Objectives
We compared pure molecular diffusion (
D
), perfusion-related diffusion (
D
*), perfusion fraction (
f
) and apparent diffusion coefficient (ADC) based on intravoxel incoherent motion ...(IVIM) theory in patients with nasopharyngeal carcinoma (NPC).
Methods
Sixty-five consecutive patients (48 men) with suspected NPC were examined using a 3.0-T MR system. Diffusion-weighted imaging (DWI) was performed with 13
b
values (range, 0–800 s/mm
2
). We regarded the result of endoscopy and biopsy as the gold standard for detection.
D
,
D
* and
f
were compared between patients with primary NPC and enlarged adenoids.
Results
IVIM DWI was successful in 37 of 40 NPC and 23 of 25 enlarged adenoids cases.
D
(
P
= 0.001) and
f
(
P
< 0.0001) were significantly lower in patients with NPC than in patients with enlarged adenoids, whereas
D
* was significantly higher (
P
< 0.0001). However, the ADC was not significantly different between the two groups (
P
> 0.05). The area under the ROC curve (AUC) for
D
was 0.849 and was significantly larger than that for ADC (
P
< 0.05).
Conclusions
IVIM DWI is a feasible technique for investigating primary NPC.
D
was significantly decreased in primary NPC, and increased
D
* reflected increased blood vessel generation and parenchymal perfusion in primary NPC.
Key Points
•
Intravoxel incoherent motion
(
IVIM
)
analysis permits separate quantification of diffusion and perfusion
.
•
IVIM DWI is a feasible technique for investigating primary NPC
.
•
IVIM suggests that primary NPC tissue voxels exhibit both perfusion and diffusion
.
Edible films from chitosan, cassava starch, and gelatin plasticized with glycerol have been developed by casting method, and the effects of cassava starch (50, 100 and 150 g per 100 g of chitosan), ...gelatin (0, 25 and 50 g per 100 g of chitosan) and glycerol (21, 42 and 63 g per 100 g of chitosan) from the film solution on various properties of chitosan-based films have been studied using response surface methodology (RSM). The possible interactions between the major components were evaluated by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The properties of the resulting chitosan-based blends for films were greatly influenced by the incorporation of cassava starch, gelatin and glycerol. The introduction of gelatin and gelatinized cassava starch suppressed the semicrystalline peaks of chitosan films. The amino peak of gelatin shifted from 1542 to 1559 cm-1, and the NH and/or OH peak of gelatin, cassava starch and chitosan films shifted from 3384, 3414 and 3421, respectively, to 3422 cm-1 in the composite film. These results indicate that there was an interaction and molecular miscibility among the major components. The growth inhibition of phytopathogen on mango fruit surface indicated the efficiency of these coatings and they can be applied for the conservation of fresh or minimally processed fruits and vegetables.
Machining, especially dry machining of titanium alloys, has been one of the most significant challenges for carbide cutting tools. In this study, aluminum-rich AlTiN coating, as well as TiAlSiN ...nanocomposite coating, were successfully employed for dry milling of Ti–6Al–4V alloy with high efficiency and long tool life. At the cutting speeds of 150 m/min and 200 m/min, the tool life of the TiAlSiN-coated tool exceeds that of AlTiN-coated tool by 32 and 66%, respectively. The wear modes for both coated tools include the uniform flank wear, smooth wear, chipping, coating and substrate flaking, crater and notch wear, and the wear mechanisms include adhesion, diffusion, oxidation and crack. Among them, the wear mechanism is dominated by the adhesion and oxidation wear. As compared with AlTiN coating, TiAlSiN coating exhibits better mechanical properties and oxidation resistance, which contribute to a better cutting performance, fewer thermal cracks and smaller and uniform workpiece chips during the dry milling of Ti–6Al–4V alloy.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Comparisons on the bioleaching and sterile oxidation of pyrite were performed at controlled redox potential of 900 mV (vs. SHE) and different temperatures of 30 and 60 °C. For sterile experiments, ...the redox potential of irrigation solution was controlled by adding hydrogen peroxide solution (15 wt%), while the redox potential of irrigation solution for bioleaching was elevated by flowing through the packed bed in which bacteria were activated and colonized. The rate of pyrite bioleaching is faster than that of sterile oxidation at temperature of 30 °C. The reason is that the potential gradient of leaching solution in bioleaching column is much smaller than that in sterile column. The redox potentials of irrigation solution and leaching solution are similar for bioleaching; however, the redox potential difference of irrigation solution and leaching solution for sterile oxidation is about 150 mV. When temperature increases to 60 °C for sterile oxidation, the rate of pyrite leaching is faster than that of bioleaching at temperature of 30 °C, even though the redox potential gradient of leaching solution is great. The mineralogy analyses of pyrite residue were performed by scanning electron microscopy–energy-dispersive spectroscopy (SEM–EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses. The results confirm that pyrite oxidation might only occur at specific sites with high surface energy on surface and obeys the “indirect mechanism” whether there are bacteria or not. The pyrite oxidation rate is not inhibited by inert sulfur on residue surface at elevated redox potential. According to the conclusions, the way to accelerate pyrite oxidation is proposed.
