Unraveling the mechanism of the photodeprotection reaction of 8-bromo- and 8-chloro-7-hydroxyquinoline caged acetates

Photoremovable protecting groups (PPGs) when conjugated to biological effectors forming "caged compounds" are a powerful means to regulate the action of physiologically active messengers in vivo through 1-photon excitation (1PE) and 2-photon excitation (2PE). Understanding the photodeprotection mechanism is important for their physiological use. We compared the quantum efficiencies and product outcomes in different solvent and pH conditions for the photolysis reactions of (8-chloro-7-hydroxyquinolin-2-yl)methyl acetate (CHQ-OAc) and (8-bromo-7-hydroxyquinolin-2-yl)methyl acetate (BHQ-OAc), representatives of the quinoline class of phototriggers for biological use, and conducted nanosecond time-resolved spectroscopic studies using transient emission (ns-EM), transient absorption (ns-TA), transient resonance Raman (ns-TR(2)), and time-resolved resonance Raman (ns-TR(3)) spectroscopies. The results indicate differences in the photochemical mechanisms and product outcomes, and reveal that the triplet excited state is most likely on the pathway to the product and that dehalogenation competes with release of acetate from BHQ-OAc, but not CHQ-OAc. A high fluorescence quantum yield and a more efficient excited-state proton transfer (ESPT) in CHQ-OAc compared to BHQ-OAc explain the lower quantum efficiency of CHQ-OAc relative to BHQ-OAc.     

Porous silicon-based optical biosensors and biochips

Porous silicon multilayered microstructures have unique optical and morphological properties that can be exploited in chemical and biological sensing. The large specific surface of nanostructured porous silicon can be chemically modified to link different molecular probes (DNA strands, enzymes, proteins and so on), which recognize the target analytes, in order to enhance the selectivity and specificity of the sensor device. We designed fabricated and characterized several photonic porous silicon-based structures, which were used in sensing some specific molecular interactions. The next step is the integration of the porous silicon-based optical transducer in biochip devices: at this aim, we have tested an innovative anodic bonding process between porous silicon and glass, and its compatibility with the biological probes.     

Recovery of tritium obtained as a by-product in the production of fluorine-18

For samples of irradiated natural and enriched (95%) Li₂CO₃, normal distillation to dryness of the alumina column eluates permits recuperation of approximately 80% of the tritium. The distilled samples were concentrated by electrolysis and a subsequent vacuum distillation resulted in a tritium enrichment of the order of 30%. The enriched samples were used to prepare sealed, calibrated sources, with different levels of tritium radioactivity, to be used as standards for the determination of tritium in unknown samples using liquid scintillation.     

Microneedles-based electrochemical sensors: New tools for advanced biosensing

Electrochemical biosensors are used worldwide as analytical tools from laboratory applications to market products. The performance of electrochemical sensing can be boosted by adopting the microneedle (MN) geometry as an innovative configuration of standard electrodes. MNs can be miniaturized, easily functionalized, and properly designed for specific aim monitoring, but most of all, they allow a low invasive controlling tool for growth and for environment influence in plant and a painless door to human body fluids where target analytes can be detected, overcoming the natural barrier of the skin. In this review, the very recent developments in MN-based electrochemical biosensing published in the literature are summarized.     

Langmuir-Blodgett film of hydrophobin protein from Pleurotus ostreatus at the air-water interface

We present results concerning the formation of Langmuir-Blodgett (LB) films of a class I hydrophobin from Pleurotus ostreatus at the air-water interface, and their structure as Langmuir-Blodgett (LB) films when deposited on silicon substrates. LB films of the hydrophobin were investigated by atomic force microscopy (AFM). We observed that the compressed film at the air-water interface exhibits a molecular depletion even at low surface pressure. In order to estimate the surface molecular concentration, we fit the experimental isotherm with Volmer's equation describing the equation of state for molecular monolayers. We found that about (1)/ 10 of the molecules contribute to the surface film formation. When transferred on silicon substrates, compact and uniform monomolecular layers about 2.5 nm thick, comparable to a typical molecular size, were observed. The monolayers coexist with protein aggregates, under the typical rodlet form with a uniform thickness of about 5.0 nm. The observed rodlets appear to be a hydrophilic bilayer and can then be responsible for the surface molecular depletion.     

