INVESTIGATION OF DIPENTENE ISOLATION POSSIBILITY FROM TIRES PYROLYSIS OIL IN LEAD MELT

The work is aimed at experimental substantiation of dipentene (dl-limonene) extraction from pyrolysis liquid obtained by pyrolysis in the lead melt of tires of different brands. Pyrolysis liquid was isolated under conditions that reduce the sulfur content and increase the proportion of dipentene in the direct-contact reactor in the lead melt and in the temperature range of 400-470 °C. A method for extracting dipentene from pyrolytic liquid by distillation at normal pressure, in vacuum, and two-stage distillation (first with water vapor, then vacuum distillation) to obtain fractions enriched with dipentene was tested. The results obtained demonstrate that at this stage of the study the chemically unstable fraction of polyene hydrocarbons in the pyrolysis liquid is actively polymerized during distillation. The chromatographic analysis of the initial samples and distillation fractions was carried out, which showed that the feedstock contains more than 100 chemicals with a dipentene content of not more than 17%. Based on the evaluation of the obtained quantitative characteristics, distillation parameters providing the maximum yield of dipentene were determined. Under the proposed conditions, the enrichment of individual fractions with dipentene by ~4-6 times compared to its initial content in pyrolysis liquid was achieved. During distillation in vacuum, a fraction with a yield of 19.6% with a content of dipentene up to 40.8% was isolated, a narrow fraction with an yield of 4.8% with a maximum content of dipentene of 49.9% was isolated. During distillation with steam and subsequent vacuum distillation with a total yield of 17%, fractions with a dipentene content of 24-36 % were isolated. Further concentration of dipentene will obviously require more complex chemical synthesis and fractionation operations. The data obtained may be of interest in the development of a new process of pyrolysis of tires in the melt of heavy metals (lead), improving its efficiency by identifying economically important components for the production of commercial products.

Synthesis and structure determinantion of the first lead arsenide phosphide Pb2AsxP14–x (x ~ 3.7)

Pb2AsxP14–x was synthesized by reacting the pnicogens in a lead melt in sealed silica ampoules. A mixture of hydrogen peroxide and glacial acetic acid removed lead from the final product. Pb2AsxP14–x represents the first lead arsenide phosphide adopting a new structure type. Systematic substitution of phosphorus by arsenic leads to the formation of Pb2AsxP14–x with x ~ 3.7, a compound with a two-dimensional arrangement of polypnictide layers, coordinated by Pb2+ cations. Pb2AsxP14–x is structurally related to PbP7 where a three-dimensional polyphosphide network is realized instead. The structure of Pb2As3.7(1)P10.3(1) was determined from single crystal X-ray diffraction data: space group P212121 (no. 19), a = 10.060(1), b = 10.500(1), c = 13.711(2) Å, and V = 1448.3(4) Å3. The structure is discussed relative to PbP7 focusing on the differences in the polyanionic substructures of the two polypnictides.

Formulating propranolol as an amorphous melt affords reduced skin irritation potential for transdermal drug delivery

Oral propranolol is commonly the first-line treatment of infantile hemangioma. However, oral delivery of propranolol is limited by systemic side effects, particularly in infants. Topical application may be a more patient friendly alternative while concurrently affording targeted delivery to the site of the skin lesion. Unfortunately, dose-dependent skin irritation is typically observed when propranolol is applied topically. Of additional concern, irritation is often exacerbated by organic solvents required to formulate propranolol. To address these concerns, we present novel formulations of propranolol as amorphous melts. Propranolol melts were successfully synthesized, and their physicochemical properties were tuned suitably for transdermal delivery using dialkyl sulfosuccinates as the counter species. Melts used in this study possessed the ability to penetrate skin when applied neat, without the need of any addition of solvent. Moreover, skin irritation potential of the lead melt was reduced compared to that of the propranolol free base (PFB). This reduction may be due to association of propranolol with the counter species in amorphous melts. The results presented here suggest amorphous melt formulations may open up the possibility to topically deliver drugs that traditionally elicit skin irritation.

Application of Optimal Design Methodology on the Seismic Design of Piping Systems Supported by Elasto-Plastic Dampers

In this study, the optimal seismic design methodology which can consider the structural integrity of both the piping systems and the elasto-plastic supporting devices are developed. This methodology employs genetic algorithm and can search the optimal conditions such as the supporting location, the capacity and stiffness of the supporting devices. The lead extrusion damper is treated here as a typical elasto-plastic damper. Four kinds of evaluation functions; stress of piping systems, energy absorption, lead melt of dampers and energy absorbing balance are considered and each optimal condition is clarified and discussed. As the results, it is found that the optimal seismic design methodology proposed here is very effective and can be applied to the actual seismic designs for the piping systems supported by the elasto-plastic dampers, and can be also applied to the piping systems exposed to the actual earthquake waves which have various frequency components and the piping systems with a heavy local mass.