In recent years the application of nano-porous templates, such as anodic alumina and PTFE, in the production of cylindrical nanostructures has been vast. In our work we used porous alumina membranes to produce luminescent nanowires from polystyrene and silica. The silica wires were fabricated by infiltration of a TEOS derived sol-gel into 200 nm diameter porous alumina membranes with vacuum assistance followed by annealing at 400 °C. Polystyrene luminescent, magnetic nanowires have been fabricated using a similar technique. The wires were studied by optical, confocal and transmission electron microscopy. Silica nanowires demonstrated a broad luminescence spectrum due to interstitial carbon defect emission. Polystyrene nanowires have demonstrated strong emission and interesting magnetic behaviour. Both polystyrene and silica maghemite loaded nanowires show alignment to an external magnetic field. We believe that these silica and polystyrene nanowires might find potential applications in photonics, bio-sensing and biological imaging.
The unambiguous identification and quantification of hazardous materials is of increasing importance in many sectors such as waste disposal, pharmaceutical manufacturing, and environmental protection. One particular problem in waste disposal and chemical manufacturing is the identification of solvents into chlorinated or non-chlorinated. In this work we have used Raman spectroscopy as the basis for a discrimination and quantification method for chlorinated solvents. Raman spectra of an extensive collection of solvent mixtures (200+) were collected using a JY-Horiba LabRam, infinity with a 488 nm excitation source. The solvent mixtures comprised of several chlorinated solvents: dichloromethane, chloroform, and 1,1,1-trichloroethane, mixed with solvents such as toluene, cyclohexane and/or acetone. The spectra were then analysed using a variety of chemometric techniques (Principal Component Analysis and Principal Component Regression) and machine learning (Neural Networks and Genetic Programming). In each case models were developed to identify the presence of chlorinated solvents in mixtures at levels of ~5%, to identify the type of chlorinated solvent and then to accurately quantify the amount of chlorinated solvent.
Raman spectroscopy was employed to spectroscopically fingerprint the range of animo acids, purines and pyramidines. Irradiation of these components by 10 Gray gamma rays shows that several of the amino acids and pyrimidines are particularly prone to molecular degradation. The spectroscopic signature of the degradation is utilized to identify the molecular origin of the degradation observed in the various biological macromolecules. Irradiation in solution compared to solid sate is employed in an effort to differentiate between primary and secondary ionization processes.
In this study Raman spectroscopy was employed distinguish between normal and abnormal human tissue. Raman spectra were obtained using a confocal Raman microspectrometer and a laser excitation of 514.532nm for a number of healthy tissues (Tonsil and Cervix) as well as for their diseased counterparts. Each tissue type was classified and its various spectral components were associated with vibrations, rotations etc. of the chemical bonds in the tissues' constituent components. Raman bands have been attributed to biological compounds such as proteins, lipids and DNA as well as to chemical bonds within these compounds such as, C=O stretch in Amide I (1645-1680 cm-1), NH bending in Amide III (1230-1310 cm-1), phenyl ring in Phenylalanine (1004 cm-1). Changes in the relative intensities, position, and width of these bands relate to the composition of the sample. Differences between healthy and diseased tissue with progression to malignancy have been identified and include; an increase in intensity of the phenylalanine ring breathing band (1004 cm-1), the C-C stretch of proteins (1082 cm-1), Amide I band (1655 cm-1) and the C-N stretching modes of proteins (1082cm-1). Decreases in relative intensities were also observed, and include a decrease in intensity of the CH2 deformation (1295 cm-1), CH2 bending of proteins and lipids (1445 cm-1), and the C=O stretching of proteins (1695 cm-1). The molecular origin of the observed spectral changes is discussed.
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