Photophysical Properties of some 1,3,4-Oxadiazole Derivatives Containing Phenolphtalein,Fluorene and Bisphenol A Units

The photophysical properties of the three 1,3,4-oxadiazole derivatives containing fluorene (Ox-FL); fluorene and phenolphtaleine (Ox-FL-FF); or fluorene and bisphenol A (Ox-FL-BPA) moieties in the main chain were investigated by the fluorescence and absorption spectroscopy in different solvents and in the solid state. The electronic absorption spectra included a strong absorption band located in the 270–395 nm region, with a maxima around at 302 nm. The fluorescence excitation spectra were also characterized by one broad band, appearing in the wavelength range of 220–340 nm. All samples displayed the emission bands around 356–373 nm and exhibit high quantum yields ranged from 31.61 to 90.77%, in chloroform solution. The sensitivity of the emission spectra on medium characteristics (polarity, acidity and basicity) were evaluated by using the Catalan solvent scale and the fluorescence titration with a dilute acid solution.     

Styrene‐butadiene rubber synthesized by anionic polymerization

In this paper we report on the copolymerization of styrene with butadiene in cyclohexane as solvent. Some experiments were also done using toluene as a solvent in order to check the influence of this solvent on the polydispersity index of the copolymers obtained, n‐ Butyllithium (BuLi) was used as initiator, while methyl‐tert‐butyl ether (MTBE) was used as an active center modifier. Reaction parameters such as polymerization temperature, the [MTBE]/[BuLi] molar ratio and the nature of solvent were studied in relation to their effects on the copolymerization rate, the randomness of the polymer and the microstructure of the butadiene units incorporated.     

Anti-Inflammatory and Antioxidant Properties of Carvacrol and Magnolol,in Periodontal Disease and Diabetes Mellitus

Periodontal disease and diabetes mellitus are two pathologies that are extremely widespread worldwide and share the feature of chronic inflammation. Carvacrol is a phenolic monoterpenoid, produced by a variety of herbs, the most well-known of which is Origanum vulgare. Magnolol is a traditional polyphenolic compound isolated from the stem bark of Magnolia officinalis, mainly used in Chinese medicine. The purpose of this paper is to review the therapeutic properties of these bioactive compounds, in the treatment of periodontitis and diabetes. Based on our search strategy we conducted a literature search in the PubMed and Google Scholar databases to identify studies. A total of one hundred eighty-four papers were included in the current review. The results show that carvacrol and magnolol have anti-inflammatory, antioxidant, antimicrobial, anti-osteoclastic, and anti-diabetic properties that benefit both pathologies. Knowledge of the multiple activities of carvacrol and magnolol can assist with the development of new treatment strategies, and the design of clinical animal and human trials will maximize the potential benefits of these extracts in subjects suffering from periodontitis or diabetes.     

Anionic and ionic coordinative polymerization of L-lactide

The potassium naphthalenide complex with 18-crown-6 is able to initiate anionic polymerization of L -lactide at 20°C. This type of anionic initiator does not have to be removed from the polymer as it does not affect metabolic processes. The ionic polymerization of L -lactide with an initiator based on Zn(II) acetyl acetonate, which is fairly stable, has been investigated. It has been found that this process leads to the corresponding polyesters, at high yields. © 1998 John Wiley & Sons, Ltd.     

Exploring the Research Progress about the Applications of Cyclodextrins and Nanomaterials in Electroanalysis

Cyclodextrins and nanomaterials are widely used in the achievement of powerful platforms in supramolecular chemistry and nanotechnology. The relatively hydrophobic internal cavity of the CDs selectively retains molecules having the proper geometry, while the hydrophilic exterior allows CDs to improve the dispersibility and molecular recognition. The nanomaterials provide higher surface area, good conductivity, and electrocatalytic effect. The use of nanomaterials and CDs in electrochemical sensors’ design allows the development of a large variety of devices, explaining the increasing number of papers in the last years that are discussed in this review.     

Mapping the Distribution of Melanin Concentration in Different Fitzpatrick Skin Types Using Hyperspectral Imaging Technique

Measuring skin melanin concentration in order to assess skin phototype according to Fitzpatrick's classification is a constant research goal. In this study, a new approach for assessing skin melanin concentration based on hyperspectral imaging combined with an appropriate analytical model that exploits specific spectral bands to generate maps of melanin content distribution on different Fitzpatrick skin phototypes is presented. Hyperspectral images from the proximal inner side of the forearms of 51 young volunteers covering the first four classes of Fitzpatrick's phototypes were acquired using a hyperspectral imaging system. The images were analyzed using a modified Beer–Lambert law that segregates the contribution of melanin from the other constituents to the skin absorption spectrum. The performance of the model was evaluated using the coefficient of determination (r-squared). The results revealed that the approach proposed in this study generated accurate melanin concentration distribution maps that allowed a correct classification of skin phototype. In conclusion, the proposed approach for assessing skin melanin concentration proved to be very reliable for classifying skin phototypes, and, as it provides maps that are easily read, it has the advantage of a possible extension of its applications to other research concerning skin pigmentation.     

Copper-mediated ATRP of methyl methacrylate in polar solvents using a bifunctional pyridinal diimine ligand

The bifunctional pyridinal diimine ligand, bis(2-pyridinal)ethylenediimine, was employed in copper-mediated ATRP of methylmethacrylate using solvents such as acetonitrile, N,N-dimethyl formamide and dimethylsulfoxide. Solvent polarity was found to play a crucial role in determining the extent of control in the ATRP process. Acetonitrile showed the best control when used at a level of 33 vol.-%.