The Inhibited Effect of Cysteine Towards the Corrosion of Copper in Nitric Acid Solution
The detailed study of cysteine (Cys) as corrosion inhibitor for copper in nitric acid solution has been performed through weight loss, electrochemical polarization, electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) measurements. The effect of inhibitor concentration, temperature and immersion time against inhibitor action was investigated. Results show that Cys may be used as an efficient inhibitor for copper in nitric acid at higher temperatures (98% at 50°C). Potentiodynamic polarization studies reveal that Cysteine acts as a mixed-type inhibitor without any change in the mechanism of hydrogen evolution. The adsorption of this compound on copper surface obeys Langmuir's adsorption isotherm and has a chemisorptions mechanism.
The effects of l-cysteine on the inhibition and accelerated dissolution processes of zinc metal
Effect of l-cysteine on the Zn dissolution in 0.5 M NaCl with initial pH of 4–12 was measured in continuously renewed electrolyte and in immersion tests. At short exposures 1 mM l-cysteine inhibited dissolution. The initial inhibition decreased with pH because of pH-enhanced dimerization of l-cysteine, confirmed by UV–vis spectroscopy. In long exposures at pH = 6–8 the inhibition turned into the acceleration. This was not observed at pH = 12. 10 mM l-cysteine accelerated Zn dissolution. The effects were explained by a competition between strong complexation of l-cysteine with Zn-ions and its weak physisorption on the substrate. The hypothesis was confirmed by surface characterizations.
Preparing for group analytic psychotherapy: meeting the new patient
Preparing for group analytic psychotherapy—the patient and yourself as a therapist—is apparently done in many ways and still invested with much controversy and ambivalence. Some say, they do no selection or assessment at all. The patients or clients are taken from the waiting list in alphabetic order. Other therapists—mainly those working in National Health Services—use several assessment interviews before including patients into short- or long-term groups. Either way, this article revives some research results about assessment and hopes to inspire therapists in their first contact with the patient by presenting some examples from a clinical outpatient practice in a mental health service.