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Sulfate rocks, particularly gypsum rock as its most common near-surface form in the Earth's crust, are among the evaporitic rocks that due to their solubility can cause serious problems if they are present in the foundations and abutments of reservoir dams. To investigate the solubility of gypsum, gypsum blocks were taken from Gachsaran Formation outcrops located at a reservoir dam construction site in Iran. To perform the rock-dissolution experiments under pressure and water-flow conditions, a pneumatic–hydraulic pressure vessel with internal water circulation was designed and manufactured. Dissolution simulation experiments were performed at a constant temperature (25°C) and for a range of pressures, water-flow velocities and water acidities, the solution-rate constants for the experimental conditions considered. The results confirmed, first, that there are strong direct increasing relationships between pressure and the water-flow velocity with the solution-rate constant, while these relationships with increasing pH are reversed. Secondly, the values obtained from the rock-dissolution experiments under atmospheric conditions cannot be trusted as design parameters for dam foundation or abutments because the solution-rate constant values at the affected depth below reservoir dams can be several times higher than the surface value.

Introduction. There are limited data on human immunodeficiency viruses (HIV) infected people in the UAE and the Gulf region. This study aimed at assessing the prevalence and risk factors for potential clinically significant drug interactions (CSDIs) in a cohort of 181 HIV infected people in Dubai. Methods. A retrospective study was conducted at the outpatient infectious diseases clinic of Rashid hospital. Consecutive HIV seropositive people on anti-retroviral therapy (ART) were included. All potential CSDIs were analyzed and classified using Liverpool HIV drug interactions database. Results. Nucleoside reverse transcriptase inhibitors (NRTIs) and integrase strand transfer inhibitors (INSTIs) were the most frequently used antiretroviral agents (ARVs), while the most common (non-ARV) were cardiovascular medication followed by antilipidemic statins. A total of 140 potential CSDIs were found in nearly half (n=86, 47.5%) of the 181 included HIV persons. Of the 140 potential CSDIs, 27 (19%) were of weak clinical relevance, 108 (77%) were of potential clinical relevance, and 5 (4%) were of contraindicated clinical relevance interactions. Moreover, 52 (37.14%) of CSDIs were between two ARVs and 88 (62.85%) were between ARV and non-ARV drugs. In the univariate analysis, age, dyslipidemia, number of medications, analgesics use, statin use, supplement intake, time since diagnosis of HIV, number of ART, and use of a protease inhibitor (PI) were significant. In the logistic regression, factors independently associated with CSDIs were the number of medications (odds ratio [OR] 1.165, 95% CI 1.021-1.329, P = 0.023) and the time since diagnosis of HIV (OR 1.156, 95% CI 1.008-1.327, P = 0.038). Conclusion. The frequency of CSDIs between ART and co-medications is high in HIV seropositive people. Awareness of the risk factors may assist clinicians to recognize and manage CSDIs.

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