Towards electrochemical iridium recycling in acidic media: effect of the presence of organic molecules and chloride ions.

The utilization of iridium is expected to surge in the next few years, notably due to the rising implementation of water electrolyzer devices in the energy transition. However, the natural resources of this noble metal are extremely limited and thus its recycling will become of high importance. Unfortunately, iridium is also the most corrosion resistant platinum group metal, making its recovery from waste a difficult and energy-demanding process. Hereby, we study the impact of organics and chloride ions on the electrochemical dissolution of iridium in order to pave the way towards green recycling of this precious metal. We present a 40 times increased dissolution when cycling iridium in presence of HCl and 1 M ethanol compared to HClO4. Our results point towards the direction of destabilizing Ir at relatively mild conditions in acidic media.

Development of a reference material for analysing naturally occurring radioactive material from the steel industry.

Accurate measurement of naturally occurring radionuclides in blast furnace slag, a by-product of the steel industry, is required for compliance with building regulations where it is often used as an ingredient in cement. A matrix reference blast furnace slag material has been developed to support traceability in these measurements. Raw material provided by a commercial producer underwent stability and homogeneity testing, as well as characterisation of matrix constituents, to provide a final candidate reference material. The radionuclide content was then determined during a comparison exercise that included 23 laboratories from 14 countries. Participants determined the activity per unit mass for 226Ra, 232Th and 40K using a range of techniques. The consensus values obtained from the power-moderated mean of the reported participant results were used as indicative activity per unit mass values for the three radionuclides: A0(226Ra) = 106.3 (34) Bq·kg-1, A0(232Th) = 130.0 (48) Bq·kg-1 and A0(40K) = 161 (11) Bq·kg-1 (where the number in parentheses is the numerical value of the combined standard uncertainty referred to the corresponding last digits of the quoted result). This exercise helps to address the current shortage of NORM industry reference materials, putting in place infrastructure for production of further reference materials.

Melatonin modulate the expression of α1- and ß2-adrenoceptors in the hippocampus of rats subjected to unpredictable chronic mild stress.

OBJECTIVE: This study investigated the effects of chronic melatonin treatment on gene expression of α1-, α2-, ß1- and ß2-adrenoceptors in the hippocampus of rats subjected to chronic unpredictable mild stress (CUMS). BACKGROUND: Preclinical studies have also shown that melatonin prevented short- and long-term memory impairments and exhibited antidepressant-like actions. METHODS: For this study, we used 24 animals, which were divided into four groups, and the experiment lasted 4 weeks. We quantified the changes in mRNA and protein levels of α1-, α2-, ß1- and ß2-adrenoceptors in the hippocampus after melatonin treatment. RESULTS: Our results demonstrated a decreased gene expression of α1-, α2- and ß2-adrenoceptors in the hippocampus of rats subjected to unpredictable chronic mild stress, while there was no change in gene expression of ß1-adrenoceptors. Melatonin treatment in the CUMS rats prevented the stress-induced decrease in mRNA and protein levels of α1-and ß2-adrenoceptors, whereas did not affect either on mRNA or protein level of ß1-and α2-adrenoceptors. CONCLUSION: Our data suggest that melatonin, by increasing reduced levels of α1- and ß2-adrenoceptors mRNA and protein in the hippocampus of chronic stressed rats, may be beneficial in conditions such as chronic stress and provides an experimental opportunity to probe into further molecular mechanisms underlying the regulation of these receptor subtype (Fig. 2, Ref. 28).

Anxiety and Hyperlocomotion Induced by Chronic Unpredictable Mild Stress Can Be Moderated with Melatonin Treatment.

Preclinical studies have shown that melatonin exercised antidepressant-like and anxiolyticlike effects in animal models of anxiety. The aim of the present study was to correlate the changes in behaviour induced by melatonin treatment with the activity of the dopaminergic system in the hippocampus of Wistar rats exposed to chronic, unpredictable, mild stress (CUMS). Male Wistar rats, 11 weeks old, were subjected to chronic stress for 28 successive days. Separate groups of control and stressed rats were intraperitoneally injected daily either with melatonin (10 mg/kg/day, i.p.) or placebo (5% ethanol). The open-field and elevated plus-maze tests were used to assess locomotor activities and anxiety levels. The content of dopamine (DA) in the hippocampal tissues was determined using radioenzymatic assay, while changes in tyrosine hydroxylase (TH) mRNA and protein levels in the hippocampus were determined using real-time RT-PCR and Western immunoblotting. Chronic stress led to reduction in the hippocampal dopaminergic content without affecting the levels of TH protein. These changes were accompanied by increased locomotor activity and higher anxiety levels in the open-field test. Administration of melatonin for 28 days resulted in an increase in the hippocampal DA content as a result of elevated TH protein levels. Melatonin showed an improvement in anxiety-like behaviour along with significantly reduced exploration. We could conclude that melatonin may stimulate dopaminergic synthesis in the hippocampus in order to suppress stress-induced behaviour.

A highly active PtCu3 intermetallic core-shell, multilayered Pt-skin, carbon embedded electrocatalyst produced by a scale-up sol-gel synthesis.