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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
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•Thiourea leaching with mechanical activation was proposed to extract gold from calcine.•The addition of CMN can effectively prevent the passivation by sulfur and the agglomeration of ...particles.•The mechanism of CMN and mechanical activation is revealed.•This process proposed in this work can efficiently and cleanly extract gold.•This process has a potential application in industry.
Non-cyanide gold leaching serves as a promising green approach for eliminating cyanide utilization and the resulting environmental pollution from cyanide use. In this work, thiourea leaching combined with mechanical activation was employed to extract gold from a refractory gold concentrate calcine. The optimal reaction conditions were determined as: 2.5 g/L thiourea, 2 g/L Fe3+, 0.6 g/L CMN, 45 Hz input frequency, liquid to solid ratio (L/S) of 4, temperature of 40 °C, and leaching time of 55 min. Addition of sodium lignosulfonate increased gold extraction from 93.6% to 96.5%. Mechanical activation proved to be a promising method to reduce the particle size of minerals, which effectively increases the specific surface area and pore diameter of minerals and thus strengthens the leaching reaction. Furthermore, CMN is capable of preventing particle agglomeration and the coating by a sulfur passivation layer, which enhances gold extraction efficiency. Additionally, a pilot-scale test was conducted to validate the reliability of this novel technique. The pilot-scale tests proved this method to be an efficient process for gold extraction with opportunities for scaling up.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
To design heap biooxidation process, it is necessary to understand its internal rules. The heap biooxidation of gold ore from Anhui province was researched in this study. The results showed that the ...main microorganisms in the heap were
A. ferrooxidans
,
F. acidiphilum
and
L. ferrodiazotrophum
. Under their combined action, gold leaching extent rose from 35.62% to 78.08% in 80 d. Boltzmann model matches the actual oxidation effect better and the model equations were obtained. The model predicted that the oxidation extents of arsenic and sulfur are 58.577% and 42.122% after one year, and the gold leaching extent was 80.40%. The arsenic and sulfur oxidation extents, and gold leaching extent were all linearly correlated. It is more reliable to predict gold leaching extent by sulfur oxidation extent. These results provided good guidance for practical application in the actual production.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Cyanide Tailings (CTs) are known as hazardous resources that accumulate hundreds of millions of tons, threatening the ecological environment. This work proposes an eco-friendly and efficient way to ...recover gold, iron, and silicon from CTs. By controlling the reduction atmosphere and temperature in the reduction roasting process, >99% of cyanide could be selectively removed, and 65.3% of the encapsulated gold in iron oxide and sulfide could also be released. The reduction of particle size by mechanical activation liberated 92.3% of gold encapsulated in silicate and iron oxide minerals which increased the extraction efficiency of gold in non-cyanide leaching process to 94.5%. The grade and recovery of iron concentrate obtained from the magnetic separation reached 60.9% and 74.6%, respectively, by regulating the magnetic field intensity of 70 kA/m. While the iron concentrate could be directly traded, the tailings of Si grade 28.4% (w/w) could be used in building materials. The proposed technology can realize the harmless resource utilization of the hazardous CTs with the potential for promising industrial applications.
