Singlet Oxygen Generation Enhanced by Silver-Pectin Nanoparticles

We demonstrate the potential application of silver-pectin nanoparticles on photodynamic therapy, on a solution-base platform. Photodynamic therapy is a medical technique which uses a combination of photosensitizing drugs and light to induce selective damage on the target tissue, by electronically excited and highly reactive singlet state of oxygen. Metal enhanced singlet oxygen generation in riboflavin water solution with silver-pectin nanoparticles was observed and quantified. Here 13 nm silver nanospheres enclosed by a pectin layer were synthesized and it interaction with riboflavin molecule was analyzed. Pectin, a complex carbohydrate found in plants primary cell walls, was used to increase the biocompatibility of the silver nanoparticles and to improve metal enhanced singlet oxygen generation (28.5 %) and metal-enhanced fluorescence (30.7 %) processes at room temperature. The singlet oxygen sensor fluorescent green reagent was used to quantify the enhancement of the riboflavin singlet oxygen production induced by the silver colloid. We report a 1.7-fold increase of riboflavin emission and a 1.8-fold enhancement of singlet oxygen production.     

Temperature‐dependent Raman spectroscopy study in MoO3 nanoribbons

This paper reports a study of vibrational, structural and morphological properties of molybdenum oxide nanoribbons. Temperature‐dependent Raman spectroscopy measurements in MoO₃ nanoribbons revealed morphological changes in the 150–350 °C temperature range. No structural phase transitions were observed, thus showing that the orthorhombic phase is stable from room temperature (nanoribbons) up to 650 °C (bulk‐like phase) where large plates have been formed by the coalescence of the nanoribbons. The interpretation of temperature‐dependent Raman data (wavenumber and linewidths) is supported by scanning electron microscopy that is used to directly probe the morphological changes in MoO₃ samples. The observed phenomena in the Raman data for MoO₃ nanoribbons can be applied to other nanomaterials. Copyright © 2012 John Wiley & Sons, Ltd.     

Photoluminescence from germanate glasses containing silicon nanocrystals and erbium ions

We report the first observation of photoluminescence enhancement in Er³⁺ doped GeO₂–Bi₂O₃ glasses containing silicon nanocrystals (Si-NCs) excited by a laser operating at 980 nm. The growth of ≈200% in the intensity of the Er³⁺ transition ⁴S_3/2→⁴I_15/2 (545 nm) and of ≈100% for transitions ²H_11/2→⁴I_15/2 (525 nm), ⁴F_9/2→⁴I_15/2 (660 nm), and ⁴I_5/2→⁴I_13/2 (1530 nm) was observed in comparison with a reference sample that does not contain Si-NCs. The results open a new road for obtaining efficient Stokes and anti-Stokes emissions in germanate composites doped with rare-earth ions.     

Impact of first-year mathematics study groups on the retention and graduation of engineering students

Many interventions have been proposed to improve the retention and graduation rates of engineering students. One such intervention is to use study groups for first-year college students; such groups provide a structured environment in which the students can learn course material from each other outside of class and can provide the students with a sense of community. In this paper, we report on the impacts fostered by study groups in first-year mathematics courses on the odds of retaining and graduating engineering students. Students who participated in the study groups are compared to students of similar academic preparation who did not participate in such groups. It is found that student participation in study groups is significantly associated with the higher odds of being retained in engineering studies through the first 3 years of college. The results reported here are not as certain for the effect of study group participation on 5-year graduation odds for engineering students and some possible reasons for this are discussed.     

Intravitreal NGF administration counteracts retina degeneration after permanent carotid artery occlusion in rat

Background  

The neurotrophin nerve growth factor (NGF) is produced by different cell types in the anterior and posterior eye, exerting a neuroprotective role in the adult life. The visual system is highly sensitive to NGF and the retina and optic nerve provides suitable subjects for the study of central nervous system degeneration. The model of bilateral carotid occlusion (two-vessel occlusion, 2VO) is a well-established model for chronic brain hypoperfusion leading to brain capillary pathology, to retina and optic nerve degeneration. In order to study if a single intravitreal injection of NGF protects the retina and the optic nerve from degeneration during systemic circulatory diseases, we investigated morphological and molecular changes occurring in the retina and optic nerve of adult rats at different time-points (8, 30 and 75 days) after bilateral carotid occlusion.     

Speckle interferometry, fibre optic sensors and laser induced ultrasounds as solutions to industrial demands

Industrial operators have been taking interest in optical diagnostics through years. Optical methods are mainly well appreciated for their attitude to be used as non-contact and non-invasive techniques. The paper presents three examples of applications carried-out by researchers of Centro Elettrotecnico Sperimentale Italiano (CESI) in collaboration with people working in industrial fields. The first part shows the applications of speckle interferometry to measure residual stresses in association with the traditional blind-hole drilling, while the second part presents the installation of fibre optic sensors in a power plant for monitoring possible overheating to avoid fires and finally the last presentation outlines a particular application in the field of laser generated ultrasounds that is the monitoring of the variation of ultrasonic speed propagation due to residual stresses.     

Pharmacological activities of a propylthiouracil compound structurally modified by coordination with copper(II)

For the first time, pharmacological activities for propylthiouracil (actually used as antithyroid drug) were determined. In addition, a new propylthiouracil copper(II) complex ([Cu(PTU)₂]₂) was synthesized and characterized by FTIR, EPR, UV–visible, and diffuse reflectance spectroscopies including elemental analysis, dissolution profiles, and stability studies. Taking into account the correlation between Graves’ disease and the formation of reactive oxygen species (ROS) and other free radicals, the ligand and the complex were tested for their antioxidant effects on O₂^·? and OH^· radicals. A significant increase in the disruption of OH^· radical was observed for PTU and its copper(II) complex, but neither of them have the ability to dismutate the O₂^·? radical. Antimicrobial activities were also determined observing that the complex is very active against Gram-positive bacteria. In addition, the ability of PTU and its complex to inhibit acid and alkaline phosphatases were analyzed. Results showed that PTU had no effect, while the complex behaved as a potent ALP (alkaline phosphatases) inhibitor. Finally, albumin interaction experiments denoted high affinity towards the complex in contrast with PTU with a constant binding value two hundred times higher than the ligand and bearing two binding sites. Based on this study, it has been hypothesized that ([Cu(PTU)₂]₂ would be a promising candidate for further evaluation as an antioxidant, antimicrobial and phosphatase alkaline inhibitor agent.