In Vitro Efficacy of Cyclosporine A and Various Antiseptics and Antiviral Drugs on Adenovirus Genotype 8, a Common Cause of Epidemic Keratoconjunctivitis

Purpose: To evaluate the in vitro efficacy of cidofovir, ganciclovir, povidone iodine, chlorhexidine, and cyclosporine A on adenovirus genotype 8 Methods: Conjunctival samples were collected from patients with adenoviral conjunctivitis and cultured in A549 cells. Adenovirus diagnosis was confirmed by RT-PCR. For each drug, the 50% cytotoxic concentration (CC₅₀) was determined. Subsequently, the antiviral activity was tested at concentrations below CC₅₀, and the 50% inhibitor concentration (IC₅₀) of drugs was determined.Results: While the IC₅₀ of cidofovir against adenovirus genotype 8 was 3.07 ± 0.8 µM, ganciclovir, povidone iodine, chlorhexidine, and cyclosporine A were not found to be effective against adenovirus genotype 8 at concentrations below the CC₅₀ value.Conclusions: Cidofovir was found effective and the IC₅₀ value was within the ranges in the literature. Ganciclovir and cyclosporine A were found to be ineffective at doses below the cytotoxic dose, povidone iodine and chlorhexidine were found to be highly cytotoxic.

Predicting the Effects of Carbapenem/Carbapenemase Inhibitor Combinations against KPC-Producing Klebsiella pneumoniae in Time-Kill Experiments: Alternative versus Traditional Approaches to MIC Determination

Traditionally, the antibacterial activity of β-lactam antibiotics in the presence of β-lactamase inhibitors is determined at the fixed inhibitor concentration. This traditional approach does not consider the ratio of antibiotic-to-inhibitor concentrations achieved in humans. To explore whether an alternative pharmacokinetically based approach to estimate MICs in combinations is predictive of antimicrobial efficacy, the effects of imipenem and doripenem alone and in combination with relebactam were studied in time-kill experiments against carbapenemase-producing Klebsiella pneumoniae. The carbapenem-to-relebactam concentration ratios in time-kill assays were equal to the therapeutic 24-h area under the concentration-time curve (AUC) ratios of the drugs (1.5/1). The simulated levels of carbapenem and relebactam were equal to their concentrations achieved in humans. When effects of combined regimens were plotted against respective C/MICs, a sigmoid relationship was obtained only with MICs determined by pharmacokinetically based method. The effectiveness of both carbapenems in the presence of relebactam was comparable by the results of time-kill experiments. These findings suggest that (1) antibiotic/inhibitor MICs determined at a pharmacokinetically based concentration ratio allow an adequate assessment of carbapenem susceptibility in carbapenemase-producing K. pneumoniae strains and can be used to predict antibacterial effects; (2) in time-kill experiments, the effects of imipenem and doripenem in the presence of relebactam are comparable.

NEW CORROSION INHIBITORS BASED ON AMINES AND AMIDES

In this work, new inhibitors of metal corrosion in sulfuric acid media are investigated depending on the duration of the process, inhibitor concentration and temperature. The main parameters of the synthesis of new corrosion inhibitors for metals of grade St.3 and St.12 with the use of amine and amide-containing organic substances have been determined, and methods for preparing these inhibitors have been described. The physicochemical properties of amine and amide containing organic inhibitors of corrosion and salt deposition in acidic process media have been studied.

Corrosion inhibition and statistical data of low carbon steel in HCl media by admixed organic compounds

Corrosion inhibition of carbon steels with organic compounds exhibiting effective corrosion inhibition is an on-going research. The corrosion inhibition of low carbon steel in 1M HCl solution by the combined admixture of vanillin and benzonitrile (VBN), and salvia officinalis with lavendulan officinalis (SLV) was studied by weight loss method. Results obtained show that VBN and SLV performed effectively with maximum inhibition efficiency 91.03% at 1.5% VBN concentration and 97.89% at 5% SLV concentration. The inhibition efficiency of VBN increased with concentration but decreased with exposure time compared to the values obtained for SLV which showed non-dependence on concentration and exposure time after 1% SLV concentration. Correlation plots of inhibition efficiency versus inhibitor concentration show VBN to be more concentration dependent in performance. Calculated data for standard deviation shows the degree of variation from mean values for both compounds is significant at low inhibitor concentration due to time dependence action. Statistical analysis through ANOVA shows inhibitor concentration overwhelmingly influences the inhibition performance of the despite even though exposure time is statistically relevant to minimal degree.

