Several synthetic techniques for metal-free phthalocyanines (Pc) and d-and f-metal phthalocyaninates (''PcM'') starting from different precursors (phthalonitrile, urea and phthalic anhydride, phthalimide, phthalic acid, etc.) are reviewed. Conventional methods are presented, as well as some less well-known techniques such as those using ultrasound, laser, microwaves, or nuclear transformation. Special attention is paid to phthalocyanine formation at relatively low temperatures (0-60 1C). Experimental results on Pc formation using UV-irradiation of the reaction system are presented.

No abstract

This work describes the production of silicon carbide using microwaves as the energy source, which was supplied by means of variable power, up to 2000 Watts, magnetron operating at 2.45 GHz. The obtained samples were analyzed by means of X-ray diffraction and observed with electron microscopy (SEM). Temperatures achieved were around 2000 degrees C, which is the upper limit for the beta-SiC growth regime, before getting other SiC polytypes. Analysis of different portions of the sample showed that beta-SiC was the only formed compound, although free SiO2 and graphite were also present. Observations made by SEM demonstrated different crystal growth regime, meaning that thermal conditions were not totally uniform. The amount of beta-SiC found and the relative simplicity of the device prove that production of this material from silica and graphite is possible by applying microwaves as an energy source.

One of the biggest health problems facing underdeveloped countries is the lack of medical attention to the entire population; usually, the person is treated once he is sick and/or when it is already an emergency. Having a method of health prevention, which allows obtaining information on the health status of the person in general, will help the health sector to prevent diseases. There are several diseases that alter the chemical variables found in the skin, such as dehydration, 1 that is why it is important to carry out studies that help quantify skin parameters. The skin is the largest organ of the human body, acts as a protective barrier that isolates the organism from the environment that surrounds it, protecting it, and helping to maintain its structures intact, while acting as a communication system with the environment, 2 which is why it could be an excellent indicator of diseases. When the light comes into contact with the skin, different optical phenomena such as reflection, absorption, scattering, etc are presented. These phenomena occur due to the structure and composition of the skin since it contains molecules that have the capacity to absorb light of different wavelengths.

No abstract