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Thiourea derivatives namely, phenylthiourea (PTU), N, N′-diphenylthiourea (DPTU) and N-naphtyl N′-phenylthiourea (NPTU) synthesised in our laboratory, were tested as inhibitors for the corrosion of cold rolled steel in 1 M HClO4 using polarisation and electrochemical impedance measurements. At 30 °C, PTU and DPTU stimulated corrosion at low concentrations while addition of NPTU caused inhibition at all concentrations. The best protection (93%) was obtained by adding NPTU at 2.5 × 10−4 M. Polarisation curves showed that NPTU acted as a mixed inhibitor. The degree of surface coverage of the adsorbed inhibitors was determined by the ac impedance technique. The adsorption of NPTU on the cold rolled steel surface obeyed the Langmuir adsorption isotherm. Corrosion behaviour in the presence of NPTU at various concentrations was studied in the temperature range 20–50 °C. Both the corrosion rate of cold rolled steel and protection efficiency increased with increasing temperature. Activation energies with and without NPTU were obtained from the temperature dependence of corrosion current. The thermodynamic functions of the adsorption processes were calculated from the polarisation data and were used to analyse the inhibitor adsorption mechanism. [ABSTRACT FROM AUTHOR]

Abstract: N-naphtyl N′-phenylthiourea (NPTU) synthesized in our laboratory, was tested as inhibitor for the corrosion of cold rolled steel in 1 M HClO4 by electrochemical measurements. Polarization curves show that NPTU acts as mixed type inhibitor. Changes in impedance parameters (charge transfer resistance, R t, and double layer capacitance, C dl) were indicative of adsorption of NPTU on the metal surface, leading to the formation of protective film. The degree of the surface coverage of the adsorbed inhibitors was determined by ac impedance technique, and it was found that the adsorption of this inhibitor on the cold rolled steel surface obeys the Langmuir adsorption isotherm. The effect of the temperature on the corrosion behavior with addition of 2.5×10−4 M of NPTU was studied in the temperature range 25–50 °C. Results show that the rate of corrosion of mild steel increased with increasing temperature both in the presence of inhibitor and in its absence. Activation energies and enthalpies of activation in the presence and absence of NPTU were obtained by measuring the temperature dependence of the corrosion current. The use of the transition state equation to calculate the apparent entropy of activation for dissolution of metals and alloys was criticized. [Copyright &y& Elsevier]

Abstract: The inhibition of the corrosion of carbon steel in 1M HClO4 by 2-mercapto-1-methylimidazole (MMI) has been investigated in relation to the concentration of the inhibitor as well as the temperature using weight loss and electrochemical measurements. The effect of the temperature on the corrosion behaviour with addition of different concentrations of MMI was studied in the temperature range 30–60°C. Polarization curves reveal that MMI is a mixed type inhibitor. The inhibition efficiency of MMI is temperature independent but increases with the inhibitor concentration. Changes in impedance parameters (charge transfer resistance, R t, and double-layer capacitance, C dl) were indicative of adsorption of MMI on the metal surface, leading to the formation of a protective film. Adsorption of MMI on the carbon steel surface is found to obey the Langmuir adsorption isotherm. Some thermodynamic functions of dissolution and adsorption processes were also determined. The X-ray photoelectron spectroscopy (XPS) of the carbon steel indicated that MMI is chemically adsorbed on the steel surface. Moreover, the electronic properties such as highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO) energy levels and molecular orbital densities were calculated. [Copyright &y& Elsevier]

Abstract: The inhibition of corrosion of copper in hydrochloric acid by 2-mercapto-1-methylimidazole was investigated by dc polarization, ac impedance and weight loss techniques. A significant decrease in the corrosion rate of copper was observed in the presence of the investigated compound. The corrosion rate was found to depend on the concentration of the inhibitor. The degree of surface coverage of the adsorbed inhibitor is determined by ac impedance technique, and it was found that the results obey the Langmuir adsorption isotherm. The potentiodynamic polarization data indicated that the inhibitor was of mixed type, but the anodic effect is more pronounced. The slopes of the cathodic and anodic Tafel lines are approximately constant and independent on the inhibitor concentration. This inhibitor lowered the corrosion reaction by blocking the copper surface through physical and chemical adsorption. The mechanism of inhibition was discussed in the light of the chemical structure of the undertaken inhibitor. Also, some thermodynamic data for the adsorption and dissolution processes are calculated and discussed. The reactivity of the compound under investigation was analyzed through Fukui indices, which are reactivity descriptors derived from density functional theory (DFT), to explain the great efficiency of this compound as corrosion inhibitor comparatively to other imidazole derivatives. [Copyright &y& Elsevier]

