Adsorption of Organic Acids on Metal Oxides. The Umbrella Effect

Simultaneous interpretation of electrokinetic and adsorption data for organic ions at metal oxide surfaces is introduced. It is shown that, for the salicylic acid / hematite system, the singly charged salicylate ions react with surface –OH, groups releasing one water molecule. The salicylate ions, when bound to the surface, exhibit a pronounced »Umbrella effect«, i.e. each relatively large organic ion covers about four to six surface –OH, excluding them from the further adsorption process. Within the electrical interfacial layer, the salicylate ions are located in the plane near the onset of the diffuse layer. It is demonstrated that the interpretation of adsorption data solely may lead to erroneous conclusions regarding the mechanism of binding and the structure of the interfacial layer. Electrokinetic measurements provide useful information, enabling the solution of the above problem

Preventing ectoparasite infestations reduces glucocorticoid concentrations in the hair of cows – short communication

The aim of this study was to compare hair corticosteroid concentrations in ectoparasiticide-treated (n = 10) and non-treated (n = 12) Holstein cows. Animals in the treated group received cyfluthrin three times, on days 0, 28 and 56 of the experiment. Hair samples were collected from all cows on days 0, 21, 42, 63, and 84 of the experiment for the determination of cortisol and corticosterone concentrations using immunoassays. The respective hair cortisol concentrations in the treated group averaged 209.78, 165.10, 260.78, 177.44 and 183.11 ng/g, while in the non-treated group hair cortisol concentrations averaged 172.58, 243.58, 309.73, 199.75 and 207.09 ng/g. These results indicate that the control of ectoparasites reduced hair cortisol levels in dairy cows. The respective hair corticosterone concentrations in the treated group averaged 19.06, 22.95, 21.95, 21.60 and 24.84 ng/g and in the non-treated group the hair corticosterone concentrations averaged 17.28, 21.94, 34.05, 26.27 and 26.91 ng/g. The results suggest that longterm stress can be estimated better by the determination of hair cortisol rather than corticosterone concentrations

Surgical site infection after gastrointestinal surgery in high-income, middle-income, and low-income countries: a prospective, international, multicentre cohort study

Background: Surgical site infection (SSI) is one of the most common infections associated with health care, but its importance as a global health priority is not fully understood. We quantified the burden of SSI after gastrointestinal surgery in countries in all parts of the world. Methods: This international, prospective, multicentre cohort study included consecutive patients undergoing elective or emergency gastrointestinal resection within 2-week time periods at any health-care facility in any country. Countries with participating centres were stratified into high-income, middle-income, and low-income groups according to the UN's Human Development Index (HDI). Data variables from the GlobalSurg 1 study and other studies that have been found to affect the likelihood of SSI were entered into risk adjustment models. The primary outcome measure was the 30-day SSI incidence (defined by US Centers for Disease Control and Prevention criteria for superficial and deep incisional SSI). Relationships with explanatory variables were examined using Bayesian multilevel logistic regression models. This trial is registered with ClinicalTrials.gov, number NCT02662231. Findings: Between Jan 4, 2016, and July 31, 2016, 13 265 records were submitted for analysis. 12 539 patients from 343 hospitals in 66 countries were included. 7339 (58·5%) patient were from high-HDI countries (193 hospitals in 30 countries), 3918 (31·2%) patients were from middle-HDI countries (82 hospitals in 18 countries), and 1282 (10·2%) patients were from low-HDI countries (68 hospitals in 18 countries). In total, 1538 (12·3%) patients had SSI within 30 days of surgery. The incidence of SSI varied between countries with high (691 [9·4%] of 7339 patients), middle (549 [14·0%] of 3918 patients), and low (298 [23·2%] of 1282) HDI (p < 0·001). The highest SSI incidence in each HDI group was after dirty surgery (102 [17·8%] of 574 patients in high-HDI countries; 74 [31·4%] of 236 patients in middle-HDI countries; 72 [39·8%] of 181 patients in low-HDI countries). Following risk factor adjustment, patients in low-HDI countries were at greatest risk of SSI (adjusted odds ratio 1·60, 95% credible interval 1·05–2·37; p=0·030). 132 (21·6%) of 610 patients with an SSI and a microbiology culture result had an infection that was resistant to the prophylactic antibiotic used. Resistant infections were detected in 49 (16·6%) of 295 patients in high-HDI countries, in 37 (19·8%) of 187 patients in middle-HDI countries, and in 46 (35·9%) of 128 patients in low-HDI countries (p < 0·001). Interpretation: Countries with a low HDI carry a disproportionately greater burden of SSI than countries with a middle or high HDI and might have higher rates of antibiotic resistance. In view of WHO recommendations on SSI prevention that highlight the absence of high-quality interventional research, urgent, pragmatic, randomised trials based in LMICs are needed to assess measures aiming to reduce this preventable complication

