Molecular orientation and structure in one-layer Langmuir−Blodgett (LB) films of octadecyldimethylamine oxide (C18DAO) and dioctadecyldimethylammonium chloride (2C18DAC) were investigated by use of infrared (IR) transmission, reflection−absorption (RA), and attenuated total reflectance (ATR) spectroscopy. The IR measurements suggest that the alkyl chains of the one-layer LB film of 2C18DAC on a gold-evaporated glass slide are highly ordered, whereas those of the C18DAO LB film have some gauche conformers. The molecular orientation and structure in both LB films show significant substrate dependence. Probably, the headgroup−substrate interaction controls them. Aging effects on the LB and Langmuir (L) films on an air−substrate interface were studied for the two kinds of amphiphiles. The alkyl chains of C18DAO in the LB film on the gold-evaporated glass slide become more ordered with time whereas the reverse trend is observed for those of 2C18DAC in the film. The effects on the L films were investigated by measuring IR spectra of the LB films prepared from the L films at various stages. The alkyl chains are less ordered in the LB films of C18DAO and 2C18DAC prepared from the aged L films. It is also noted that the molecular orientation and structure in the films of both compounds show strong pH dependence, presumably because of the strong interaction between the headgroups and substrates.

Abstract. The present study demonstrates that Raman spectroscopy is a powerful tool for the detection of virusinfected cells. Adenovirus infection of human embryonic kidney 293 cells was successfully detected at 12, 24, and 48 h after initiating the infection. The score plot of principal component analysis discriminated the spectra of the infected cells from those of the control cells. The viral infection was confirmed by the conventional immunostaining method performed 24 h after the infection. The newly developed method provides a fast and label-free means for the detection of virus-infected cells.

Infrared (IR) reflection−absorption (RA) spectra have been measured for one- and five-monolayer Langmuir−Blodgett (LB) films of octadecyldimethylamine oxide (C18DAO) and dioctadecyldimethylammonium chloride (2C18DAC) on gold- and silver-evaporated glass slides over a temperature range of 25−110 °C. Dependences of the thermal behavior of the LB films of C18DAO and 2C18DAC upon the substrates and the number of layers have been discussed. The LB films of C18DAO on the gold-evaporated glass slides are more thermally stable than those on the silver-evaporated glass slides. The interaction between the headgroup and the substrate may be stronger for the former than the latter, providing the films with the higher thermal stability. The one-monolayer LB film of C18DAO on the gold-evaporated glass slide shows a clear order−disorder transition around 70 °C. In contrast, the corresponding five-monolayer LB film gives a sharp transition at about 45 °C and a rather broad one around 80 °C. It seems that the accumulation of the upper layers yields independent transitions for the first layer and the rest of the layers and lowers the thermal stability of the first layer. The thermal behavior of the LB films of 2C18DAC and C18DAO is clearly different. For example, the 2C18DAC films show partial recovery after the annealing from 110 °C, but the C18DAO films undergo irreversible temperature-dependent changes. Probably, the difference in the thermal behavior results from the different nature of the substrate−headgroup interaction between them.

The thermal property of octadecyldimethylamine oxide (C 18 DAO) multilayer Langmuir-Blodgett (LB) film was investigated by infrared reflection-absorption (IRRA) spectrometry and two techniques of molecular orientation analysis. A conventional estimation theory of molecular orientation is expanded in the present study so that the first layer of the LB film that shows thermal properties significantly different from other layers is discussed separately. The results by the conventional analytical technique suggest that the multilayer LB film is thermally disordered at 50 °C and melts at 60 °C. The new technique, on the other hand, suggests that only the first layer of the LB film is greatly disordered between 50 and 60 °C, prior to the entire melting above 60 °C. The newly proposed technique gives insight into the structure of a LB film that is not uniform in structure that depends on thickness. The differing of thermal properties of the first and the rest of the layers revealed by the new method suggests that the headgroup of C 18 DAO has a uniquely strong interaction potential with the gold surface, probably due to its strong dipole.

One- and multilayer Langmuir−Blodgett (LB) films of octadecyldimethylamine oxide (C18DAO) and dioctadecyldimethylammonium chloride (2C18DAC) were prepared on gold- and silver-evaporated glass slides. The first and the rest of the layers were deposited by vertical dipping and horizontal lifting methods, respectively. Infrared (IR) reflection−absorption (RA) spectra were measured for the LB films to investigate the dependence of molecular orientation and structure on the number of layers and the substrates. X-ray diffraction and wetting properties were also measured for some of the films. For both C18DAO and 2C18DAC, there are remarkable changes in the 3000−2800 and 1700−1200 cm-1 regions between spectra of the one-monolayer LB films and those of the two-monolayer LB films irrespective of the substrates. In the spectra of the LB films of C18DAO on gold-evaporated glass slides, bands due to CH2 stretching modes show a downward shift by 5−7 cm-1 and their intensities become much weaker upon the deposition of the second layer on the first layer, suggesting that the hydrocarbon chain becomes ordered and perpendicular to the substrate surface. In general, the rearrangement of the molecular assemblies takes place during the accumulation of the upper layers in the multilayer LB films of C18DAO and 2C18DAC on the gold-evaporated glass slides.

A special place among vegetable oils was occupied by natural tobacco oil. Natural tobacco oil in folk medicine is used as an antiseptic and antibacterial agent. To determine the possible alternative use of tobacco, the seeds representing Kazakhstan tobacco cultivars, extracted from ground Nicotiana tabacum seeds, were investigated by using the cold press. The quality of the oil was assessed in terms of free fatty acid content. The percentage oil yield was 36.75 ± 0.50%. Tobacco seed oil is highly unsaturated, nonacidic, and would require little purification. The oil can be used for the production of soap, antiwrinkle cream for the face, hair shampoo, shoe cream, and as a high-resolution base oil for perfumes and light industry and can be commercialized due to its high oil yield, for use as anti-inflammatory drugs.

No abstract

This is an open access journal, and articles are distributed under the terms of the Creative Commons Attribution-Non Commercial-ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms.