Synthesis, structure diversity, and antimicrobial studies of Ag(i) complexes with quinoline-type ligands

Compounds [Ag(5NO2Qu)2]BF4 (1) and [Ag(Qu3CN)(H2O)]BF4 (2) were prepared and studied from a structural perspective and screened for antimicrobial activity. The Ag(i) in the monomeric complex 1 is coordinated to two 5-nitroquinoline (5NO2Qu) ligands via the N-atoms of the quinoline rings with equidistant Ag-N bonds (2.146(2) \uc5) and a N-Ag-N# bond angle of 171.42(8)\ub0. The 2D coordination polymer 2 contains tetracoordinated Ag(i) with two N-atoms (N1 and N2#1) from two quinoline-3-carbonitrile (Qu3CN) ligands and two O-atoms (O1 and O1#1) from two water molecules. The Qu3CN ligand acts as a connector between the Ag(i) sites along the b-direction via two short Ag1-N1 (2.185(4) \uc5) and Ag1-N2#1 (2.204(4) \uc5) bonds. In addition, the Ag(i) is coordinated with two symmetry related water molecules which are also acting as connectors between the Ag(i) sites along the a-direction via two longer Ag1-O1 (2.470(4) \uc5) and Ag1-O1#2 (2.546(4) \uc5) bonds. Hirshfeld surface analysis confirmed the significance of the polar F⋯H contacts in the molecular packing of 1 (25.9%) and 2 (39.9%). In addition, the crystal packing of 1 showed a significant amount of polar O⋯H (23.5%) contacts. Also, both complexes displayed π-π stacking interactions. The Ag(i) complexes and the free ligand were assessed for their antimicrobial activities. It was found that 1 (MIC = 7.8 μg mL−1) and 2 (MIC = 31.25 μg mL−1) have higher antifungal potency against C. albicans than their free ligands (MIC = 125 μg mL−1). Interestingly, 1 has better antifungal activity than the standard nystatin (15.6 μg mL−1). Also, both Ag(i) complexes and the free ligands as well have better activity against P. mirabilis than the common antibiotic amoxicillin

Burden and risk factors for Pseudomonas aeruginosa community-acquired pneumonia:a Multinational Point Prevalence Study of Hospitalised Patients

Pseudornonas aeruginosa is a challenging bacterium to treat due to its intrinsic resistance to the antibiotics used most frequently in patients with community-acquired pneumonia (CAP). Data about the global burden and risk factors associated with P. aeruginosa-CAP are limited. We assessed the multinational burden and specific risk factors associated with P. aeruginosa-CAP. We enrolled 3193 patients in 54 countries with confirmed diagnosis of CAP who underwent microbiological testing at admission. Prevalence was calculated according to the identification of P. aeruginosa. Logistic regression analysis was used to identify risk factors for antibiotic-susceptible and antibiotic-resistant P. aeruginosa-CAP. The prevalence of P. aeruginosa and antibiotic-resistant P. aeruginosa-CAP was 4.2% and 2.0%, respectively. The rate of P. aeruginosa CAP in patients with prior infection/colonisation due to P. aeruginosa and at least one of the three independently associated chronic lung diseases (i.e. tracheostomy, bronchiectasis and/or very severe chronic obstructive pulmonary disease) was 67%. In contrast, the rate of P. aeruginosa-CAP was 2% in patients without prior P. aeruginosa infection/colonisation and none of the selected chronic lung diseases. The multinational prevalence of P. aeruginosa-CAP is low. The risk factors identified in this study may guide healthcare professionals in deciding empirical antibiotic coverage for CAP patients

Sorption of lead from aqueous solution by modified activated carbon prepared from olive stones

Environmental pollution, mainly in the aquatic systems, due to developments in industry, is one of the most significant problems of this century. Many industrial wastewater streams contain heavy metals, which are of great environmental concern and must be removed prior to water discharge or water recycling. The present study aims to develop a simple and rapid procedure for lead (II) removal. Laboratory-scale adsorption experiments were conducted aiming to remove lead from water samples. They were based on using powdered activated carbon (PACI), which was prepared from olive stones generated, as plant wastes, and modified with aqueous oxidizing agent such as (NH 4)2S2O8. The main parameters (pH, sorbent, lead concentrations, stirring times and temperature) influencing the sorption process in addition to the effect of some foreign ions were investigated. The results obtained indicated that the sorption of Pb2+ ions onto PACI is well described by the Langmuir, Freundlich and Dubinin- Radushkevich (D-R) adsorption models over the concentration range studied. Under the optimum experimental conditions employed, the removal of ca. 100% of Pb2+ ions was attained. The procedure was successfully applied to the removal of lead from aqueous and different natural water samples

Sorptive–Flotation of Copper(II) from Water Using Different Types of Powdered Activated Carbons as Sorbents and Oleic Acid as Surfactant

Different types of powdered activated carbon, viz. charcoal (PACh), graphite (PG) and three samples (PACI, PACII and PACIII) prepared from olive stones generated as plant wastes and modified with aqueous oxidizing agents, viz. H 2 O 2 , HNO 3 and (NH 4 ) 2 S 2 O 8 , were separated from aqueous solution by flotation using oleic acid (HOL) as a surfactant. The effects of initial temperature, initial pH of the suspension, initial carbon and surfactant concentrations, stirring times and the presence of foreign ions on the flotation efficiency of the carbon samples were investigated. Under optimum conditions, separation of the carbon samples was almost complete (~100%). The separation of Cu II -loaded carbon was also examined in the presence and absence of sulphide ions as activators. Nearly 100% Cu II was removed at pH 7 after stirring for 30 min or on raising the temperature of the solution to 30°C or higher. In addition, Cu II may be separated quantitatively at pH 3 and room temperature if sulphide ions are used as activators. The procedure was extended to the recovery of Cu II added to some natural water samples. On the basis of IR analyses and neutralization titrations of the surface groups, a mechanism for the sorption and flotation processes is advanced

Removal of Copper(II) from Aqueous Solutions by Flotation Using Limestone Fines as the Sorbent and Oleic Acid as the Surfactant

The removal of toxic copper(II) from aqueous solutions was investigated using limestone fines (LS), which are inexpensive and widespread over the globe, as the effective inorganic sorbent with oleic acid (HOL) as the surfactant. The main parameters (i.e. initial solution pH, sorbent, surfactant and copper concentrations, stirring times, temperature and presence of foreign ions) influencing the sorption and flotation processes were examined. The results obtained showed the removal of more than 98% Cu II at pH 7. It was also found that the addition of sodium and magnesium ions as activators enhanced the efficiency of copper separation. The procedure was successfully applied to recover copper spiked to some natural water samples. A mechanism for sorption and flotation is suggested

Removal of Copper(II) Ions from Aqueous Solutions. I. Adsorption Studies Using Powdered Marble Wastes as Sorbent

Batch adsorption experiments of copper(II) ions from aqueous solutions on to powdered marble wastes (PMW) have been performed. The latter is an effective inorganic sorbent which is inexpensive, widespread and may represent an environmental problem. The main parameters influencing the sorption process, i.e. initial solution pH, sorbent and Cu 2+ ion concentrations, stirring times and temperature, were examined. The results obtained revealed that the sorption of Cu 2+ ions on to PMW was endothermic in nature and followed first-order kinetics. Moreover, it was well described by the Langmuir, Freundlich and Dubinin–Radushkevich (D–R) adsorption models over the concentration range studied. Under the optimum experimental conditions employed, the removal of ca. 100% Cu 2+ ions was attained