Investigation on the application of by-product steam in iron ore sintering: performance and function mechanism.

The combustion-supporting effect of steam to coke breeze in sintering has the potential to improve sinter quality and reduce pollutants emissions. The results show that increasing the by-product steam injection concentration (0.32-0.47vol%) and prolonging the injection time (5 min) within a proper range (10-15 min) can improve sinter quality. 2.13kgce/t-sinter of the fuel consumption was decreased by reducing coke breeze usage from 5.60 to 5.45% under the recommended parameters, with 15.16% decrease of CO in sintering waste gas. By comparing experimental data with thermodynamic calculations, although the reaction between CO and steam can reduce CO emission and generate H2, steam tends to react with coke breeze to generate H2 and CO (react at 674℃), and OH radical produced by H2 which can reduce the activation energy of CO oxidation reaction is the key to reducing pollutant emissions. The potential economic benefit of steam injection technology was calculated based on a 360m2 sintering machine (the annual sinter output is 3.2million tons), excluding the equipment modification and steam injection cost of $300,000; a profit of $737491.2 per year or 0.23 dollars per ton sinter can be achieved. Therefore, low-carbon and cleaner iron ore sintering production can be realized through applying by-product steam.

A novel multifunctional nanoparticles formed by molecular recognition between AS1411 aptamer and redox-responsive paclitaxel-nucleoside analogue prodrug for combination treatment of ß-lapachone and paclitaxel.

Despite its high antitumor activity, the clinical application of chemotherapy is greatly impeded by lacking of specific accumulation and poor solubility. To address the above challenges, we designed a AS1411 aptamer modified nanoparticles based on molecular recognition of nucleobases. Firstly, a redox sensitive Paclitaxel-SS-Zidovudine (PZ) prodrug was synthesized. Then PZ/ß-lapachone/AS1411/DSPE-PEG nanoparticles were prepared and AS1411 aptamer was connected through molecular recognition between the nucleoside analogue Zidovudine (ZDV) and the thymine on aptamer. DSPE-PEG (DP) was incorporated into nanoparticles to prolong the residence time of nanoparticles in the blood circulation. Furthermore, to realize the combination treatment, ß-lapachone (LAP) has been incorporated into nanoparticles with high drug loading efficiency through the interaction of π-π stacking force and H-bonding between LAP and Paclitaxel (PTX). LAP can generate abundant exogenous reactive oxygen species (ROS) via the bioactivation of NAD(P)H: quinone oxidoreductase-1 (NQO1). Moreover, the connection of Zidovudine (ZDV) and AS1411 through molecular recognition of nucleobases further optimized the nanoparticles with high affinity to nucleolin which overexpressed on tumor cell membrane, thereby inducing the specific accumulation of nanoparticles in tumor sites. In vivo and in vitro studies showed that the obtained nanoparticles of PZ/LAP/AS1411/DP exhibited better tumor growth inhibition and lower systemic side effects. Herein, we have rationally conducted a novel self-codelivery system for effectively synergistic antitumor treatment.

Redox-responsive nanoparticles based on Chondroitin Sulfate and Docetaxel prodrug for tumor targeted delivery of Docetaxel.

In this paper, a novel redox-responsive nanoparticles has been designed for targeted delivery of docetaxel (DTX). Chondroitin sulfate (CS) was used to construct the nanoparticles due to the ability of tumor targeting through binding with CD44 receptor that overexpresses on the surfaces of various tumor cells. A redox-responsive small-molecular DTX prodrug was prepared through modifying with cystamine containing disulfide bonds (Cys-DTX). Then the DTX prodrug was grafted to the CS to construct the amphiphilic polymer (CS-ss-DTX). Further, Cys-DTX/CS-ss-DTX nanoparticles were formed by self-assembly of amphiphilic polymer and incorporation of free Cys-DTX prodrug. This category of nanosized DTX delivery system was expected for not only exhibiting high permeability and cytotoxicity of Cys-DTX prodrug, but also targeting transportation of encapsulated redox-responsive Cys-DTX prodrug. According to results of related researches on physicochemical properties and biological evaluation, the novel redox-responsive Cys-DTX/CS-ss-DTX nanoparticles increased amount of DTX released from the nanoparticles in reductive environment, improved permeability in tumor tissues, enhanced cytotoxicity and decreased side effects compared with free DTX. All of these results showed that this kind of Cys-DTX/CS-ss-DTX nanoparticles were worthy of being expectation in tumor chemotherapy in future.

Redox- and MMP-2-sensitive drug delivery nanoparticles based on gelatin and albumin for tumor targeted delivery of paclitaxel.

Tumor-responsive nanocarriers are highly valuable and demanded for smart anticancer drug delivery, where a quick release of chemotherapeutic drugs in tumors is preferred. Herein, a redox and MMP-2 sensitive nanoparticle has been designed for targeted delivery of PTX. Bovine serum albumin as a targeting ligand and gelatin as a hydrophilic carrier and MMP-2 sensitive reagent were used to construct the nanoparticles. Disulfide containing prodrug (PTX-SS-COOH) was grafted to the sulfhydryl modified gelatin to form the redox sensitive amphiphilic polymer. The nanoparticles were formed by self-assembly of amphiphilic polymer and BSA covering. Furthermore the modified sulfhydryl group on the gelatin can form a disulfide bond by self-crosslinking in the air, which endows the nanoparticle with a stable structure. The nanoparticle was sensitive to changes in MMP-2 concentration and redox potential, resulting in multiple responsive drug delivery to the tumor microenvironment. We further verified the anticancer effect of the nanoparticles both in vitro and in vivo, the nanoparticle (BSA/Gel-SS-PTX/PTX-SS-COOH NPs) demonstrated an excellent anticancer efficiency.

Positive relationship of hypertensive retinopathy with carotid intima--media thickness in hypertensive patients.

OBJECTIVES: We aimed to explore the relationship of hypertensive retinopathy with carotid intima--media thickness (CIMT), and to examine the possible effect modifiers in Chinese adults with hypertension. METHODS: We conducted a cross-sectional study of 12 342 hypertensive patients with complete exit site visit data from the China Stroke Primary Prevention Trial. CIMT was measured by carotid ultrasonography. Hypertensive retinopathy was diagnosed according to the Keith--Wagener--Barker classification. RESULTS: The mean (SD) CIMT among study participants was 739.9 (111.4) µm. Compared with patients with grade 1 hypertensive retinopathy or without hypertensive retinopathy, a significantly higher CIMT level (ß, 7.63, 95% CI: 2.54--12.73) was observed in patients with grade 2-4 hypertensive retinopathy. Moreover, the association between hypertensive retinopathy (grade 2-4 versus grade 1 or normal) and CIMT was stronger in participants of younger age (<60 years; ß, 13.70, 95% CI: 5.65--21.75; versus ≥60 years; ß, 1.03, 95% CI: -5.58 to 7.63; P interaction = 0.006); or with lower total homocysteine levels [<12.1 µmol/l (median); ß, 12.70, 95% CI: 5.98--19.42; versus ≥12.1 µmol/l; ß, 2.07, 95% CI: -5.63 to 9.78; P interaction = 0.030). None of the other variables, including sex, BMI, study centers, treatment group, SBP, triglycerides, total cholesterol, fasting blood glucose, folate, serum creatinine, current smoking and alcohol drinking, significantly modified the relation of hypertensive retinopathy with CIMT levels. CONCLUSION: Hypertensive retinopathy (grade 2 and higher) was significantly associated with increased CIMT in hypertensive patients. The association was stronger in those of younger age or with lower total homocysteine levels.

FBXO31 modulates activation of hepatic stellate cells and liver fibrogenesis by promoting ubiquitination of Smad7.

Liver fibrosis is a critical pathological process in the early stage of many liver diseases, including hepatic cirrhosis and liver cancer. However, the molecular mechanism is not fully revealed. In this study, we investigated the role of F-box protein 31 (FBXO31) in liver fibrosis. We found FBXO31 upregulated in carbon tetrachloride (CCl4 ) induced liver fibrosis and in activated hepatic stellate cells, induced by transforming growth factor-ß (TGF-ß). The enforced expression of FBXO31 caused enhanced proliferation and increased expression of α-smooth muscle actin (α-SMA) and Col-1 in HSC-T6 cells. Conversely, suppression of FBXO31 resulted in inhibition of proliferation and decreased accumulation of α-SMA and Col-1 in HSC-T6 cells. In addition, upregulation of FBXO31 in HSC-T6 cells decreased accumulation of Smad7, the negative regulator of the TGF-ß/smad signaling pathway, and suppression of the FBXO31 increased accumulation of Smad7. Immunofluorescence staining showed FBXO31 colocalized with Smad7 in HSC-T6 cells and in liver tissues of BALB/c mice treated with CCl4 . Immunoprecipitation demonstrated FBXO31 interacted with Smad7. Moreover, FBXO31 enhanced ubiquitination of Smad7. In conclusion, FBXO31 modulates activation of HSCs and liver fibrogenesis by promoting ubiquitination of Smad7.

Influences of fine-grained NaCl particles on performance and denitration efficiency of activated carbon during sintering flue gas purification process.

Alkali metal chlorides emitted from sintering flue gas are easily adsorbed on the surface of activated carbon (AC) in the purification process. In this paper, NaCl particles adsorbing onto AC were simulated by impregnation method, and the size and morphology of NaCl particles were similar to those of NaCl-PM10 emitted from sintering flue gas. With the adsorption of NaCl particles, 2-10-µm pores of AC were filled, and the specific surface area of AC decreased. But NaCl led to the increase of acidic functional groups on the surface of AC. When 0.75 wt% NaCl was adsorbed, it was beneficial for AC catalytic denitration (de-NOx), because the chemical reaction was strengthened by acidic functional groups, so it showed a certain promotion of de-NOx efficiency. As 1.5 wt% NaCl and 3 wt% NaCl were adsorbed, NaCl had an inhibitory effect on AC de-NOx, which was because the specific surface area of AC decreased, and the prevention of physical adsorption played a major role. As a result, the de-NOx efficiency of AC adsorbed with 3 wt% NaCl decreased from 40.59 to 23.02% at 150 °C. Therefore, the absorption of NaCl fine particles on AC should not exceed 0.75 wt%.

