Removal of Heavy Metal Impurities from Dredged River Sediment

This article shows the results of a study that aims to remove the sediment fraction containing heavy metals from river sediment by flotation. Different parameters such as pH, flotation time, different collectors, distilled water, tap water, and different salts were investigated to achieve a high separation efficiency. Explanations are suggested for the obtained results. Results of flotation revealed that 63 % by weight of the input dredged sediment can be safely and successfully separated, thus, meeting the standard environmental requirement of current Flemish (Belgium) regulation “bodemsaneringsdecreet” (February 1995). This dredged fraction could not be achieved before a flotation time of 15 min. Increasing flotation time would impart less metal content but with a lower yield. In the case of applying the settling technique, 55 % by weight of the dredged sample meeting the same standard specification was obtained. Results are explained in the light of a model, which assumes that sediment contains organic matter together with heavy metals, clay, and sand. Upon aeration, air bubbles are adsorbed on hydrophobic particles, which carry them up to the froth layer with the hydrophilic particles left behind in the pulp. The use of an organic collector has a minor effect on flotation process. Results of the settling technique are discussed.     

Identification of Phenylphthalazinones as a New Class of Leishmania infantum Inhibitors

Leishmaniasis is a neglected parasitic disease caused by over 20 different Leishmania species. Current treatments often rely on harsh regimes of pentavalent antimonials such as sodium stibogluconate, while more recent drugs suffer other shortcomings such as low stability and rapid emergence of treatment failure, amongst others. Furthermore, the effectiveness of drugs varies depending on the infecting Leishmania species, thus there is an urgent need for new and effective anti-leishmanial drugs. Screening of an in-house compound library identified the hexahydrophthalazinone NPD-2942 as a low micromolar hit with a pIC₅₀ of 5.8 against L. infantum and a pIC₅₀ of 4.6 for cytotoxicity against human MRC-5 fibroblasts. To derive structure–activity relationships, we modified the cyclohexyl ring of the hexahydrophthalazinone scaffold and 1,2,3-triazoles were attempted as replacement for the pyrazole ring, amongst others. Ultimately, the 2,3-pyrazole-substituted hexahydrophthalazinone NPD-1289 was identified as the most potent analogue in this series with a pIC₅₀ of 6.3, although some cytotoxicity toward MRC-5 cells (pIC₅₀=5.1) was recorded as well. Replacement of the unsubstituted 2,3-pyrazole with 1,2,3-triazoles led to compounds with lower anti-leishmanial activity. The current scaffold is a valuable new starting point for optimization toward novel anti-leishmanial drugs.     

Theoretical evaluation of pillared clay adsorbents: Part III: The total porosity and the macrostructure of Al-pillared montmorillonite and hectorite

As a new class of porous materials, pillared clays have been more and more investigated as a potential substituent or complement to zeolite materials. Despite of intensive research, real industrial applications are still lacking. Somehow, the porosity of these materials is lower than what was expected. To evaluate the potential of the pillared clays as adsorbent, theoretical calculations were carried out to obtain a better insight of the influence of the PILC's macrostructure on the micro- and mesoporosity.Assuming the layers to stack in a 3-dimensional brick-like fashion, the micro- and mesoporosity and interpillar free distance were calculated taking into account: the clay layer dimensions, interlayer free spacing, lateral distance between adjacent layers, partial pillaring/collapse and pillar symmetry. The calculations were performed for Al-pillared montmorillonite and hectorite and validated with experimental results.Nomenclature a height of the mesopore - Al-pilM aluminium pillared montmorillonite - Al-pilH aluminium pillared hectorite - b lateral distance between two stacks - CEC cation exchange capacity meq/g - d _pp interpillar free distance - H height of a clay layer Å - IFS interlayer free spacing Å - L length and width of a clay layer Å - P pillar height Å - pil/g number of pillars in 1 g clay - (pil/g)_in number of pillars, in 1 g clay, intercalated between the layers - (pil/g)_out number of pillars, in 1 g clay, not intercalated - (pil/g)_tot total number of pillars in 1 g clay - pl/g number of clay layers in 1 g clay - s number of layers in a stack - SA^av layer surface area available for pillaring m²/g - SA_BET BET surface area m²/g - SA_max maximum surface area of the clay layers m²/g - SA _meso ^av available surface area in the mesopores m²/g - Ustr unit structure - Ustr/g number of unit structures in 1 g clay - V_free free volume in the unit structure - V _meso ^av calculated available mesopore volume cc/g - V _meso ^ult calculated ultimate mesopore volume cc/g - V _micro ^av calculated available micropore volume cc/g - V _micro ^ult calculated ultimate micropore volume cc/g - V_1pil volume of one pillar cc/g - V_pil(in) total volume of the pillars between the layers cc/g - V_pil(out) total volume of the pillars outside the layers cc/g - V_tot total pore volume atp/p ₀ = 0.98 cc/g - W_pil width of a pillar Å - Wt%_pil weight percentage Al₂O₃ present as pillars     

Biological variability in serum vitamin E concentrations: relation to serum lipids

