functionally restored through methylation. Bcl-xL provides a case for the role of PCMT in the maintenance of functional stability of this antiapoptotic protein
A study of CP violation in B-+/- -> DK +/- and B-+/- -> D pi(+/-) decays with D -> (KSK +/-)-K-0 pi(-/+) final states
A first study of CP violation in the decay modes and , where labels a or meson and labels a or meson, is performed. The analysis uses the LHCb data set collected in collisions, corresponding to an integrated luminosity of 3 fb. The analysis is sensitive to the CP-violating CKM phase through seven observables: one charge asymmetry in each of the four modes and three ratios of the charge-integrated yields. The results are consistent with measurements of using other decay modes
Measurement of Upsilon production in collisions at root s=2.76 TeV
The production of , and mesons decaying into the dimuon final state is studied with the LHCb detector using a data sample corresponding to an integrated luminosity of 3.3 collected in proton-proton collisions at a centre-of-mass energy of TeV. The differential production cross-sections times dimuon branching fractions are measured as functions of the transverse momentum and rapidity, over the ranges $p_{\rm T} Upsilon(1S) X) x B(Upsilon(1S) -> mu+mu-) = 1.111 +/- 0.043 +/- 0.044 nb, sigma(pp -> Upsilon(2S) X) x B(Upsilon(2S) -> mu+mu-) = 0.264 +/- 0.023 +/- 0.011 nb, sigma(pp -> Upsilon(3S) X) x B(Upsilon(3S) -> mu+mu-) = 0.159 +/- 0.020 +/- 0.007 nb, where the first uncertainty is statistical and the second systematic
Study of forward Z + jet production in pp collisions at âs=7 TeV
A measurement of the +jet production cross-section in collisions at a centre-of-mass energy TeV is presented. The analysis is based on an integrated luminosity of recorded by the LHCb experiment. Results are shown with two jet transverse momentum thresholds, 10 and 20 GeV, for both the overall cross-section within the fiducial volume, and for six differential cross-section measurements. The fiducial volume requires that both the jet and the muons from the Z boson decay are produced in the forward direction (). The results show good agreement with theoretical predictions at the second-order expansion in the coupling of the strong interaction.A measurement of the +jet production cross-section in collisions at a centre-of-mass energy TeV is presented. The analysis is based on an integrated luminosity of recorded by the LHCb experiment. Results are shown with two jet transverse momentum thresholds, 10 and 20 GeV, for both the overall cross-section within the fiducial volume, and for six differential cross-section measurements. The fiducial volume requires that both the jet and the muons from the Z boson decay are produced in the forward direction (). The results show good agreement with theoretical predictions at the second-order expansion in the coupling of the strong interaction
Emission spectra investigation of a space resolved fs/ns dual pulse LIBS configuration technique
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