Whilst the oxidation of Fe(II) in aerobic conditions has been studied thoroughly, an in-depth knowhow on the fate or stability of Fe(II) in solutions with near-neutral pH under anaerobic conditions is still lacking. Here, we experimentally investigated the kinetics of Fe(II) oxidation in solutions with pH ranging between ∼5 and 9, under aerobic (when solutions were in equilibrium with atmospheric oxygen) and anaerobic conditions (when the dissolved oxygen concentration was ∼10 mol/L), by colorimetric means. Experimental results and thermodynamic considerations presented here, show that Fe(II) oxidation in anaerobic conditions is first-order w.
View Article and Find Full Text PDFJ Colloid Interface Sci
February 2022
Both, experimental and modelling evidence is presented in this study showing that interlayer anion exchange is the dominant sorption mechanism for iodide (I) on AFm phases. AFm phases are Ca-Al(Fe) based layered double hydroxides (LDH) known for their large potential for the immobilization of anionic radionuclides, such as dose-relevant iodine-129, emanating from low- and intermediate-level radioactive waste (L/ILW) repositories. Monosulfate, sulfide-AFm, hemicarbonate and monocarbonate are safety-relevant AFm phases, expected to be present in the cementitious near-field of such repositories.
View Article and Find Full Text PDFFungal biofilm-related infections are increasingly occurring. We previously identified a fungicidal antibiofilm combination, consisting of miconazole (MCZ) and the quaternary ammonium compound domiphen bromide (DB). DB eliminates tolerance rather than altering the susceptibility to MCZ of various spp.
View Article and Find Full Text PDFAn increasing number of people is affected by fungal biofilm-based infections, which are resistant to the majority of currently-used antifungal drugs. Such infections are often caused by species from the genera or Only a few antifungal drugs, including echinocandins and liposomal formulations of amphotericin B, are available to treat such biofilm-based fungal infections. This review discusses combination therapy as a novel antibiofilm strategy.
View Article and Find Full Text PDFAntimicrob Agents Chemother
September 2020
The occurrence and recurrence of mucosal biofilm-related infections, such as oral and vulvovaginal candidiasis, are serious clinical issues. Vaginal infections caused by spp., for example, affect 70 to 75% of women at least once during their lives.
View Article and Find Full Text PDFSafety assessment studies of future nuclear waste repositories carried out in many countries predict selenium-79 to be a critical radionuclide due to its presence as anion in three relevant oxidation states (vi, iv, -ii) resulting in weak retardation by most common rock minerals. This assumption, however, ignores its potential uptake by AFm phases, positively charged anion exchangers, which are present in significant quantities in the cementitious materials used in artificial barriers. Here we report for the first time wet chemistry and spectroscopic data on the interaction of the most relevant selenium anion species under the expected strongly reducing conditions, i.
View Article and Find Full Text PDFBackground: Comparing the dynamic pedobarographic patterns of individuals is common practice in basic and applied research. However, this process is often time-consuming and complex, and commercially available software often lacks powerful visualization and interpretation tools.
Methods: We propose a simple method for displaying pixel-level pedobarographic deviations over time relative to a so-called reference pedobarographic pattern.
Comparing plantar pressure measurements (PPM) of a patient following an intervention or between a reference group and a patient-group is common practice in clinical gait analysis. However, this process is often time consuming and complex, and commercially available software often lacks powerful visualization and interpretation tools. In this paper, we propose a simple method for displaying pixel-level PPM deviations relative to a so-called reference PPM pattern.
View Article and Find Full Text PDFNon-selective luminescence spectroscopy and luminescence line-narrowing spectroscopy were used to study the retention of UO2(2+) on titanium dioxide (TiO2), synthetic calcium silicate hydrate (C-S-H) phases and hardened cement paste (HCP). Non-selective luminescence spectra showed strong inhomogeneous line broadening resulting from a strongly disordered UO2(2+) bonding environment. This problem was largely overcome by using luminescence line-narrowing spectroscopy.
View Article and Find Full Text PDFUnlabelled: Hypoglycemia is common in daily clinical practice and often occurs during the treatment of diabetes mellitus. However, a small minority of hypoglycemia encountered in clinical practice is spontaneous and thus not induced by glycemic lowering agents. These spontaneous hypoglycemic events confront the clinician with a diagnostic enigma.
View Article and Find Full Text PDFBackground: The aim of this study was to identify groups of subjects with similar patterns of forefoot loading and verify if specific groups of patients with diabetes could be isolated from non-diabetics.
Methodology/principal Findings: Ninety-seven patients with diabetes and 33 control participants between 45 and 70 years were prospectively recruited in two Belgian Diabetic Foot Clinics. Barefoot plantar pressure measurements were recorded and subsequently analysed using a semi-automatic total mapping technique.
Background: Reduction in foot mobility has been identified as a key factor of altered foot biomechanics in individuals with diabetes mellitus. This study aimed at comparing in vivo segmental foot kinematics and coupling in patients with diabetes with and without neuropathy to control adults.
Methods: Foot mobility of 13 diabetic patients with neuropathy, 13 diabetic patients without neuropathy and 13 non-diabetic persons was measured using an integrated measurement set-up including a plantar pressure platform and 3D motion analysis system.
Introduction: Data on switching from premixed insulin to a basal-bolus regimen in routine clinical practice are sparse. The aim was to evaluate the efficacy and safety of switching from twice-daily premixed insulin to basal glargine plus rapid-acting insulin in a "real-world" clinical practice setting in Belgium and The Netherlands.
Methods: This prospective, 6-month, noninterventional, observational study was conducted in 37 centres in Belgium and 19 centres in The Netherlands.