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•An eco-friendly approach for efficient recovery of gold, iron and silicon from CTs was proposed.•Thermodynamics, mineralogical characteristics and mechanism in the process is clarified.•The leaching efficiency of gold in non-cyanide system reached 94.5%.•The iron grade and recovery of the magnetically separated concentrate reached 60.9% and 74.6%.•This technology has the potential for industrial applications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Most of the gold is encapsulated in sulfides and arsenopyrite in Carlin type gold concentrate; the gold leaching efficiency is less than 8% without pretreatment. Cyanide process is a traditional gold ...leaching method with the disadvantages of several environmental pollution incidents occurred due the breach of tailings disposal. In view of the difficulties in gold extraction and serious pollution incidents of typical Carlin type gold concentrate, this paper proposes pressurized oxidation - sodium jarosite decomposition - polysulfide leaching method to recover gold from typical Carlin type gold concentrate. Standard characterization/analytical methods of XRD, ICP, MLA, XPS, and SEM-EDS were employed in the experiment. In the pressurized oxidation pretreatment process with high temperature and ferric sulfate concentration, jarosite minerals with stable properties were easily formed due to the appropriate amounts of K+ introduced in the flotation of the ore and a small amount of mica minerals containing Na+. The results show that pressurized oxidation pretreatment can efficiently liberate gold from the mineral, but causes secondary inclusion of sodium jarosite. The one-step sodium jarosite decomposition treatment of the residue produced by oxygen pressure leach, can effectively liberate gold from the sodium jarosite pHase. Thus, the influence of factors on extracting gold from sodium jarosite decomposition residue using polysulfide were systematically studied. Under the most suitable conditions, the leaching efficiency of gold increased up to 90.2%, which was 8.4% higher than that of the direct cyanidation of oxygen pressure leach residue. This study provides an efficient, clean, and environmentally friendly way for the resource utilization of refractory gold concentrate, with a potential industrial application.
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•Pressure oxidation pretreatment - sodium jarosite decomposing - polysulfide leaching was proposed;•The mechanism of mineral phase change in the pretreatment process is clarified;•The leaching efficiency of gold in polysulfide system reached 90.2%;•The XPS analysis was carried out to analyze the valence state of sulfur on the surface of the leaching residue.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
High-efficiency recovery of Zn and Pb from silicon-rich zinc leaching residues is realized in a rotary kiln. Characterizations by means of XRD, SEM, EDS and ICP reveal that the leaching residue ...contains 12.4 wt.% SiO2, 16.1 wt.% Zn, and 7.4 wt.% Pb. Thermodynamic analysis shows that metallic vapor of Zn and Pb can be easily generated from the zinc leaching residue at 1150−1250 °C inside the rotary kiln. Viscosities and melting points of 13 slag compositions were analyzed and three slag compositions (47wt.%SiO2−23wt.%CaO−30wt.%FeO, 40wt.%SiO2− 28wt.%CaO−32wt.%FeO, and 40wt.%SiO2−30wt.%CaO−30wt.%FeO) possessed the desirable physical properties, with the melting point and viscosity in the range of 1150−1280 °C and 0.2−0.5 Pa·s, respectively. The industrial tests show that adopting the optimized slag composition can contribute to very high recovery rates of Zn and Pb (97.3% for Zn and 94.5% for Pb), corresponding to slags with very low average contents of Zn and Pb (0.51 wt.% Zn and 0.45 wt.% Pb). The National-Standard leaching tests of the water-quenched slags result in 1.82 mg/L Zn, ~0.01 mg/L Cu, 0.0004 mg/L As, ~0.01 mg/L Cd, 0.08 mg/L Pb, and ~0.02 mg/L Hg in the leachate, verifying the detoxification of the zinc leaching residue at the same time.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Gold bearing pyrite leaching was conducted in H2SO4–Fe2(SO4)3 system at different reaction temperatures, with different ferric ion concentrations, sulfuric acid concentrations and stirring speeds. ...The leaching kinetics and mechanism were studied. When the temperature ranged between 30–75 °C, the pyrite leaching was mainly controlled by chemical reaction with positive correlation to the ferric ion concentration. The activation energy obtained from Arrhenius empirical formula is 51.39 kJ/mol. The EDS and XPS analyses suggest that the oxidation of sulfur within pyrite is through a series of intermediate stages, and eventually is oxidized to sulphate accompanied with the formation of element sulfur. This indicates a thiosulfate oxidation pathway of the gold bearing pyrite oxidation in H2SO4–Fe2(SO4)3 system.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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