We present a novel, scaled-up sol-gel synthesis which enables one to produce 20 g batches of highly active and stable carbon supported PtCu3 nanoparticles as cathode materials for low temperature fuel cell application. We confirm the presence of an ordered intermetallic phase underneath a multilayered Pt-skin together with firm embedment of nanoparticles in the carbon matrix.

The influence of chloride impurities on Pt/C fuel cell catalyst corrosion.

Potentiodynamic Pt/C fuel cell catalyst corrosion has been studied as a function of chloride concentration with an electrochemical flow cell (EFC) coupled with highly sensitive ICP-MS. The Pt corrosion mechanism changes significantly: the anodic corrosion is much enhanced compared to the cathodic corrosion that prevails in electrolytes without Cl(-).

Differential expression of tyrosine hydroxylase and transporters in the right and left stellate ganglion of socially isolated rats.

Chronic isolation stress of adult rat males acted increasing gene expression of tyrosine hydroxylase (TH) and neuronal norepinephrine transporter (NET) in the right stellate ganglia, while vesicular monoamine transporter 2 (VMAT2) level remained unchanged. The stress decreased protein level of TH, as well as mRNA levels for NET and VMAT2 in the left stellate ganglia, but expressed no effect on protein levels of these two transporters. These results demonstrate asymmetry in noradrenergic genes in the right and left stellate ganglia during stress and provide molecular evidence to help explain the difference in response to the stress.

Copeptin level after carotid endarterectomy and perioperative stroke.

We evaluated the prognostic value of copeptin levels in a cohort of surgical patients after elective carotid endarterectomy (CEA). Twenty-one patients with perioperative stroke were prospectively recruited. The diagnosis of cerebrovascular event (CVE) was confirmed by computed tomography. Additionally, 21 patients with CEA without any complications (control patients) were enrolled. Blood samples were taken within 3 hours of the symptom onset. Circulating copeptin level was significantly higher in patients with CVE when compared to controls (P = .025), and significantly higher in nonsurvivors than in survivors (P = .030) after CVE. Plasma concentrations of interleukin 6 (IL-6) and C-reactive protein (CRP) were also elevated in patients with CVE (IL-6: P = .043; CRP: P = .002). We conclude that the activation of the stress axis in patients with CEA results with copeptin elevation, but more so in patients with perioperative stroke. Copeptin may be a helpful biomarker for stroke risk assessment in patients after CEA.

Peripheral oxytocin treatment affects the rat adreno-medullary catecholamine content modulating expression of vesicular monoamine transporter 2.

The neuropeptide oxytocin has been shown to influence on neuroendocrine function. The aim of the present study was to investigate the effect of peripheral oxytocin treatment on the synthesis, uptake and content of adreno-medullary catecholamine. For this purpose oxytocin (3.6µg/100g body weight, s.c) was administrated to male rats once a day over 14 days. In order to assess the effect of peripheral oxytocin treatment on adreno-medullary catecholamine we measured epinephrine and norepinephrine content and gene expression of tyrosine hydroxylase (TH), norepinephrine transporter (NET) and vesicular monoamine transporter 2 (VMAT2) in the adrenal medulla. Our results show a significant increase of epinephrine (1.7-fold, p<0.05) and norepinephrine (1.5-fold, p<0.05) content in oxytocin treated animals compared to saline treated ones. Oxytocin treatment had no effect either on mRNA or protein level of TH and NET. Under oxytocin treatment the increase in VMAT2 mRNA level was not statistically significant, but it caused a significant increase in protein level of VMAT2 (3.7-fold, p<0.001). These findings indicate that oxytocin treatment increases catecholamine content in the rat adrenal medulla modulating VMAT2 expression.

Molecular basis of chronic stress-induced hippocampal lateral asymmetry in rats and impact on learning and memory.

Neurochemical lateralization has been demonstrated in the rat brain suggesting that such lateralization might contribute to behavior. Thus, the aim of the present study was to examine neurochemical asymmetry in the hippocampus, molecular basis of neurochemical lateralization and its impact on spatial learning and memory. Changes in noradrenaline content, tyrosine hydroxylase (TH) were studied in the right and left hippocampus of naive control and chronically isolated rats, by applying TaqMan RT-PCR and Western blot analysis. Hippocampal-based spatial learning and memory were evaluated using the Barnes maze. In control rats an asymmetrical right-left distribution of noradrenaline content and gene expression of catecholamine synthesizing enzyme was found. Chronic psychosocial stress further emphasized asymmetry. Isolation stress reduced noradrenaline content only in the right hippocampus. No changes were observed in gene expression and protein levels of TH in the right hippocampus, whereas expression of catecholamine synthesizing enzyme was elevated in the left hippocampus. Reduced noradrenaline content in the right hippocampus did not cause impairment in spatial learning and memory. Our findings suggest that chronic psychosocial stress reduces noradrenaline stores in the right hippocampus which may be caused by molecular asymmetry, but it does not affect spatial learning and memory.

