A test-rig closed-loop flotation column was used to observe the effect of diesel oil (collector) and Flomin F-425 (frother) on mass yield and ash content for two Colombian coals: Caypa (northern ...zone) and Guachinte (southwestern zone). The coal samples of less than 38 µm (-400 M) were processed in a collector concentration range of 0,32 to 1,60 kg/ton of coal, as well as a frother concentration range of 10 to 50 ppm. The response surface methodology was used for the experimental test runs. The results showed that the maximum mass yield obtained by Caypa coal was 98,39% at 1,28 kg of collector/ton of coal and 40 ppm of frother concentration, whereas Guachinte coal obtained a maximum mass yield of 94,71% at 0,96 kg of collector/ton of coal and 30 ppm of frother concentration. In general, for Caypa coal, the mass yield tends to increase (low ash removal) with the collector and frother concentration increase; while the mass yield tends to decrease (high ash removal) for Guachinte coal when the collector concentration increases (low ash removal) at high frother concentrations. It is worth highlighting that the ash content of 0,65% obtained for Caypa coal is the lowest value reported in the literature while employing a test-rig loop flotation column in a single stage, which is considered to be an ultra-clean coal obtained by a physical cleaning process.
The oxidation of antioxidants by oxidizers imposes great challenges to both living organisms and the food industry. Here we show that the host–guest complexation of the carefully designed, positively ...charged, amphiphilic guanidinocalix5arene pentadodecyl ether (GC5A‐12C) and negatively charged oleic acid (OA), a well‐known cell membrane antioxidant, prevents the oxidation of the complex monolayers at the air–water interface from two potent oxidizers hydroxyl radicals (OH) and singlet delta oxygen (SDO). OH is generated from the gas phase and attacks from the top of the monolayer, while SDO is generated inside the monolayer and attacks amphiphiles from a lateral direction. Field‐induced droplet ionization mass spectrometry results have demonstrated that the host–guest complexation achieves steric shielding and prevents both types of oxidation as a result of the tight and “sleeved in” physical arrangement, rather than the chemical reactivity, of the complexes.
A coating with “sleeves” : The compact host–guest complexation of calixarene and oleic acid molecules prevents the oxidation of the complex monolayers at the air–water interface by the action of hydroxyl radicals and singlet oxygen.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Abstract Purpose To investigate the prognostic value of perfusion defect volume (PDvol) at dual-energy-CT-angiography (DE-CTA) in patients with acute pulmonary embolism (PE) by correlating PDvol with ...CTA-obstruction-scores (OS), CT parameters of right-ventricular-dysfunction (RVD), and adverse-clinical-outcome. Materials and methods DE-CTA of 60 patients (mean age: 65 ± 14.4 years) with PE were analyzed. Iodine maps were generated, and normalized PDvol – defined as volume of perfusion defects/total lung volume – was quantified. Furthermore, established prognostic parameters (Qanadli and Mastora-OS, and CT parameters of RVD) were obtained. CT parameters of RVD – namely the right ventricle/left ventricle (RV/LV) diameter ratio measured on transverse sections (RV/LVtrans), four-chamber views (RV/LV4ch), and RV/LV volume ratios (RV/LVvol) – were assessed. PDvol was correlated with OS, CT parameters of RVD and adverse clinical outcome (defined as the need for intensive care treatment or death). Results 10 of 60 patients with PE experienced adverse clinical outcome. Patients with adverse clinical outcome showed significantly higher PDvol (35 ± 11% vs. 23 ± 10%, p = 0.002), RV/LV ratios (RV/LV4ch 1.46 ± 0.32 vs. 1.18 ± 0.26, p = 0.005; RV/LVvol 2.25 ± 1.33 vs. 1.19 ± 0.56, p = 0.002) and higher Mastora global scores (52 vs. 13, p = 0.02) compared to those without adverse clinical outcome. A weak correlation was observed between PDvol and the Mastora global score ( r = 0.5; p = 0.0003), as well as between PDvol and RV/LV4Ch ( r = 0.432, p = 0.0006). No correlation was found between PDvol and the Qanadli score or the remainder of the RVD-CT parameters. Conclusion The extent of perfusion defects as assessed by DE-CTA correlates with adverse clinical outcome in patients with PE. Therefore, volumetric quantification of perfusion defects at DE-CTA allows the identification of low-risk patients who do not require intensified monitoring and treatment.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
A methodology was used to evaluate Low Temperature Ash (LTA) and High Temperature Ash (HTA) through Mössbauer Spectroscopy (MS). Siderite was the only Mössbauer Spectral presenting a good correlation ...between the spectral area and the ash content obtained by LTA and HTA. The calibration curves obtained for HTA and LTA gave a correlation coefficient of 0.968 and 0.988, respectively. The LTA results present the best correlation, given that this process does not change the original mineral phases. This methodology was the advantageous for easily obtaining coal ash content, through curve ash content vs. MS area, without carrying out ashing processes.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Plastics are widely used for various applications. Once discarded, it is commonly known that they represent a high environmental threat due to their slow degradation; for this reason, there is an ...imminent need to replace these products with eco-friendlier ones. In the present work, four bacterial polyhydroxybutyrate (PHB) producers, two consortia, and two isolated strains were successfully recovered from the facilities of a paper-manufacturing industry. Spectroscopic studies of the biopolymers obtained from these bacteria corroborated their PHB production capabilities, ranging from 4.04 ± 0.16 to 23.82 ± 3.39 g/L. The characterization of the isolate that presented the highest production yield initially coded as E22 led to the identification of a
Klebsiella pneumoniae
strain, which, compared with other PHA bacterial producers reported to date, could be considered with high production potential. The strain E22 was grown in 5 different media prepared from fruit peel residues of banana, orange, papaya, watermelon, and melon, to determine its growth and PHA production capabilities in these low-cost media. The results obtained show different bacterial growth yields among the media tested, although PHB production yields and productivities were similar in all these low-cost media. Cellular accumulation of the biopolymer was higher in watermelon peel medium (8.4 × 10
−10
g/CFU). These results reveal the potential of
K. pneumoniae
E22 for PHB production applications and establish encouraging alternatives to be broader explored regarding low-cost media that could enhance the scale-up of bacterial PHA production processes.