Clean recycle and utilization of hazardous iron-bearing waste in iron ore sintering process.

Applying recycled iron-bearing waste materials (RIM) into iron ore sintering process is the general disposal approach worldwide, while its use is still a thorny problem. Results showed that adding RIM increased contents of hazardous elements (K, Na, Pb, Zn, and Cl) in sinter product, and also enhanced emission concentration of PM2.5 in flue gas; increasing reaction temperature, and contents of CaO & coke breeze in raw mixtures improved hazardous elements removal. Based on these features, a novel method through granulating natural iron ores and RIM separately and distributing granulated RIM in bottom sintering layers was proposed for clean RIM cycle. When recycling 5% RIM, granulating RIM separately with higher contents of CaO and coke breeze removed hazardous elements effectively, the contents of which in sinter were reduced to comparable level of the case without RIM. Moreover, distributing RIM in bottom sintering layer reached intensive release of hazardous elements and PM2.5 during sintering, which reduced the flue gas volume needing purification by about 2/3. Through activated carbon purification, about 60% of PM2.5 comprised high contents of hazardous elements was removed. Novel technique eliminated the negative impact of RIM and has the prospect to reach clean recycle in sinter-making plants.

Influence of sulfur dioxide-related interactions on PM2.5 formation in iron ore sintering.

The formation of PM2.5 (aerosol particulate matter less than 2.5 µm in aerodynamic diameter) in association with SO2 emission during sintering process has been studied by dividing the whole sintering process into six typical sampling stages. A low-pressure cascade impactor was used to collect PM2.5 by automatically segregating particulates into six sizes. It was found that strong correlation existed between the emission properties of PM2.5 and SO2. Wet mixture layer (overwetted layer and raw mixture layer) had the function to simultaneously capture SO2 and PM2.5 during the early sintering stages, and released them back into flue gas mainly in the flue gas temperature-rising period. CaSO4 crystals constituted the main SO2-related PM2.5 during the disappearing process of overwetted layer, which was able to form perfect individual crystals or to form particles with complex chemical compositions. Besides the existence of individual CaSO4 crystals, mixed crystals of K2SO4-CaSO4 in PM2.5 were also found during the first half of the temperature-rising period of flue gas. The interaction between fine-grained Ca-based fluxes, potassium vapors, and SO2 was the potential source of SO2-related PM2.5. IMPLICATIONS: The emission property of PM2.5 and SO2 throughout the sintering process exhibited well similarity. This phenomenon tightened the relationship between the formation of PM2.5 and the emission of SO2. Through revealing the properties of SO2-related PM2.5 during sintering process, the potential interaction between fine-grained Ca-based fluxes, potassium vapors, and SO2 was found to be the source of SO2-related PM2.5. This information can serve as the guidance to develop efficient techniques to control the formation and emission of PM2.5 in practical sintering plants.

Reaction behavior of SO2 in the sintering process with flue gas recirculation.

UNLABELLED: The primary goal of this paper is to reveal the reaction behavior of SO2 in the sinter zone, combustion zone, drying-preheating zone, and over-wet zone during flue gas recirculation (FGR) technique. The results showed that SO2 retention in the sinter zone was associated with free-CaO in the form of CaSO3/CaSO4, and the SO2 adsorption reached a maximum under 900ºC. SO2 in the flue gas came almost from the combustion zone. One reaction behavior was the oxidation of sulfur in the sintering mix when the temperature was between 800 and 1000ºC; the other behavior was the decomposition of sulfite/sulfate when the temperature was over 1000ºC. However, the SO2 adsorption in the sintering bed mainly occurred in the drying-preheating zone, adsorbed by CaCO3, Ca(OH)2, and CaO. When the SO2 adsorption reaction in the drying-preheating zone reached equilibrium, the excess SO2 gas continued to migrate to the over-wet zone and was then absorbed by Ca(OH)2 and H2O. The emission rising point of SO2 moved forward in combustion zone, and the concentration of SO2 emissions significantly increased in the case of flue gas recirculation (FGR) technique. IMPLICATIONS: Aiming for the reuse of the sensible heat and a reduction in exhaust gas emission, the FGR technique is proposed in the iron ore sintering process. When using the FGR technique, SO2 emission in exhaust gas gets changed. In practice, the application of the FGR technique in a sinter plant should be cooperative with the flue gas desulfurization (FGD) technique. Thus, it is necessary to study the influence of the FGR technique on SO2 emissions because it will directly influence the demand and design of the FGD system.