Structural and optical characterization of alpha-irradiated and chemically etched PM-355 solid state nuclear track detectors before and after solar exposure

PM-355 polymeric solid state nuclear track detectors were studied. Samples were irradiated with alpha particles before and after exposure to sunlight under various seasonal conditions. Track formation and optical characteristics of chemically etched samples were investigated. X-ray diffraction (XRD) analysis showed that the dominant structure of the PM-355 detectors is of an amorphous nature with some degree of crystallinity. Micro strain, distortion density and distortion parameter were calculated from the XRD data, and indicate that the structure was modified after alpha irradiation and solar exposure. There was a tendency in the structure towards crystallinity. Some optical properties of PM-355 detectors were studied using Ultraviolet-Visible absorption spectroscopy. The absorption edge was detectable in all samples. The direct band gap decreased first and then subsequently increased again. The fluorescence spectra of alpha irradiated and solar exposed PM-355 polymer detectors after chemical etching showed three dominant peaks at wavelengths 327, 418 and 465 nm, respectively. The changes in the optical properties can be used to detect the effect of alpha and ultraviolet irradiations. The variation of the optical band gap, fluorescence spectra and/or track diameters can be used as a detection of nuclear radiation.

What drives intentional overdose with non-prescription drugs? A cross-sectional study

BACKGROUND

Use of overdosage of Non-Prescription Drugs (NPD) among university students is a serious public health issue. However, there are no extensive studies that measured the prevalence of taking more than the recommended dose of NPD and/or identified the risk associated with this behavior among university students.

OBJECTIVES

This study was undertaken to assess the prevalence and associated risks of self-overdosage with NPDs in university students in United Arab Emirates (UAE).

METHODS

A cross-sectional survey-based study was conducted from January to April 2014, among 2875 students in three randomly selected universities. A structured and validated questionnaire was used to collect the responses of the students. SPSS version 20 was used to analyze the data.

RESULTS

Out of 2875 students, only 2355 surveys were fully answered, returned back and included in the present study. Of 2355, more than half (1348; 57.2%) the participants reported using Oral NPD (ONPD) in the past 90 days before conducting the study and were asked to complete the survey. Only 290 (22%) of a total 1348 participants reported taking more than the recommended dose of ONPD in the previous three months before conducting the study. Analgesic/antipyretic (223, 16.5%) and anti-allergic (67, 4.9%) drugs were more than other classes of the ONPD, reported to be taken in a dose, more than the recommended dosage. The most common justifications for taking more than the recommended dose of ONPD among respondents were severe symptoms (6%), the belief that the recommended dose would not be sufficient to relieve the symptom (5%), the belief that a stronger dose would relieve the symptoms faster (11%), and previous experience (4%). Our results identified three risk factors for taking more than the recommended dose of NPD. High frequently drug-users of daily use (OR=3.494, 95% CI: 1.677-7.279) (P<0.001), and students from non-medical colleges had higher odds of taking more than the recommended dosage as compared to students from medical colleges (OR=1.486, 95% CI: 1.060-2.085, P-value<0.05). Furthermore\re, participants with a poly-pharmacy behavior had higher odds of taking overdosage of ONPD than single NPD users (OR=1.918, 95% CI: 1.440-2.555) (P<0.001).

CONCLUSION

There are a sizable proportion of university students that use overdosage of NPD, but it is more serious issue when it comes to non-medical student. There is a need for educational programs designed to increase awareness among all university students and to motivate them not to use overdosage of NPD. Further studies are also required to investigate additional explanatory variables that could influence the practice of overdosage with NPD.

Pulsed UV laser-induced modifications in optical and structural characteristics of alpha-irradiated PM-355 SSNTD

Pre- and postalpha-exposed PM-355 detectors were irradiated using UV laser with different number of pulses (100, 150, 200, 300, and 400). UV laser beam energy of 20mJ per pulse with a pulse width of 9ns was incident on an area of 19.6mm² of the samples. XRD spectra indicated that for both reference and UV-irradiated samples, the structure is amorphous, but the crystallite size increases upon UV irradiation. The same results were obtained from SEM analysis. Optical properties of PM-355 polymeric solid-state nuclear track detectors were also investigated. Absorbance measurements for all PM-355 samples in the range of 200-400nm showed that the absorption edge had a blue shift up to a certain value, and then, it had an oscillating behavior. Photoluminescence spectra of PM-355 at 250nm revealed a decrease in the broadband peak intensity as a function of the number of UV pulses, while the wavelengths corresponding to the peaks had random shifts.

Localization of peripheral dopamine D1 and D2 receptors in rat corpus cavernosum

OBJECTIVE

To detect and locate anatomically peripheral dopamine D1 and D2 receptors in rat cavernosa, as dopamine is important in sexual drive and penile erection through receptors located in the central nervous system.

MATERIALS AND METHODS

Corpora cavernosa were obtained from Sprague-Dawley rats; total RNA and membrane proteins were extracted and cryostat sections prepared. The rat brain hypothalamus was used as a control for dopamine D1 and D2 receptors. The presence and expression of peripheral dopamine D1 and D2 receptor mRNAs in rat corpus cavernosa was assessed using reverse transcription and polymerase chain reaction (RT-PCR), and Northern blot hybridization using (32)P-UTP-labelled RNA probes. Concurrently, corresponding proteins from D1 and D2 receptors were assayed and detected by a Western blotting technique. The anatomical location of dopamine D1 and D2 receptor mRNAs in rat penile tissues was identified by in situ hybridization using (35)S-UTP-labelled RNA probes in cryostat sections. Immunohistochemical staining was used to locate peripheral dopamine D1 and D2 receptor proteins in rat corpora cavernosa.

RESULTS

Dopamine D1 and D2 receptor gene expression was detected in rat corpora cavernosa. In situ hybridization signals for dopamine D1 and D2 receptor mRNAs were localized to corpus cavernosal tissues and dorsal vessels in the rat penis. Western blot analyses showed peripheral dopamine D1 and D2 receptor proteins in rat corpora cavernosa. Immunohistochemically, peripheral dopamine D1 and D2 receptor proteins were detected in dorsal nerves, dorsal vessels and corpus cavernosal smooth muscle of the rat penile tissues.

CONCLUSIONS

Peripheral dopamine D1 and D2 receptors are present in the corpora cavernosa of rats. The functional significance of these receptors and signal transduction pathways in modulating the vascular tone of the penis warrants further investigation.