Graphical abstract
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The aim of this study was to explore the relationships between a Gram-positive bacterial population and methane production in the rumen of dairy cows supplemented with monensin and tallow, alone or ...in combination. Under each treatment condition, the following ruminal fermentation parameters were measured: pH, oxidation-reduction potential (ORP), VFA, and methane production. Quantification of Gram-positive bacteria present in the rumen was performed by amplifying the 16S rDNA gene using PCR. Diversity analysis of Gram-positive bacteria was performed by PCR–denaturing gradient gel electrophoresis (DGGE), and bacterial taxonomy data were obtained by bioinformatics tools. Neither additive affected the pH or ORP, but they both reduced the total quantity of VFA. Supplementation with monensin, tallow, or their combination caused a decrease in methane production compared to the control diet. The best treatment to reduce methane production was monensin, with a reduction of 7.2% compared to the control diet. Supplementation with monensin or tallow did not affect the bacterial population. The Shannon diversity index was higher with monensin supplementation than with the other treatments. The analysis of each DGGE microbial community by the unweighted pair group method with averaging (UPGMA) revealed two clusters, one group with the control and monensin diets and the other with the tallow and combination diets. Taxonomic analysis of the dominant bands from the DGGE gel with the use of the Ribosomal Database Project (RBP) revealed that the Ruminococcaceae family was predominant, followed by the Lachnospiraceae family. Correspondence analysis (CA) suggested that both were negatively correlated with methane production in all treatments.
Geopolymers are considered alternative materials to ordinary Portland cement (OPC) with similar or superior properties. SiC imparts interesting thermal and mechanical properties to cementitious ...materials. However, its effects on geopolymeric matrices remain poorly understood, although it can improve the matrix. In this work, the effect of incorporating 0.10%, 0.20%, and 0.50% (wt) of silicon carbide microwhiskers (SCMW) into a metakaolin-based geopolymer matrix was studied. The rotational rheology, mechanical properties, and thermal behavior were evaluated using isothermal calorimetry and thermogravimetric analysis. The results showed that the SCMW modified the rheological parameters of the geopolymer, increasing the viscosity at higher content and slightly modifying the velocity of the reaction. Meanwhile, the composite with 0.20% SCMW content showed better mechanical performance after 28 days, although the composite with 0.50% SCMW content had a similar or higher increase in mechanical performance after 24 h, comparing compressive and flexural strength respectively. However, these results are because of the SCMW properties rather than any new phases formed.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
To characterize dynamic changes of arteriovenous malformation using a microscope-integrated technique at the moment of performing intraoperative fluorescein videoangiography (FL-VAG) at each of the ...resection phases.
We prospectively recruited 12 patients with arteriovenous malformations and used FL-VAG as an ancillary technique for resection of the lesion. We analyzed transit time (TT) of FL in arterial feeders (arterial transit time TTa) and draining veins (venous transit time TTv) during the different stages of resection. To achieve this, we recorded 3 values of TT of FL (TTa, initial TTv, final TTv); when final TTv was markedly slower than initial TTv, we hypothesized that the nidus was devascularized enough and could be safely removed.
No mortality or morbidity was related to use of FL. In most cases, TT values of arterial feeders and draining veins allowed an easier distinction between them. At advanced stages of resection, FL-VAG assessed increase in TTv (venous blood slower or absent), suggesting that most feeding arteries had been obliterated, indicating the appropriate moment for nidus removal. Optimal dose of FL was a 75-mg bolus followed by injection of 20 mL of saline solution.
FL-VAG allows a distinction of normal from abnormal flow in draining vessels and might help the surgeon to decide when the nidus can be safely removed. This is the first study prospectively evaluating this technique, and it proposes an ideal dose for brain arteriovenous malformation surgery, in contrast to doses used in tumor cases.
•FL-VAG can be helpful in microsurgery of cortical AVMs.•FL-VAG aids the neurosurgeon to make decisions during the procedure and allows complete resection of the nidus.•In deep AVMs, the benefit of FL-VAG remains to be established.•The optimal dose of sodium fluorescein was a 75-mg bolus repeated as necessary.•FL-VAG provides a visual guide to identify feeders and main draining vein in cases with multiple veins.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
PDF
