Photochemical Reaction of Nalidixic Acid in Methanol
The photochemical reactions of methanolic nalidixic acid (NAL) solution in the absence and in the presence of air have been investigated using 300 nm UV light. From the reactions, 1-ethyl-7-methyl-4-oxo-4-hydro-1,8naphthyridine (EMDN), formic acid, and formaldehyde are produced. In the presence of air, hydrogen peroxide is also detected along with the products listed above. The presence of oxygen during the irradiation of methanolic NAL solution effects on the product yield. The initial quantum yields of the products and of the NAL decomposition are determined. Possible reaction pathways for the photochemical reaction are suggested on the basis of the products analysis.
Effects of UV-, Visible-, Near-Infrared Beams in Three Therapy Resistance Case Studies of Fungal Skin Infections
Fungal and bacterial diseases, directly infecting various parts of body, have received much attention in recent years. Bacterial infections, such as Tinea Pedis, Pityriasis versicolor and Mycetoma can secondarily occur in superficial fungal damaged skin. They often occur in immune compromised individuals including diabetics and patients with peripheral arterial diseases. Mycetoma infections can travel through the bloodstream affecting different organs. In this paper, we investigate the photo-inactivation of the pathogens causing Tinea Pedis, Pityriasis versicolor, and Mycetoma infections in three therapy resistant patients without photosensitizing drugs. We have used a combination of visible to near-infrared (VIS/NIR) laser beams in association with blue (B), red (R) and ultra-violet (UV) light emitted diodes (LEDs) with incident doses of 0.63 - 21.43 J/cm 2 . These beams have minimum side effects on the normal part of the skin. According to the physicians’ assessments, all case study patients achieved an observable progress such as decreases in inflammatory lesions, rapid process of wound healing and scars improvements. Side effects such as inflammation, crusting, or hypopigmentation were not observed. The presented irradiation protocol may be a valuable complementary treatment for patients suffering from fungal and bacterial skin infections.
“ PARTIALLY-ACTIVATED ” FLUX RESIDUE IMPACTS ON ELECTRONIC ASSEMBLY RELIABILITIES
The reliabilities of the flux residue of electronic assemblies and semiconductor packages are attracting more and more attention with the adoption of no-clean fluxes by majority of the industry. In recent years, the concern of “partiallyactivated” flux residue and their influence on reliability have been significantly raised due to the miniaturization along with high density design trend, selective soldering process adoption, and the expanded use of pallets in wave soldering process. When flux residue becomes trapped under low stand-off devices, pallets or unsoldered areas (e.g. selective process), it may contain unevaporated solvent, “live” activators and metal complex intermediates with different chemical composition and concentration levels depending on the thermal profiles. These partially-activated residues can directly impact the corrosion, surface insulation and electrochemical migration of the final assembly. In this study, a few application tests were developed internally to understand this issue. Two traditional liquid flux and two newly developed fluxes were selected to build up the basic models. The preliminary results also provide a scientific approach to design highly reliable products with the goal to minimize the reliability risk for the complex PCB designs and assembly processes.