Role of a Measurement Plane to Monitor and Manage QOS in Optical Access Networks

In this work, we propose a measurement plane for Software Defined Networking (SDN) architectures for monitoring the network performance and supporting the orchestrator in managing the optical link resources. Concerning the measurement plane, we consider two models that we adopted in other contests: Misurainternet and mPlane. However, due to better scalability, the tests reported in this paper refer to mPlane that has been used in a SDN environment based on Fiber to the X (FTTX) accesses, with procedures of the central unit (orchestrator) that automatically manages GbE links in a regional network. The choices of the orchestrator are based on information received by a reasoner that analyzes the network performance elaborating data detected by active and passive probes. The mPlane-SDN architecture is tested in field measurements concerning FTTX accesses and in Lab to verify the resource allocations in case of traffic congestion. Furthermore, we also show the potentiality of our architecture to evolve toward a distributed controller approach with important advantages for telecom operator strategies.     

Disulfide Bond Replacement with 1,4- and 1,5-Disubstituted [1,2,3]-Triazole on C-X-C Chemokine Receptor Type 4 (CXCR4) Peptide Ligands: Small Changes that Make Big Differences

Here we investigated the structural and biological effects ensuing from the disulfide bond replacement of a potent and selective C-X-C chemokine receptor type 4 (CXCR4) peptide antagonist, with 1,4- and 1,5- disubstituted 1,2,3-triazole moieties. Both strategies produced candidates that showed high affinity and selectivity against CXCR4. Notably, when assessed for their ability to modulate the CXCL12-mediated cell migration, the 1,4-triazole variant conserved the antagonistic effect in the low-mid nanomolar range, while the 1,5-triazole one displayed the ability to activate the migration, becoming the first in class low-molecular-weight CXCR4 peptide agonist. By combining NMR and computational studies, we provided a valuable model that highlighted differences in the interactions of the two peptidomimetics with the receptor that could account for their different functional profile. Finally, we envisage that our findings could be translated to different GPCR-interacting peptides for the pursuit of novel chemical probes that could assist in dissecting the complex puzzle of this fundamental class of transmembrane receptors.     

Preliminary evidence that both blue and red light can induce alertness at night

Background  

A variety of studies have demonstrated that retinal light exposure can increase alertness at night. It is now well accepted that the circadian system is maximally sensitive to short-wavelength (blue) light and is quite insensitive to long-wavelength (red) light. Retinal exposures to blue light at night have been recently shown to impact alertness, implicating participation by the circadian system. The present experiment was conducted to look at the impact of both blue and red light at two different levels on nocturnal alertness. Visually effective but moderate levels of red light are ineffective for stimulating the circadian system. If it were shown that a moderate level of red light impacts alertness, it would have had to occur via a pathway other than through the circadian system.     

Quality of Service Control Based on Virtual Private Network Services in a Wide Area Gigabit Ethernet Optical Test Bed

Abstract

We report an experimental investigation about the Virtual Private LAN Service technique to guarantee the quality of service in the metro/core network and also in the presence of access bandwidth bottleneck. We also show how the virtual private network can be set up for answering to a user request in a very fast way. The tests were performed in a GMPLS test bed with GbE core routers linked with long (tens of kilometers) GbE G.652 fiber links.     

Fast Restoration Based on Alternative Wavelength Paths in a Wide Area Optical IP Network

In this article we describe an experimental investigation of IP network restoration based on wavelength recovery. We propose a procedure for metro and wide area gigabit Ethernet networks that allows us to route the wavelength in case of link failure to another existing link by exploiting wavelength division multiplexing in the fiber. Such a procedure is obtained by means of an optical switch that is managed by a loss-of-light signal that is generated by a router in case of link failure. Such a method has been tested in an IP network consisting of three core routers with optical gigabit Ethernet interfaces connected by means of 50-km-long single-mode fibers between Rome and Pomezia. Compared with other conventional restoration techniques, such as OSPF and MPLS, our method -in very fast (20 ms) and is compatible with real-time TV services and low-cost chips.