Three new tetra-Schiff bases were synthesized and characterized to be used as photostabilizers for poly(vinyl chloride) (PVC) films. The photostability of PVC films (40 μm thickness) in the presence of Schiff bases (0.5 wt %) upon irradiation (300 h) with a UV light (λmax = 365 nm and light intensity = 6.43 × 10−9 ein∙dm−3∙s−1) was examined using various spectroscopic measurements and surface morphology analysis. The changes in various functional groups’ indices, weight and viscosity average molecular weight of PVC films were monitored against irradiation time. The additives used showed photostability for PVC films, with Schiff base 1 being the most effective additive upon irradiation, followed by 2 and 3. The atomic force microscopy (AFM) images for the PVC surface containing Schiff base 1 after irradiation were found to be smooth, with a roughness factor (Rq) of 36.8, compared to 132.2 for the PVC (blank). Several possible mechanisms that explain PVC photostabilization upon irradiation in the presence of tetra-Schiff bases were proposed.

Three phosphate esters 1-3 were successfully synthesized from the reaction of 2-, 3-and 4-hydroxybenzaldehyde with phosphoryl chloride. Reactions of 1-3 with benzidine in the presence of glacial acetic acid gave the corresponding novel phosphorus organic polymers 4-6 containing the azomethane linkage. The structures of the synthesized compounds were confirmed by Fourier transform infrared spectroscopy, nuclear magnetic resonance and elemental analysis. Interesting physiochemical properties for the polymeric materials 4-6 were observed using a combination of several techniques such as gel permeation chromatography, scanning electron microscopy, Brunauer-Emmett-Teller and nitrogen adsorption-desorption isotherm, Barrett-Joyner-Halenda and H-sorb 2600 analyzer. The mesoporous polymers 4-6 exhibit tunable porosity with Brunauer-Emmett-Teller surface area (SA BET = 24.8-30 m 2 ·g -1 ), pore volume (0.03-0.05 cm 3 ·g -1 ) and narrow pore size distribution, in which the average pore size was 2.4-2.8 nm. Polymers 4-6 were found to have high gas storage capacity and physico-chemical stability, particularly at a high pressure. At 323 K and 50 bars, polymers 4-6 have remarkable carbon dioxide uptake (up to 82.1 cm 3 ·g -1 ) and a low hydrogen uptake (up to 7.4 cm 3 ·g -1 ). The adsorption capacity of gasses for polymer 5 was found to be higher than those for polymers 4 and 6.

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Acne vulgaris is an extremely common condition affecting the pilosebaceous unit of the skin and characterized by presence of comedones, papules, pustules, nodules, cysts, which might result in permanent scars. Acne vulgaris commonly involve adolescents and young age groups. Active acne vulgaris is usually associated with several complications like hyper or hypopigmentation, scar formation and skin disfigurement. Previous studies have targeted the efficiency and safety of local and systemic agents in the treatment of active acne vulgaris. Superficial chemical peeling is a skin-wounding procedure which might cause some potentially undesirable adverse events. This study was conducted to review the efficacy and safety of superficial chemical peeling in the treatment of active acne vulgaris. It is a structured review of an earlier seven articles meeting the inclusion and exclusion criteria. The clinical assessments were based on pretreatment and post-treatment comparisons and the role of superficial chemical peeling in reduction of papules, pustules and comedones in active acne vulgaris. This study showed that almost all patients tolerated well the chemical peeling procedures despite a mild discomfort, burning, irritation and erythema have been reported; also the incidence of major adverse events was very low and easily manageable. In conclusion, chemical peeling with glycolic acid is a well-tolerated and safe treatment modality in active acne vulgaris while salicylic acid peels is a more convenient for treatment of darker skin patients and it showed significant and earlier improvement than glycolic acid

The influence of introducing benzothiazole and benzimidazole as a pending groups into the repeating unit of PVC has been studied on the bases of photostability measurements. The photostability of modified polymers were studied by monitoring the carbonyl Index (I CO ), polyene index (I po ) and hydroxyl index (I OH ), all results obtained indicated that PAA, PSS, PNN, PSA and PNA gave lower growth rate of I CO , I PO and I OH with irradiation time with respect to unmodified PVC film (control). The following trends of photostability are obtained PAA>PSS>PNN>PSA>PNA According to the experimental results several reaction mechanisms were proposed depending on the presence of benzothiazole and benzimidazole moieties in the polymer chain. The mode of chain scission was also investigated by measuring the variation of average viscosity molecular weight with irradiation time for modified PVC. The degree of deterioration (α) and the average number of chain scission (S) values were also calculated.