Flouxetine treatment acts selectively increasing myocardial beta1-adrenoceptor mRNA expression in stress-induced depression.

Changes in gene expression of beta1- and beta2-adrenoceptors (beta1 - and beta2-AR) in right and left atria and ventricles after fluoxetine treatment in stress-induced depression of adult rat males were studied. Elevated beta1-AR mRNA levels in the left atria and significantly higher levels of beta2-AR mRNA in the left atria and ventricles were observed in stress-induced depression in comparison with those of unstressed controls. Fluoxetine treatment led to increasing expression of beta1-AR mRNA in the right atria and left ventricles, while the level of beta2-AR mRNA remained unchanged. These findings suggest that fluoxetine therapy plays an important role in cardiac beta-adrenergic subsensitivity and gene regulation of beta-AR in animals with heightened sympathetic nervous activity.

Hemodialysis headache.

AIM: The aim of this study was to evaluate and analyze the incidence and features of headaches in patients undergoing hemodialysis. MATERIAL AND METHODS: In this prospective study 318 patients, 119 women and 199 men, undergoing chronic HD in four hemodialysis centers in Serbia, were questioned about their problems with headaches using a questionary designed according to the diagnostic criteria of the International Headache Classification of Headache Disorders (ICHD) from 2004. Patients were distributed in two groups according to the presence of hemodialysis headaches (HDH). The groups were compared regarding sex, age, duration of HD, primary diseases that lead to ESRD, arterial systolic and diastolic blood pressure (BP) and serum levels of hemoglobin, urea nitrogen, creatinine, sodium, potassium, calcium, phosphates, albumin, glucose and calcium-phosphate product. We also analyzed features of HDH. The results were statistically compared. RESULTS: Patients with HDH had significantly lower serum glucose, but higher serum phosphates and albumin than patients without headaches. Furthermore, HDH patients had higher calcium phosphate product and systolic blood pressure than non-HDH patients. Out of 318 patients included in the study, 21 (6.6%) patients had HDH. According to our results, HDH appeared more frequently in men, during the 3rd hour of HD in more than a half of the patients and lasted less then 4 h in the majority of HDH patients. In the majority of patients HDH was bilateral, non-pulsating, without associated symptoms and it appeared mostly during HD. Personal history was negative for primary headaches in all patients with HDH. CONCLUSION: We believe that the results of our investigation of more than 300 HD patients pointed to some biochemical changes, possibly implicated by pathophysiology of HDH and disclose some specific HDH features that might contribute to a better understanding of this secondary headache disorder.

Pseudoexfoliation syndrome and its antioxidative protection deficiency as risk factors for age-related cataract.

PURPOSE: Pseudoexfoliation syndrome (PES) seems to be a systemic condition. However, to an ophthalmologist it represents a continual challenge, due to unclear etiology and patho-genesis, and because of a potential for development of an aggressive glaucoma, and cataract surgery complications. According to some findings, PES could be a factor of hastened aging, which means that it could be considered as a secondary aging factor. METHODS: Frequencies of secondary aging diseases (non-insulin dependent diabetes mellitus, atherosclerotic myocardiopathy, chronic obstructive lung diseases, arterial hypertension, and PES) were investigated in 162 patients with age-related cataract and 55 age- and sex-matched control subjects, and analyzed by a logistic regression. The authors also determined elements of antioxidative protection in a group of sera from patients with cataract and PES, and compared them to those obtained from patients with cataract without PES (activity of catalase and peroxidase, glutathione, vitamins C and E), and total antioxidative protection (%iMDA). Antioxidant defense of aqueous humors, expressed as a rate of induced malondialdehyde (%iMDA), and total thiol groups in the lens corticonuclear blocks (TSH) were estimated in samples of 17 patients with PES and cataract and 55 patients with cataract only. RESULTS: Logistic regression showed the highest odds ratio for PES (OR=4.516; p<0.05). Catalytic activity of serum catalase had significantly lower values in patients with PES (p<0.05). Anti oxidative defense of aqueous humor and lens had lower values in patients with PES. CONCLUSIONS: The results indicate that PES might be a significant factor for cataractogenesis. At least a part of pathogenesis alterations in an eye with PES could be the result of higher intensity of oxidative stress.

Results of a simple intercomparison of natural radioactivity measurements using a 'blue concrete' sample.

A simple intercomparison of natural radioactivity and radon emanation factor measurements co-ordinated by the Medical Physics Department of the University of Cantabria UC, Spain, has been carried out during 1998 in the framework of the EU Concerted Action ERRICCA (European Research into Radon in Construction Concerted Action). All the measurements have been made on a 'blue concrete' sample kindly donated by Dr G. Akerblom from the Swedish Radiation Protection Institute. In addition to UC, two other participant laboratories, STUK from Finland and ZVD from the Republic of Slovenia, have contributed to the development of the intercomparison exercise. Considering the uncertainties of the measurements, a good agreement between the results obtained by the three participating laboratories has been ascertained. However, in accordance with experimental results obtained by other authors, data reported by UC show a significant decrease of the radon emanation factor as moisture content of the sample decreases below 5% (per weight).