N, N′-Diphenylthiourea (DPTU) and N-naphthyl- N′-phenylthiourea (NPTU) synthesized in our laboratory, were tested as inhibitors for the corrosion of cold-rolled steel in 0.5 M H2SO4 by weight loss and electrochemical measurements. The studies clearly reveal that when we substitutes a phenyl group in N, N′-diphenylthiourea (DPTU) by naphthyl group to obtain N-naphthyl- N′-phenylthiourea (NPTU), the inhibition efficiency increases from 80 to 96% at 2 × 10−4 M. Polarization curves show that NPTU acts as mixed type inhibitor whereas DPTU predominates as cathodic inhibitor. Changes in impedance parameters (charge transfer resistance, R t, and double layer capacitance, C dl) were indicative of adsorption of DPTU and NPTU on the metal surface, leading to the formation of protective films. The degree of the surface coverage of the adsorbed inhibitors is determined by ac impedance technique, and it was found that the adsorption of these inhibitors on the cold-rolled steel surface obeys the Langmuir adsorption isotherm. The effect of the temperature on the corrosion behavior with addition of 10−4 M of DPTU and NPTU was studied in the temperature range 20–50 °C. Results show that the rate of corrosion of mild steel increased with increasing temperature both in the presence of inhibitors and in their absence. Activation energies in the presence and absence of DPTU and NPTU were obtained by measuring the temperature dependence of the corrosion current. The reactivity of these compounds was analyzed through theoretical calculations based on density functional theory to explain the different efficiency of these compounds as corrosion inhibitors. [ABSTRACT FROM AUTHOR]

Abstract: N-Phenyl oxalic dihydrazide (PODH) and oxalic N-phenylhydrazide N′-phenylthiosemicarbazide (OPHPT), synthesized in our laboratory, were tested as inhibitors for the corrosion of mild steel in molar HCl by electrochemical measurements. Inhibition efficiencies up to 92% for OPHPT and 79% for PODH can be obtained. Polarization curves reveal that PODH and OPHPT act as mixed type inhibitors. Adsorption of these inhibitors on the mild steel surface was found to obey the Langmuir adsorption isotherm. Results show that the rate of corrosion of mild steel increased with increasing temperature over the range 25–55°C both in the presence of inhibitors and in their absence. Activation energies in the presence and absence of PODH and OPHPT were obtained by measuring the temperature dependence of the corrosion current. The reactivity of these compounds was analyzed through theoretical calculations based on density functional theory to explain the different efficiency of these compounds as corrosion inhibitors. [Copyright &y& Elsevier]

The corrosion and inhibition behavior of mild steel in 1 M HCI in the presence of poly(4-vinylpyridine) (P4VP) and potassium iodide (KI) was investigated using weight loss measurements, potentiodynamic polarization studies and impedance measurements. The inhibition efficiency increased with increasing P4VP concentration. The inhibiting action of P4VP is considerably enhanced by the addition of potassium iodide. The adsorption of this compound either alone or in combination with iodide ions on the metal surface is found to obey Lamgmir's adsorption isotherm. The experimental results suggest that the presence of iodide ions in the solution increases the surface coverage U and, therefore, indicate the joint adsorption of P4VP and iodide ions. On the other hand, it was found that the inhibiting effect of P4VP and (P4VP + KI) increased with increasing temperature of the corrosion medium. The presence of these species in the solution decreases the double layer capacitance and increases the charge transfer resistance, both derived from Nyquist plots obtained from a.c. impedance studies. The variation of charge transfer resistance with time suggests that the inhibitive action of (P4VP + KI) depends mainly on the protective inhibitor film formed on the steel surface. [ABSTRACT FROM AUTHOR]

Objectives The definition of work-related Asthma (WRA) has changed in recent years and new etiologies and agents have been identified. The aim of this study is to describe the main causal agents of WRA in France in the period 2001–2018 in the main work sectors. Methods Data were collected from the French national network of occupational health surveillance and prevention [Réseau National de Vigilance et de Prévention des Pathologies Professionnelles (RNV3P)], Data between 2001 and 2018 with at least a probable or certain association with one occupational agent, were included. Results Work sectors with more cases OF WRA included personal service activities (10.6%), food industry (10.2%) and healthcare activities (7.6%). WRA cases were most frequently related to flour (10%), quaternary ammoniums compounds (5.3%), isocyanates (5.1%) and cleaning products (4.8%). Conclusion Occupational exposure to specific agents capable of causing WRA is still present, and four agents represent more than 25% of the cases. Actions to prevent respiratory exposure are still relevant. [ABSTRACT FROM AUTHOR]

