Flotation of Iron Ores: A Review Zhang, Xiaolong; Gu, Xiaotian; Han, Yuexin ...
Mineral processing and extractive metallurgy review,
04/2021, Letnik:
42, Številka:
3
Journal Article
Recenzirano
A tremendous amount of research has been done on refining the flotation process for iron ore and designing the reagents which go into it. This paper reviews the industrial practices and fundamental ...research surrounding iron ore flotation. The advantages and disadvantages of direct flotation, cationic reverse flotation, and anionic reverse flotation are reviewed. A novel stepped flotation technique is discussed for the treatment of carbonate-rich iron ores. The necessity of desliming to enable effective flotation is discussed in detail. Selective flocculation desliming is discussed in particular detail as it is the primary deslime methodology used in industry. This paper also describes a large variety of reagents commonly used or in development in each flotation route, covering collectors, activators, depressants, dispersants, flocculants, and frothers. The impact of the zeta potential and surface chemistry on flotation and deslime is also discussed. The aim of this paper is to provide a well-detailed, well-referenced source for the current status of iron ore flotation, and thus provide a useful guide to its future development and to further improve flotation performance for iron ore.
•Trypanosome clones maintain the infectivity and virulence of the original strains in mice experimental infections.•T. equiperdum develop higher parasitemia than T. evansi in a short period of time ...in mice model.•T. equiperdum caused anemia but do not show the classical Dourine clinical signs since 100% of them died in 8 days.
Livestock trypanosomoses, caused by three species of the Trypanozoon subgenus, Trypanosoma brucei brucei, T. evansi and T. equiperdum are widely distributed and limit animal production throughout the world. The infectivity and virulence of clones derived from Trypanosoma evansi and Trypanosoma equiperdum Venezuelan strains were compared in an in vivo mouse model. Primary infectivity and virulence determinants such as survival rates, parasitemia levels, PCV, and changes in body weight and survival rates were monitored for up to 32 days. The T. equiperdum strain was the most virulent, with 100% mortality in mice, with the highest parasitemia levels (7.0 × 107 Tryps/ml) and loss of physical condition. The T. evansi strains induced 100% and 20% fatality in mice. Our results show that the homogeneous parasite populations maintain the virulent phenotype of the original T. equiperdum and T. evansi stocks. This is the first comparative study of infectivity and virulence determinants among clonal populations of T. equiperdum and T. evansi.
Introduction
The ketogenic diet (KD) is increasingly used for the treatment of refractory epilepsy. The aim of this study was to evaluate possible adverse effects of the diet on cognition, behavior, ...psychosocial adjustment, and quality of life in school‐aged children and adolescents.
Method
Fifteen subjects were assessed before diet initiation. After approximately 6 months, on diet treatment 11 patients (73%) were reassessed. We used a combination of individually administered psychological tests for the children and parent report questionnaires.
Results
Five of 15 patients had a seizure reduction of more than 50%. Cognition showed a small trend toward improvement in most patients. Psychosocial adjustment, on the other hand, showed small trends toward worsening. For mood, two areas showed a larger change, revealing more mood problems although this was not on a statistically significant level.
Conclusion
In this small group of children, there is no indication that the KD has a negative impact on cognition or social adaptation at short term. There is a tendency toward an increase in mood problems.
Mapping of glycine distributions in gliomas Maudsley, A A; Gupta, R K; Stoyanova, R ...
American journal of neuroradiology : AJNR,
06/2014, Letnik:
35, Številka:
6 Suppl
Journal Article
Recenzirano
Odprti dostop
Increased glycine concentration in the brain is associated with altered metabolism in cancer and can be detected by using in vivo MR spectroscopy. This has been proposed as a marker for grade IV ...gliomas; however, little is known about the potential significance and frequency of in vivo glycine observation. The purpose of this study was to examine the rate of occurrence and spatial distribution of glycine observation with respect to other MR imaging parameters.
