Enhancing Chaotic Communication Performances by Manchester Coding

A numerical analysis of an optical chaotic transmission system, based on the synchronization of two chaotic lasers, in a master-slave closed loop configuration is presented. At the transmitter, the master chaotic wave is superposed on the information message; at the receiver, the message is recovered by subtracting the synchronized slave chaotic wave from the received signal. The performances are analyzed in terms of the Q-factor, considering two different message modulation formats: the nonreturn-to-zero and the Manchester coding. The Manchester coding shows enhanced performances due to the shift of the signal spectrum to higher frequencies.     

Ethyl oleate ozonide as an epoxidation tool of C60 and C70 fullerenes

When dissolved in ethyl oleate secondary ozonide, both C₆₀ and C₇₀ fullerenes undergo a series of epoxidation reactions. The pseudofirst-order kinetic rate constants of this process were determined spectrophotometrically at various temperatures and the activation energy for C₆₀ epoxidation through ethyl oleate ozonide was found at 25.9 kcal/mol. Furthermore, C₆₀ was found more reactive than C₇₀ with the ozonide. The kinetics rate constants of C₆₀ epoxidation with ethyl oleate ozonide were compared with the C₆₀ photo-oxidation and auto-oxidation determined in pure ethyl oleate. The epoxidation of fullerenes starts from the homolysis of the peroxide group of the 1,2,4-trioxolane ring of ethyl oleate secondary ozonide. Thus, it is suggested that fullerenes have a potential as decomposition agents of secondary ozonides in some technological applications.     

Surface modification of activated carbon fabric with ozone. Part 2: Thermal analysis with TGA-FTIR and DTA

Two samples of activated carbon fabrics (ACF) with very high surface area (>1300 to >1800 m²/g) fully ozonized in the part 1 of this study were analyzed by thermogravimetric analysis (TGA) coupled both with differential thermal analysis (DTA) and FT-IR spectroscopy (TGA-FTIR). The adsorbed water and the amount of oxygenated functional groups were determined. The ozonized ACF shows an exothermal decomposition at about 181–189°C which may be due at least in part to the decomposition of ozonide and/or peroxide groups. The TGA-FTIR has revealed that the main products released from the thermal decomposition are CO₂ followed by CO. Formic acid was detected only in correspondence to the exothermal transition at 181°C and was taken as a proof of the decomposition of secondary ozonides.     

Towards controlled cationic polymer growth from inorganic oxide defects: Directing the mechanism of polystyrene grafting from γ-irradiated silica

Most studies on surface-initiated controlled polymerizations for the synthesis of polymeric covalent organic-inorganic hybrid materials focus on chemical methods requiring specific modifications of the inorganic substrate. Few mechanistically-aware approaches have been undertaken towards exploiting the reactivity of defects induced by physical techniques such as ionizing radiations or UV–Vis light. Within this framework, we take grafted polymerization of styrene from γ-irradiated silica as a mechanistic testing ground where para- and diamagnetic silica defects are present, and polymerization proceeds through both radical and cationic mechanisms, resulting in a bimodal molecular weight distribution. We show that these mechanistic intricacies can be sorted out by resorting to the chemical arsenal developed in the last decades for controlled polymerizations. Specifically, we obtained a silica-polystyrene grafted material by cationic grafting from at 30 °C, a unimodal molecular weight distribution, and a relatively high molecular weight (Mn = 7.4 kDa) with a PDI of 1.68.     

A new route to graphene starting from heavily ozonized fullerenes: Part 3 – an electron spin resonance study

It is shown that graphite oxide (GO) and both heavily ozonized C₆₀ and C₇₀ fullerenes, known as “fullerene ozopolymers,” are paramagnetic materials with a very strong electron spin resonance (ESR) signal at room temperature. When thermally annealed, the paramagnetic centers are gradually lost in large part. This occurs at 350°C in the case of GO, while for fullerene ozopolymers, a higher temperature is required, reaching the same results in the end. The half-width of ESR signal is linked to the distribution of paramagnetic centers. Once again, striking analogies were found in the half-width of the ESR signal measured on GO and fullerene ozopolymers, at least in the temperature range of 25–450°C. Similarly, the same g-factor values, which are diagnostic for understanding the chemical nature of paramagnetic centers, were found on both GO and fullerene ozopolymers in all ranges of temperature considered.     

