Chemical Analysis of Amoxicillin Samples Using Ultra Performance Liquid Chromatography in Tandem with Mass Spectrometry for the Distributed Pharmaceutical Analysis Laboratory

The global health crisis of “fake” drugs is rampant worldwide and causes 1 million deaths and $30 billion in damage annually, according to a recent report by the United States Pharmacopeia in 2021. Substandard and falsified medicines remain uncontrolled due to underreporting, poor detection methods, and a lack of cooperation between countries. To combat this, the University of Notre Dame and Chemists Without Borders established the Distributed Pharmaceutical Analysis Laboratory (DPAL) in 2014 to provide high quality, validated analysis of pharmaceutical samples from partners in the developing world. Heretofore, ultra-performance liquid chromatography in tandem with mass spectrometry (UPLC-MS) has not been utilized by DPAL institutions. This research presents an effective methodology for analyzing amoxicillin samples using UPLC-MS

Device physics of organic and perovskite solar cells

We report on fundamental electronic properties of the PTB7:PCBM70 bulk heterojunction solar cells: Sub-gap quantum efficiency measurements determine the Urbach energy of tail states (33 meV) and D/A interfacial bandgap (1.34 eV). Density of deep defects is determined by capacitance spectroscopy, and is ~1016 cm-3.eV-1. By photo-current spectroscopy, we assess surface recombination velocity at D/A interface, which translates to a capture cross-section of ~10-16 cm2 for deep defects. These properties are then used in our analytical modeling. Using a multiple-level trap model, we compute recombination rates in the cells. The model can predict dark saturation currents and ideality factors, and strongly suggests that band tail recombination is the main limiting factor of open-circuit voltage. Additionally, we find that, upon light exposure, photo-induced defects lead to increased trap-assisted recombination and photo-voltage instability. To increase photo-stability, we propose a novel n-i-p hybrid device where n+/a-Si:H is used as the front contact of the bulk heterojunction. Highly energetic photons (blue and UV light), which induce defects in the light-absorbing material, are blocked (absorbed) in the n+/a-Si:H layer. This leads to significant reduction of photo-induced damage in the blend, and thereby enhances photo-stability. Some photo-current is, however, lost due to absorption in n+/a-Si:H. In order to overcome this drawback, we present a novel organic-inorganic hybrid tandem solar cell, in which blue photons are harvested by an a-(SiC):H front cell. A PTB7:PCBM70 cell is used as the back cell. Our results demonstrate a VOC of 1.67 V, JSC of 7.3 mA/cm2 and overall efficiency of 7.6%, which is among the highest reported in the literature. In the last part of this dissertation, we study the electronic properties of methyl-ammonium lead iodide perovskite solar cells. Capacitance spectroscopy shows the existence of a shallow (0.24 eV) and a deep (~0.62 eV) defect band in the bandgap. Moreover, we find that attempt-to-escape frequency is ~1011 Hz. The deeper defect band has a Gaussian distribution with a peak density of ~3×1016 cm-3.eV-1. Ideality factors and dark saturation currents indicate that band-to-band recombination is dominant at high excitation levels, and limits the photo-voltage

Pattern of animal bites and factors associated with delay in post-exposure prophylaxis in bitten people

BACKGROUND: Since the epidemiology of animal bites and the relevant factors in post-exposure prophylaxis (PEP) are of great significance for preventing the deaths resulting from rabies and controlling the rabies disease, the main purpose of the current study is to account for the patterns of animal bites and factors associated with delay in PEP in bitten people.METHODS: This cross-sectional study was conducted on all animal bites cases in Khaf city, Khorasan Razavi province, Iran, and included 553 cases of animal bites recorded from March 2014 to February 2016 in the healthcare centers. Chi-square test (or Fisher’s exact test) was used to identify the factors associated with delays in PEP.RESULTS: Results indicated that majority of the cases with animal bites were men (79.7%) aged from 21 to 60 years (48.5%). Due to the type of animal bites in all ages, the damages caused by dogs (85.2%) were greater than the damages caused by cats (9%) and other domestic or wild animals (5.8%). The frequency of delay in treatment was 14.4% in women and 5.2% in men (P = 0.002). The frequency of treatment delay in housewives (18.6%) and children under 6 years old (6.3%) was greater than that in other occupations (P = 0.003).CONCLUSION: According to the current study's results, individuals’ gender and occupation are among the main factors associated with delay in PEP. Therefore, identifying factors related to delay in treatment and providing people with the necessary education by health personnel are of considerable significance in prevention of unpleasant consequences of animal bites

Estimating the mechanical anisotropy of the Iranian lithosphere using the wavelet coherence method

We calculated anisotropic wavelet coherence between Bouguer anomaly and topography in order to map the anisotropy of the effective elastic thickness of the Iranian lithosphere (Te). An orthotropic elastic plate model is used for inverting the anisotropic wavelet coherence to compute the mechanical anisotropy through the weak axis of the Te. Anisotropy of the Te-weak axis and the strength of the anisotropic parameter, namely the anisotropic coherence effect over the study area are estimated by restricting the rotated Morlet wavelet (fan wavelet) geometry over an azimuthal range of 90°. Large-scale Te variations have been shown to be associated with phenomena, such as mountain belts, subduction zones, craton boundaries, fault zones, and seismogenic regions. Although the correlation between the major tectonic features of the Iranian lithosphere and the distribution of the Te-weak axis is not general or precise, in some regions, such as the Central Iran Blocks, and the Alborz, Kopeh Dagh, Zagros, and Makran orogenic belts, the weak axis has a uniform or slowly varying pattern which changes over their boundaries. A perpendicular alignment between seismic anisotropy measurements in Iran and the Te-weak directions suggests a lithospheric origin for anisotropy. The correlation between averaged stress directions and the weak axis of the Te in Iran indicates that the present day stress field and the fossil strain are still related. Correlation between these factors suggests vertically coherent deformation of the lithosphere in Iran resulting from the multiply convergent orogenic processes. The complex mechanical anisotropy pattern of the Iranian lithosphere results from the interaction of many pre-existent structures which dominantly control the mechanical anisotropy of the lithosphere