High prevalence and poor control of hypertension have been observed in populations with low-socioeconomic status. Comparing an unemployed population with another employed population sharing the same culture, and another employed population living in another environment might enlighten the effects of factors accessible to primary prevention on the one hand and access to health care on the other hand. The objectives are, first, to describe blood pressure (BP) prevalence and control in an unemployed Caribbean population benefiting from State financial support and good access to health care and second, compare the results in this population with those observed, with the same methodology in two employed populations, one in the Caribbean and one in metropolitan France. A cross-sectional study of 2420 consecutive unemployed subjects referred for check-up in the two health centres of Guadeloupe, a French Caribbean island. Hypertension prevalence was 25.2% in men and 22.1% in women. BP was controlled in 17.3% of men and 37.2% of women receiving antihypertensive medication. Among women, 58% were overweight and 29% obese. Prevalence of hypertension was higher among the unemployed and employed Caribbean population, than among an employed metropolitan French population. A high prevalence of obesity was observed in the two Caribbean populations suggesting the interest of primary prevention in the Caribbean. Burden of hypertension in a population relates to the development of hypertension (primary prevention) and control of hypertension (secondary prevention). Identifying hypertensive patients and controlling blood pressure are both important to reduce the disease burden.Journal of Human Hypertension (2007) 21, 316–322. doi:10.1038/sj.jhh.1002150; published online 8 February 2007 [ABSTRACT FROM AUTHOR]

The inhibitory effect of an oxalic type organic compound oxalic N-phenylhydrazide-N′-phenylthiosemicarbazide on the corrosion of carbon steel in 0·5M H2SO4 aqueous solution was investigated by different experimental methods; gravimetry, voltammetry and electrochemical impedance spectroscopy. The surface state of the electrode after immersion of the steel coupons in corrosion test solutions, in absence and in presence of the inhibitor was characterised by scanning electron microscopy. The potentiodynamic polarisation measurements showed that the presence of the inhibitor in 0·5M H2SO4 decreased both cathodic and anodic processes. The action of this inhibitor is therefore of a mixed type. The electrochemical impedance measurements showed the adsorption of the inhibitor. The inhibitory efficiency reaches a value of 95% at an inhibitor concentration of 10−3M. [ABSTRACT FROM AUTHOR]

Corrosion inhibition by triazole derivatives ( n-MMT) on mild steel in 5 % hydrochloric acid (HCl) solutions has been investigated by weight loss and electrochemical methods. The results obtained revealed that these compounds performed excellently as corrosion inhibitors for mild steel in HCl solution. Potentiodynamic polarization studies showed that they suppressed both the anodic and cathodic processes and inhibited the corrosion of mild steel by blocking the active site of the metal. The effect of temperature on the corrosion behavior of mild steel in 5 % HCl with the addition of different concentrations of the inhibitors was studied in the temperature range from 303 to 333 K. The associated activation corrosion and free adsorption energies were determined. The adsorption of these compounds on the mild steel surface obeys the Langmuir adsorption isotherm. The effect of molecular structure on the inhibition efficiency has been investigated by quantum chemical calculations. The electronic properties of inhibitors were calculated and are discussed. [ABSTRACT FROM AUTHOR]

A new corrosion inhibitor, namely 5-(2-hydroxyphenyl)-1,2,4-triazole-3-thione (5-HTT), has been synthesized and its influence on corrosion inhibition of mild steel in 5 % HCl solution has been studied using weight loss method and electrochemical measurements. Potentiodynamic polarization measurements clearly reveal that the investigated inhibitor is of mixed type, and it inhibits the corrosion of the steel by blocking the active site of the metal. Changes in impedance parameters were indicative of adsorption of 5-HTT on the metal surface, leading to the formation of protective films. The degree of the surface coverage of the adsorbed inhibitors was determined by weight loss measurements, and it was found that the adsorption of these inhibitors on the mild steel surface obeys the Langmuir adsorption isotherm. The effect of the temperature on the corrosion behavior with addition of 5 × 10 M of the inhibitor was studied in the temperature range 30-60 °C. The reactivity of this compound was analyzed through theoretical calculations based on density functional theory to explain the different efficiency of these compounds as a corrosion inhibitor. [ABSTRACT FROM AUTHOR]

The aims of our study were: (i) to estimate the yearly incidence rates based on one vs two visits in a working population and (ii) to identify incident hypertension modifiable risk factors. A total of 21?566 normotensive subjects were included in a 1-year cohort study. Blood pressure (BP) levels at inclusion and at the second year screening were measured on the basis of two visits, that is, if BP was over 140/90?mmHg in untreated subjects, they were invited to a control visit 1 month later. Height and weight were measured and behavioural risk factors were collected. Among the 17?465 subjects who completed the entire protocol (9691 men and 7774 women), 17?026 remained normotensive at a 1-year interval and 439 (325 men and 114 women) became hypertensive. Crude yearly incidence rates based on one visit were 6.21% in men and 3.06% in women, compared with 3.04% in men and 1.34% in women when incidence rates were based on two visits, a more than twofold difference. Age and body mass index at baseline were the two major independent determinants of incident hypertension in both genders. Smoking and alcohol consumption were significant risk factors in men but not in women, and a low educational level only in women. BP measurement on separate occasions is necessary to avoid overestimation of incidence. Weight in both genders and alcohol consumption in men were the main modifiable predictors of hypertension.Journal of Human Hypertension (2004) 18, 487-494. doi:10.1038/sj.jhh.1001682 Published online 12 February 2004 [ABSTRACT FROM AUTHOR]