The antioxidant capacity of complex mixtures by kinetic analysis of crocin bleaching inhibition

The capability of a compound or of a mixture of compounds to quench peroxyl radicals was measured by analyzing the kinetics of the competition of a parallel reaction where peroxyl radicals bleach the carotenoid crocin. This kinetic approach, originally described for the analysis of antioxidants reacting with hydroxyl radicals in water, was modified by both decreasing the polarity of the solvent, thus allowing the analysis of lipophilic compounds, and by substituting a source of peroxyl radicals for the hydroxyl radical generating system. Single compounds as well as complex mixtures were analyzed by kinetic data processing. Overall antioxidant capacity, relative to that of α-tocopherol or of its soluble analog Trolox C, was calculated. As examples of the use of this test, the antioxidant capacities of a crude rosemary extract, Maillard reaction products, and virgin olive oils were measured.     

Epigenetic and Genetic Factors Related to Curve Progression in Adolescent Idiopathic Scoliosis: A Systematic Scoping Review of the Current Literature

Adolescent idiopathic scoliosis (AIS) is a progressive deformity of the spine. Scoliotic curves progress until skeletal maturity leading, in rare cases, to a severe deformity. While the Cobb angle is a straightforward tool in initial curve magnitude measurement, assessing the risk of curve progression at the time of diagnosis may be more challenging. Epigenetic and genetic markers are potential prognostic tools to predict curve progression. The aim of this study is to review the available literature regarding the epigenetic and genetic factors associated with the risk of AIS curve progression. This review was carried out in accordance with Preferential Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. The search was carried out in January 2022. Only peer-reviewed articles were considered for inclusion. Forty studies were included; fifteen genes were reported as having SNPs with significant association with progressive AIS, but none showed sufficient power to sustain clinical applications. In contrast, nine studies reporting epigenetic modifications showed promising results in terms of reliable markers. Prognostic testing for AIS has the potential to significantly modify disease management. Most recent evidence suggests epigenetics as a more promising field for the identification of factors associated with AIS progression, offering a rationale for further investigation in this field.     

Polarized Backward Raman Amplification in Randomly Birefringent Fibers

In this paper, a model describing the vector interaction of an intense backward-propagating Raman pump and a weak forward-propagating Stokes signal in randomly birefringent fibers is proposed. The model accounts for the losses, the Raman interaction, and the linear and nonlinear birefringence. Realistic characteristics of the backward-propagation-birefringence vector have been originally accounted for. Numerical solutions show that polarized-backward-Raman amplifiers can have gain fluctuations larger than previously reported because of linear- and nonlinear-birefringence effects. Moreover, the gain mean depends on the signal and pump state of polarization imposed at the amplifier input or output. Simple formulas are derived for predicting the gain mean when nonlinear effects can be neglected     

Ozonolysis of α-PINENE, β-PINENE,d- and l-Turpentine Oil Studied by Chirooptical Methods; Some Implications on the Atmospheric Chemistry of Biogenic Volatile Organic Compounds

The main constituents of biogenic volatile organic compounds (BVOC) released in the atmosphere from vegetation are terpenes. The most common terpenes are α-pinene and β-pinene. These molecules react with ozone, forming oxidized derivatives which have low vapor pressure and which nucleate into secondary organic aerosol (SOA). Such aerosol-forming reactions have been simulated in the gas phase on laboratory scale with the visualization of the formation of SOA. Electronic absorption spectroscopy shows that the UV peak of pinenes at 205 nm is shifted to 225 nm during and after ozonolysis and is accompanied by a series of spectral features in the near infrared region (between 850 nm and 1100 nm). Optical rotatory dispersion (ORD) spectra were recorded on pure β(+)pinene and β(?)pinene. After ozonolysis β-pinene enantiomers are converted into nopinone enantiomers. The ORD spectra of both (?)nopinone and (+)nopinone respectively were recorded. The former showed a peak at 453 nm, an inflection point at 430 nm and a trough at 405 nm. The ORD spectrum of (?)-nopinone appears completely symmetrical to that of (+)nopinone. Thus, ORD spectroscopy can distinguish between BVOC and oxidized BVOC quite easily at least in the case of β-pinene. The ORD spectra of α-pinene enantiomers are different from those of β-pinene enantiomers and although the ORD spectra of ozonized α-pinene are not easily distinguishable from those of the primary compounds, they are completely different from those of ozonized β-pinene enantiomers. A reasonable natural model of BVOC is offered by l- and d-turpentine oil whose composition reflects that of the BVOC from conifer forests. The ORD spectra of ozonized l- and d-turpentine has permitted to distinguish between the levorotatory and dextrorotatory oxidation products and showing the ketone peak at about 367–380 nm, thus permitting in a real model to distinguish between primary BVOC (turpentine) and oxidized BVOC (or SOA) corresponding to ozonized turpentine. It has been proposed that ORD spectra in the gas phase could be used to detect chiral BVOC and oxidized chiral BVOC.