Data from volumetric whole-brain MR spectroscopic imaging of 59 subjects with glioma were analyzed with glycine included in the spectral model. The associations of the signal amplitude and spatial distributions of glycine with findings from contrast-enhanced T1, perfusion, and diffusion MR imaging were then examined.
Glycine was detected in 24% of all studies, though with a wide range of signal amplitude and extent of the spatial distributions. While more commonly seen in grade IV tumors (42% of studies), relatively large concentrations were also detected in grade II and III gliomas. Coanalysis with other metabolites indicated a strong association with choline and that glycine was frequently seen to be overlapping with, and adjacent to, areas of high lactate concentration. Increased glycine was always associated with contrast enhancement and areas of increased cerebral blood flow, but without any clear association with other image parameters.
Detection of increased glycine in gliomas appears to identify a subgroup of tumors and areas of increased proliferation.
Prostate cancer diagnosis and treatment continues to be a major public health challenge. The heterogeneity of the disease is one of the major factors leading to imprecise diagnosis and suboptimal ...disease management. The improved resolution of functional multi-parametric magnetic resonance imaging (mpMRI) has shown promise to improve detection and characterization of the disease. Regions that subdivide the tumor based on Dynamic Contrast Enhancement (DCE) of mpMRI are referred to as
in this study. The DCE defined perfusion curve patterns on the identified tumor habitat region are used to assess clinical significance. These perfusion curves were systematically quantified using seven features in association with the patient biopsy outcome and classifier models were built to find the best discriminating characteristics between clinically significant and insignificant prostate lesions defined by Gleason score (GS). Multivariable analysis was performed independently on one institution and validated on the other, using a multi-parametric feature model, based on DCE characteristics and ADC features. The models had an intra institution Area under the Receiver Operating Characteristic (AUC) of 0.82. Trained on Institution I and validated on the cohort from Institution II, the AUC was also 0.82 (sensitivity 0.68, specificity 0.95).
Although extensive research has been conducted on the effect of water chemistry in flotation, no single study exists which describes the effect of calcium and magnesium on the adsorption of starch ...onto the hematite in iron ore flotation. In this work flotation, entrainment, zeta potential, and settling tests were performed to determine the differing impact of calcium and magnesium in iron ore flotation. Results showed that magnesium is more detrimental to the flotation process at far lower concentrations than calcium. Performing flotation with 45 ppm of calcium resulted in a comparable impact on the process as performing flotation with 7 ppm of magnesium. While calcium promotes the adsorption of starch onto the hematite and reduces entrainment, past an optimal dosage magnesium is promoting the adsorption of starch to everything in solution causing low grades and recoveries. It was found that the starch adsorption onto the hematite is strongly impacted by the presence of magnesium, suggesting that starch is collecting the magnesium and self-flocculating prior to adsorption onto the hematite. Thus, the presence of magnesium can significantly reduce the flotation performance far more than what would be expected from calcium.
Inflammatory bowel disease (IBD) is a chronic disease that requires chronic treatment throughout the evolution of the disease, with a complex physiopathology that entails great challenges for the ...development of new and specific treatments for ulcerative colitis and Crohn´s disease. The anti-tumor necrosis factor alpha therapy has impacted the clinical course of IBD in those patients who do not respond to conventional treatment, so there is a need to develop new therapies and markers of treatment response. Various pathways involved in the development of the disease are known and the new therapies have focused on blocking the inflammatory process at the gastrointestinal level by oral, intravenous, subcutaneous, and topical route. All these new therapies can lead to more personalized treatments with higher success rates and fewer relapses. These treatments have not only focused on clinical remission, but also on achieving macroscopic changes at the endoscopic level and microscopic changes by achieving mucosal healing. These treatments are mainly based on modifying signaling pathways, by blocking receptors or ligands, reducing cell migration and maintaining the integrity of the epithelial barrier. Therefore, this review presents the efficacy and safety of the new treatments that are currently under study and the advances that have been made in this area in recent years.