Nuclear waste disposal concepts developed worldwide foresee the use of cementitious materials for the immobilization of long-lived intermediate level waste (ILW). This waste form may contain significant amounts of neptunium-237, which is expected to be present as Np(IV) under the reducing conditions encountered after the closure of the repository. Predicting the release of Np(IV) from the cementitious near field of an ILW repository requires a sufficiently detailed understanding of its interaction with the main sorbing components of hardened cement paste (HCP).
View Article and Find Full Text PDFBatch sorption experiments and time-resolved luminescence spectroscopy investigations were carried out to study the U(VI) speciation in calcium silicate hydrates for varying chemical conditions representing both fresh and altered cementitious environments. U(VI) uptake was found to be fast and sorption distribution ratios (R(d) values) were very high indicating strong uptake by the C-S-H phases. In addition a strong dependence of pH and solid composition (Ca:Si mol ratio) was observed.
View Article and Find Full Text PDFJ Colloid Interface Sci
February 2010
Calcium silicate hydrate (C-S-H) phases control the immobilization of many metal cations in cementitious materials. In this study Nd binding to amorphous C-S-H phases with different Ca/Si (C/S) mol ratios (0.56, 0.
View Article and Find Full Text PDFDiabetes Metab
September 2009
Aims: We examined whether parenteral regular insulin can prevent diabetes in IA-2 antibody-positive (IA-2A+) relatives of type 1 diabetic patients, using a trial protocol that differed substantially from that of the Diabetes Prevention Trial-1.
Methods: Twenty-five IA-2A+ relatives received regular human insulin twice a day for 36 months, during which time they were followed (median [interquartile range; IQR]: 47 [19-66] months) for glucose tolerance, HbA(1c) and islet autoantibodies, together with 25 IA-2A+ relatives (observation/control group) who fulfilled the same inclusion criteria, but were observed for 52 [27-67] months (P=0.58).
Wet chemistry experiments and X-ray absorption fine structure (XAFS) measurements were carried out to investigate the immobilization of nonradioactive Sr and 85Sr in calcite-free and calcite-containing Portland cement. The partitioning of pristine Sr between hardened cement paste (HCP) and pore solution, and the uptake of 85Sr and nonradioactive Sr were investigated in batch-type sorption/desorption experiments. Sr uptake by HCP was found to be fast and nearly linear for both cements, indicating that differences in the compositions of the two cements have no influence on Sr binding.
View Article and Find Full Text PDFAim: This trial evaluated the potential for improving glycaemic control by intensifying a conventional twice-daily therapy with premixed human insulin (HI) to a thrice-daily regimen using premixed formulations of biphasic insulin aspart (BIAsp) in patients with type 1 or type 2 diabetes.
Methods: This was a multicentre, open-label, parallel group trial. After a 4-week run-in period, patients were randomized 1 : 1 to 16 weeks of treatment.
Among the different cement minerals, calcium silicate hydrates (C-S-H) are the prime candidates for heavy metal binding because of their abundance and appropriate structure. Immobilization processes of heavy metals by cementitious materials, and in particular C-S-H phases, thus play an important role in multibarrier concepts developed worldwide for the safe disposal of hazardous and radioactive wastes. In this study, the uptake of U(VI) by C-S-H has been investigated using X-ray absorption fine structure (XAFS) spectroscopy.
View Article and Find Full Text PDFIn the present study the binding of strontium with pure calcium silicate hydrates (C-S-H) has been investigated using batch-type experiments. Synthetic C-S-H phases with varying CaO:SiO(2) (C:S) mol ratios, relevant to non-degraded and degraded hardened cement paste, were prepared in the absence of alkalis (Na(I), K(I)) and in an alkali-rich artificial cement pore water (ACW). Two types of experimental approaches have been employed, investigating sorption and co-precipitation processes, respectively.
View Article and Find Full Text PDFThe curium(III) interaction with cement was investigated using time-resolved laser fluorescence spectroscopy at trace concentrations. Four different Cm(III) species were identified: a nonfluorescing species which corresponds to curium hydroxide real colloids, which were characterized in detail by laser-induced breakdown detection (LIBD), a fluorescing Cm(III)/portlandite sorption species, and two fluorescing Cm(III)/calcium silicate hydrate (CSH) species. From the fluorescence emission lifetimes it is predicted that the two fluorescing Cm(III)/CSH species have one to two and no water molecules, respectively, left in their first coordination sphere, suggesting that these species are incorporated into the CSH structure.
View Article and Find Full Text PDFThe interaction of the two chemical homologues [Cm(III) and Eu(III)] with calcium silicate hydrates (CSH phases) at pH 13.3 has been investigated in batch-type sorption studies using Eu(III) and complemented with time-resolved laser fluorescence spectroscopy (TRLFS) using Cm(III). The sorption data for Eu(III) reveal fast sorption kinetics and a strong uptake by CSH phases with distribution ratios of (6 +/- 3) x 10(5) L kg(-1).
View Article and Find Full Text PDFJ Contam Hydrol
March 2003
Diffusion experiments through hardened cement pastes (HCP) using tritiated water (HTO) and 22Na(+), considered to be conservative tracers, have been carried out in triplicates in a glove box under a controlled nitrogen atmosphere. Each experiment consisted of a through-diffusion test followed by an out-diffusion test. The experimental data were inversely modelled applying an automated Marquardt-Levenberg procedure.
View Article and Find Full Text PDFJ Synchrotron Radiat
March 2001
X-ray absorption fine structure (XAFS) spectroscopy was applied to assess the solubility-limiting phase of Ni in cement and cement minerals. The study reveals the formation Ni and Al containing hydrotalcite-like layered double hydroxides (Ni-Al LDHs) when cement material (a complex mixture of CaO, SiO2, Al2O3, Fe2O3 and SO3) was treated with Ni in artificial cement pore water under highly alkaline conditions (pH = 13.3).
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