The components of biological variation in serum vitamin E in relation to serum cholesterol, triglycerides, high- and low-density lipoprotein cholesterol (HDL-C, LDL-C), apolipoprotein A-I (apo A-I), and apo B were examined in 26 healthy volunteers who had monthly blood samplings during one calendar year. The estimated CVs for vitamin E were: interindividual, 19.9%, and intraindividual, 11.9%; the index of individuality (I-index) was 0.59. The I-indices for all lipid variables were < 0.51. Serum concentrations of vitamin E, cholesterol, triglycerides, HDL-C, LDL-C, and apo B were lower in spring than in the other seasons. The peak-trough differences in the yearly variations, expressed as a percentage of the mean, were for vitamin E 14.5%, cholesterol 16.2%, triglycerides 14.5%, and LDL-C 24.3%. A significant common annual rhythm was expressed in vitamin E or lipid variables and in the changes in ambient temperature the weeks before blood sampling (inverse relations). There were highly significant positive time relations between serum vitamin E and cholesterol, triglycerides, and apo B. Subjects with higher homeostatic setpoints of cholesterol showed higher homeostatic setpoints of vitamin E, triglycerides, LDL-C, and apo B.     

In vitro comparative assessment of the antioxidant activity of nacystelyn against three reactive oxygen species

Thiol-containing molecules possess antioxidant properties that are of interest in the pharmacological inactivation of reactive oxygen species (ROS), particularly in the treatment of chronic inflammatory respiratory diseases. In the present study, the in vitro antioxidant activity of a new agent was examined and compared with other thiol containing molecules, N-acetylcysteine (NAC) and captopril. Nacystelyn (CAS 89344-48-9, NAL) is a L-lysine salt of NAC having demonstrated several advantages as compared to NAC. The deoxyribose assay used for assessing the scavenging effect of drugs against hydoxyl radicals (.OH) first showed a prooxidant effect for thiols at relatively low concentrations that was attributed to a reduction of Fe(III) ions added in the system. This interference could be corrected by increasing ascorbate concentration. Second order rate constants for reaction with OH were calculated by extrapolation of the linear part of competition plots. Both NAL and NAC appeared as potent .OH scavengers (Ks > 10(10) mol-1 s-1) and reacted faster than captopril. The horseradish peroxidase assay for assessing the activity of thiols against H202 could not be used because thiol derivatives were substrates for the enzyme. By using the dithio-bis-nitrobenzoic acid (DTNB) assay, first order rate constants for reaction with H2O2 were obtained showing that both NAL and NAC reacted quite slowly with this species (K approximately equal to 0.03 min-1) although faster than captopril. Finally, the elastase-alpha 1-antiproteinase assay for assessing the activity of thiols against HClO again demonstrated the superiority of NAC and NAL over captopril, but this time, NAL was more efficient in maintaining the protease/antiprotease balance than NAC. This last observation may be of importance and deserves further investigation as HClO has been implicated in lung tissue damages during inflammatory respiratory diseases.     

Performance and reliability aspects of FOND: a new deep submicronCMOS device concept

The electrical performance and the hot-carrier degradation behavior of a new type of fully overlapped device called FOND (Fully Overlapped Nitride-etch defined Device) is analyzed and compared to that of conventional LDD devices. Similar current driveability is found for the FOND devices compared to conventional LDD devices although in the FOND device significantly smaller concentrations are used for the lightly doped n^--regions. For the overlapped device, a higher gate and overlap capacitance is found, originating from a larger poly length and self-alignment of the junction implant to the poly. For identical voltage conditions, this is reflected in a somewhat lower ring oscillator speed, compared to the LDD case. Concerning reliability, it is shown that deep submicron FOND devices can easily exceed the lifetime of the conventional LDD devices by two orders of magnitude. Based on experimental and simulation results, this higher hot-carrier resistance is explained by a smaller hot-carrier generation and a lower sensitivity of the overlapped device to hot-carrier damage. For the nMOS transistors, the lower generation of damage is the result of the lower lateral electric field due to the low n^- concentration and the overlap of the polysilicon gate on the n^- region while the suppressed sensitivity is due to the complete overlap. Compared to LDD devices, the use of fully overlapped devices creates a wider process and reliability margin that can be used to optimize other electrical parameters     

Automated contour detection of the left ventricle in short axis view in 2D echocardiograms

This paper describes a semi-automatic system for the extraction of the endocardial border on a sequence of two-dimensional short axis echocardiograms. The delineation in the images is based on a dynamic programming technique which takes into consideration the radial and tangent gradient, the intensity, the smoothness of the extracted contour and a rough estimation of the location of the contour, derived from the previous frame of the time sequence. For the first frame, the user is asked to specify a region of interest. Within this region of interest, the developed system defines a circle as a rough estimation of the location of the endocardium. The developed system allows iteration of the delineation process to obtain a more detailed outline of the endocardium. The outlined contours on successive echo-frames are verified as the system compares their areas. This verification is important since the delineation process is purely sequential and errors occurring in an intermediate frame of the time sequence may influence the results in the subsequent frames.     

13C-Octanoic acid breath test for gastric emptying rate of solids

We performed a retrospective chart review of 60 patients after mechanical heart valve replacement to assess warfarin sensitivity. The overall international normalized ratio (INR) on day 3 of therapy was 4.1+/-3.9 (range 1.1-17.1). In a control group of 100 patients who received anticoagulation for atrial fibrillation, pulmonary embolism, and deep vein thrombosis, the overall mean INR at day 3 was 1.9+/-0.7 (range 1.0-4.9). The difference between groups was statistically significant (p<0.05). We conclude that patients receiving warfarin after mechanical heart valve replacement are more sensitive to the drug than those receiving it for other indications, and reduced dosages may be necessary during the first 3 days after valve replacement.