Unattached Fraction of Radon Decay Products as a Crucial Parameter for Radon Dosimetry in Postojna Cave

V letih od 1998 do 2001 smo v zraku Postojnske jame na najnižji točki merili koncentracijo radona (CRn) in radonovih kratkoživih razpadnih produktov (CRnDP), ravnotežni faktor (F), delež nevezanih radonovih razpadnih produktov (fun), zračni tlak (P), relativno vlažnost zraka v jami (RH) in temperaturo zraka v jami (Tin) ter zunaj (Tout). Poseben poudarek je bil na fun in na njegovi odvisnosti od vremenskih razmer. Vrednosti fun so bile v širokem razponu, od 0,10 do 0,68. Z uporabo novega dozimetrijskega modela smo na osnovi izmerjenih vrednosti fun izračunali dozne pretvorbene faktorje in ugotovili, da so bili znatno višji od 5 mSv/WLM, to je vrednosti, ki jo priporoča metodologija ICRP-65. Tako so dejanske doze, ki jih prejmejo jamski vodiči, v povprečju za faktor 8 poleti in za faktor 2,7 pozimi višje od vrednosti, ki jih dobimo po dosedanji metodologiji ICRP-65.Short-term summer and winter monitoring was carried out at the lowest point in Postojna cave, on air concentrations on radon (CRn) and radon decay products (CRnDP), the equilibrium factor (F) and unattached fraction of radon decay products (f un ), barometric pressure (P), relative air humidity in the cave (RH) and air temperature outside (T out ) and in the cave (T in ), with the emphasis on f un . Dose conversion factors (DCF) for mouth and nasal breathing were calculated from the f un values (ranging from 0.10 to 0.68) and effective doses for the employees in the cave were obtained. These signifi cantly exceed the doses based on the ICRP-65 methodology now in use

Radiocarbon Releases at the Krško Nuclear Power Plant

Since 1991, radiocarbon analyses of exhaust air have been part of the regular radioactivity monitoring program at the Krško Nuclear Power Plant (NPP), a Westinghouse 632 MWe pressurized water reactor (PWR). Activity of CO2 and hydrocarbons has been identified; the former contributes ca. 43%. A normalized release of total 14C of 0.219 TBgGWe-1a-1 was obtained. Indoor air 14C concentrations in selected rooms inside the plant have generally been 1000 Bq m-3 may be reached. Tree rings have shown slight enhanced 14C activity due to the operation of the plant.This material was digitized as part of a cooperative project between Radiocarbon and the University of Arizona Libraries.The Radiocarbon archives are made available by Radiocarbon and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202

Surface-nitrogen Removal Studied from Desorption Dynamics

The removal of adsorbed nitrogen from catalyst surfaces is one of the key processes in proceeding efficient catalytic treatments of nitrogen oxides in exhaust gases from automotive and stationary sources. This review summarizes the typical characteristics of three removal processes of surface-nitrogen on metal surfaces, i.e., (i) 2N(a) → Nz(g), (ii) N(a) + NO(a) → N2O(a) → N2(g) + O(a) and (iii) NO(a) + O(a) → NO2(a) → NO3-(a) → N2(g). In the first process desorbing N2 is collimating along the surface normal direction and is vibrationally excited because a large amount of the binding energy is released in the associative process. N2 in the second process collimates into a highly inclined direction on flat surfaces because N2O lies on the surface immediately before dissociation. These characteristics are exemplified to be useful to examine the reaction pathway of NOx decomposition on catalysts