Magnetic resonance (MR) imaging and computed tomography (CT) are used almost exclusively in radiation therapy planning of glioblastoma multiforme (GBM), despite their well-recognized limitations. MR ...spectroscopic imaging (MRSI) can identify biochemical patterns associated with normal brain and tumor, predominantly by observation of choline (Cho) and N-acetylaspartate (NAA) distributions. In this study, volumetric 3-dimensional MRSI was used to map these compounds over a wide region of the brain and to evaluate metabolite-defined treatment targets (metabolic tumor volumes MTV).
Volumetric MRSI with effective voxel size of ∼1.0 mL and standard clinical MR images were obtained from 19 GBM patients. Gross tumor volumes and edema were manually outlined, and clinical target volumes (CTVs) receiving 46 and 60 Gy were defined (CTV46 and CTV60, respectively). MTVCho and MTVNAA were constructed based on volumes with high Cho and low NAA relative to values estimated from normal-appearing tissue.
The MRSI coverage of the brain was between 70% and 76%. The MTVNAA were almost entirely contained within the edema, and the correlation between the 2 volumes was significant (r=0.68, P=.001). In contrast, a considerable fraction of MTVCho was outside of the edema (median, 33%) and for some patients it was also outside of the CTV46 and CTV60. These untreated volumes were greater than 10% for 7 patients (37%) in the study, and on average more than one-third (34.3%) of the MTVCho for these patients were outside of CTV60.
This study demonstrates the potential usefulness of whole-brain MRSI for radiation therapy planning of GBM and revealed that areas of metabolically active tumor are not covered by standard RT volumes. The described integration of MTV into the RT system will pave the way to future clinical trials investigating outcomes in patients treated based on metabolic information.
Abstract Frequent interictal epileptiform discharges (IEDs) may have effects on cognition. We analysed a group of 182 children with different epilepsy syndromes, all of whom had IEDs that did not ...result in observed seizures, with 24-h ambulatory EEG and cognitive tests. The IED index was estimated, in wakefulness and in sleep, as percentage of time in five categories (0%, <1%, 1–10%, ≥10–50% and ≥50%). IEDs were defined as spikes or spike–wave complexes, isolated or occurring serially (in runs) without evident clinical signs of a seizure. The IED categories were correlated to cognitive test results and epilepsy characteristics. The group of patients with diurnal IEDs in ≥10% of the EEG record showed impaired central information processing speed, short-term verbal memory and visual-motor integration. This effect was seen independently from other EEG-related and epilepsy-related characteristics, and independently from epilepsy syndrome diagnosis. The impact of the nocturnal IEDs was of less importance; only contributing partially to the slowing of central information processing speed. We conclude that frequent IEDs (in more than 10% of the record) in the awake EEG can impair cognitive performance in children. Whether children with a high diurnal spike frequency and low seizure frequency can benefit from antiepileptic treatment should be examined in controlled trials.
The vascular endothelial growth factor (VEGF) is an essential factor to pathologic angiogenesis. Disruption of VEGF/VEGF receptor interaction in cancer patients inhibits the development of new and ...pre-existing tumor blood vessels. Consequently, VEGF becomes an important therapeutic target for handling solid tumors. In this work, human VEGF was produced in the culture supernatant of SiHa cells transduced with a replication-defective adenoviral vector (pAdhVEGF
121
) encoding this molecule. The 35 kDa VEGF
121
homodimer was obtained from clarified culture media as a glycosylated protein. VEGF
121
expression levels were strictly dependent on the adenoviral viral load used. VEGF
121
was produced with purity over 98% after a single step chromatography by immobilized metal affinity chromatography. Additionally, VEGF
121
binds Bevacizumab antibody with a K
D
of 7 nM. Biological characterization by mitogenic assay in HUVEC and ECV-304 cells showed that VEGF
121
stimulates cell proliferation in a dose-dependent manner in both cells. Finally, the neovascularization activity of VEGF
121
was demonstrated by vascular permeability assays in matrigel plug-bearing mice, showing significantly increased vasculature leakage after treatment with VEGF
121
. Consequently, transduction of SiHa cells with adenovirus is a suitable alternative for manufacture heterologous proteins of therapeutic interest.
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