Inhibition of Mild Steel Corrosion by 4-benzyl-1-(4-oxo-4-phenylbutanoyl)thiosemicarbazide: Gravimetrical, Adsorption and Theoretical Studies

Gravimetric measurements were applied to study the inhibitory effect of 4-benzyl-1-(4-oxo-4-phenylbutanoyl)thiosemicarbazide (BOT) on the corrosion of mild steel in 1.0 M HCl. BOT has a good inhibitory efficacy of 92.5 percent at 500 ppm, according to weight loss results. The effect of inhibitor concentration on the mild corrosion behavior of steel was investigated and it was discovered that the higher the inhibitor concentration, the higher the damping efficiency. The results confirm that BOT is an effective corrosion inhibitor for mild steel in the presence of 1.0 M HCl. Furthermore, the higher protection efficiency with increasing temperature and the free energy value showed that BOT molecules participate in both chemisorption (coordination bonds between the active sites of BOT molecules and d-orbital of iron atoms) and physisorption (through the physical interactions on the mild steel surface). The adsorption mechanism on the mild steel surface obeys the Langmuir adsorption isotherm model. Quantum chemical calculations based on the DFT calculations were conducted on BOT. DFT calculations indicated that the protective efficacy of the tested inhibitor increased with the increase in energy of HOMO. The theoretical findings revealed that the broadly stretched linked functional groups (carbonyl and thionyl) and heteroatoms (sulfur, nitrogen and oxygen) in the structure of tested inhibitor molecules are responsible for the significant inhibitive performance, due to possible bonding with Fe atoms on the mild steel surface by donating electrons to the d-orbitals of Fe atoms. Both experimental and theoretical findings in the current investigation are in excellent harmony.

Experimental study and mathematical modelling of the corrosi-on inhibition of mild steel with an organic compound in 1 M HCl

In this paper, synthesized organic compound of the family of ketene dithioacetal was studied as corrosion inhibitors for mild steel in 1.0 M hydrochloric acid by gravimetric measurement. The aim of this work is to study the effect of inhibitor concentration and the temperature on the resistance, corrosion and to compare the experimental results with mathematical models. The structural properties were performed using scanning electron microscopy technique. It has been found that the inhibition efficiency, increases with increasing inhibitor concentration. The adsorption of studied compounds on mild steel surface follows Langmuir’s isotherm. Obtained data were analyzed by suggesting two mathematical models based on linear and quadratic regression, taking into account the influence of concentration and temperature on the inhibition efficiency. Obtained experimental data were in good agreement with those predicated by the quadratic model

Study of Corrosion Behavior of N’-(2-(2-oxomethylpyrrol-1-yl)ethyl)piperidine for Mild Steel in the Acid Environment

The corrosion inhibition of mild steel in 1 M hydrochloric acid solution by N'-(2-(2-oxomethylpyrrol-1-yl)ethyl)piperidine (N-OPEP) was studied employing weight loss techniques. The experimental findings revealed that N-OPEP is the most excellent corrosion inhibitor, and the inhibitory performance increases with an increase in the inhibitor concentration. Furthermore, the inhibition efficiency decreases with an increase in the solution Temperature. The adsorption of inhibitor molecules on a mild steel surface followed Langmuir’s isotherm model and was found to be spontaneous. Scanning electron microscopy (SEM) photographs approved the formation of a protective layer of the inhibitor molecules on the surface of mild steel.

Paraformaldehyde as a corrosion inhibitor for carbon steel in (%15) HCl

The effect of paraformaldehyde in the solution of 15% HCL as an inhibitor of C-steel corrosion has been studied using the weight loss method. It was found that the efficiency of inhibitor increased by increasing the inhibitor concentration and decreasing temperatures. Also, the action of paraformaldehyde as a corrosion inhibitor has been attributed to the insoluble complexes was adsorbed on the C-steel surface. The iron complexes were identified by FTIR spectrum and the mechanism of inhibition was explained as Langmuir adsorption. The thermodynamic parameters of the adsorption process were calculated and explained.

Synthesis New Pyridinium Salts as Corrosion Inhibitors for Mild Steel in 1 M H2SO4

Some new pyridinium salts, namely 4-(4-Chloro-benzylidene-hydrazinocarbonyl)-1-phenyl-pyridinium bromide, C1; 4-(4-Chloro-benzylidene-hydrazinocarbonyl)-1-butyl-pyridinium bromide, C2; 4-(4-Chloro-benzylidene-hydrazinocarbonyl)-1-phencyl-pyridinium bromide, C3; were synthesized and Corrosion inhibitors for mild steel were tested in a 1M H2SO4aqueous solution at 20ºC for 24 hours using weight loss measurements. The findings revealed that the inhibition efficiency of all pyridinium bromide derivatives converges at the maximum concentration. An increase in inhibitor concentration is associated with a decrease in corrosion rate, an increase in inhibition efficiencies, and an increase in surface degree of coverage. The physisorption effects for (C1, C2, and C3) were revealed by the free energy values of adsorption, which provided useful information for predicting the interaction between the metal surface and organic molecules as corrosion inhibitors.