Maternal diabetes develops in 2-6% of total pregnancies, depending on geographical and ethnic background. About 10% of fetuses from diabetic pregnancy display congenital malformations in various organ systems including cardiovascular, gastrointestinal, genitourinary and neurological systems, among which the neural tube defects (NTDs) such as anencephaly, holoprosencephaly and syntelencephaly were more frequently demonstrated. Recent studies by the Diabetes Control and Complications Trial Research Group show that tight glycemic control early in pregnancy decreases the progression of a number of diabetic complications. However, it appears that the pre-existing tissue damage cannot be reversed even after normoglycemic levels are achieved during pregnancy. In recent years, considerable efforts have been made to investigate the etiology of birth defects among infants of diabetic mothers. It has been shown that diabetes-induced fetal abnormalities are accompanied by some metabolic disturbances including elevated superoxide dismutase (SOD) activity, reduced levels of myoinositol and arachidonic acid and inhibition of the pentose phosphate shunt pathway. Moreover, the frequency of fetal malformations in diabetic pregnancy has been reported to be markedly reduced by dietary supplements of antioxidants such as vitamin E, vitamin C and butylated hy- droxytoluene, suggesting that oxidative stress is involved in the etiology of fetal dysmorphogenesis. Furthermore, several experimental studies have shown that NTDs in embryos of diabetic mice are associated with altered expression of genes, which control development of the neural tube. In this review, recent findings of possible molecular mechanisms which cause morphological changes during neural tube development in embryos of diabetic pregnancy are discussed.

Spray pyrolyzed ZnO films prepared using solution containing ethanol and water (volume ratio 1:1), exhibited optical transmission of 85% in the visible range and electrical resistivity of 78Ωcm. These samples were irradiated using 120MeV Au ion beam and then characterized using optical absorption and transmission, x-ray diffraction (XRD), electrical resistivity measurements, x-ray photoelectron spectroscopy (XPS), and photoluminescence studies. It appears that irradiation does not affect absorption edge while optical transmittance was slightly reduced. But intensities of peaks of XRD and photoluminescence were found to decrease continuously with increasing ion fluence. Electrical resistivity of the films decreased considerably (from 78to0.71Ωcm) with increase in ion fluence. Atomic concentration from XPS analysis showed that Zn∕O ratio is getting increased due to ion beam irradiation. Variations in carrier concentration were also measured using Hall measurements.

Thermally deposited 200 nm polycrystalline films of lithium fluoride (LiF) grown on glass substrates were irradiated with 150 MeV Ag ions at various fluences between 1 × 1011 and 2 × 1013 ions cm−2. The irradiation induced structural and optical modifications were studied using glancing angle x-ray diffraction (GAXRD), optical absorption and photoluminescence (PL) spectroscopy. The GAXRD results show that the films are polycrystalline and the average grain size (estimated from the widths of the GAXRD peak using the Scherrer formula) decreases systematically from 46.3 nm for the pristine sample to 18.3 nm for the sample irradiated at a fluence of 3 × 1012 ions cm−2. Thereafter, it remains constant. This reduction is attributed to strain induced fragmentation of grains. The optical absorption studies show dominant absorption bands of F3 (385 nm) and F2 (445 nm) colour centres. It is observed that the concentration of the colour centres increases with ion fluence and gets saturated at higher fluences. This can be correlated with GAXRD results in the sense that as the density of grain boundaries increases the concentration of colour centres also increases. The variation with fluence in PL intensities of the F2 and colour centres is studied. The intensity of both bands (F2 and ) increases up to a fluence of 1 × 1012 ions cm−2, followed by an exponential decrease, which is due to the increase in the non-radiative transition rate in the presence of defect-rich material.

In this work, swift heavy ion (SHI) induced surface smoothing, roughening and sputtering of thermally immiscible Fe/Bi bilayer system has been investigated. The pristine and irradiated samples were analysed by Rutherford backscattering spectrometry (RBS), grazing angle x-ray diffraction (XRD), atomic force microscopy and scanning electron microscopy including x-ray dispersive energy analyzer. RBS analysis revealed that steepness of the low energy edge of the Bi signal increases at a fluence of 3 × 1013 ions cm−2, beyond which the slope of the rear edge decreases. The increased steepness is due to smoothing induced at initial fluence; however, the decrease in the slope of rear edge beyond 3 × 1013 ions cm−2 fluence is a result of surface roughening. XRD reveals the increase in the crystalline nature of Bi after irradiation at 3 × 1013 ions cm−2. Irradiation at higher fluences from 6 × 1013 to 1 × 1014 ions cm−2 leads to a decrease in the crystalline nature of Bi. Surface roughness of pristine and irradiated samples from AFM analysis revealed that initially roughness decreases with a fluence of 3 × 1013 ions cm−2. However, at higher fluences, beyond 3 × 1013 ions cm−2, the agglomeration of smaller grains has been observed due to the shear flow mechanism, which results in surface roughening. The observed behaviour of surface smoothing and roughening under SHI irradiation may be explained on the basis of the thermal spike model.

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