Effects of MgO/Al2O3 ratio on viscous behaviors and structures of MgO-Al2O3-TiO2-CaO-SiO2 slag systems with high TiO2 content and low CaO/SiO2 ratio

The effects of MgO/Al2 O3 ratio on the viscous behaviors of MgO-Al2 O3-TiO2-CaO-SiO2 systems were investigated by the rotating cylinder method.Raman spectroscopy was used to analyze the structural characteristics of slag and Factsage 7.0 was adopted to demonstrate the liquidus temperature of slag.The results show that the viscosity and activation energy for viscous flow decrease when the MgO/Al2O3 ratio increases from 0.82 to 1.36.The break point temperature and liquidus temperature of slag initially decrease and subsequently increase.The complex viscous structures are gradually depolymerized to simple structural units.In conclusion,with the increase of MgO/Al2O3 ratio,the degree of polymerization of slag decreases,which improves the fluidity of slag.The variations of liquidus temperature of slag lead to the same changes of break point temperature.

Detection of STAT2 in early stage of cervical premalignancy and in cervical cancer

Objective:To measure the expression pattern of STAT2 in cenical cancer initiation and progression in tissue sections from patients with cervicitis,dysplasia,and cenical cancer. Methods:Antibody against human STAT2 was confirmed by plasmids transient transfection and Western blot Immunohistochemistry was used to delect STAT2 expression in the cervical biopsies by using the confirmed antibody against STAT2 as the primary antibody.Results:It was found that the overall rate of positive STAT2 expression in the cervicitis,dysplasia and cenical cancer groups were 38.5%,69.49%and 76.991,respectively.The STAT2 levels are significantly increased in premalignant dysplasia and cervical cancer,as compared lo cervicitis(P【 0.05). Noticeably,STAT2 signals were mainly found in the cytoplasm,implying that STAT2 was not biologically active.Conclusions:These findings reveal an association between cenical cancer progression and augmented STAT2 expression.In conclusion.STAT2 increase appears to be an early detectable cellular event in cenical cancer development.

Seroprevalence of Toxoplasma gondii infection in dogs and cats in Zhenjiang City,Eastern China

Objective:To determine the seroprevalence of Toxoplasma gondii(T.gondii) infection in dogs and cats in Zhenjiang City,Jiangsu Province.Eastern China,and to evaluate the main associated risk factors relating to exposure to 71 gondii in this region.Methods:Sera from 160 clogs and 116 cats from Zhenjiang City were tested for anti-T.gondii antibodies using EUSA.The seropositivity by area of activity,sex and age was analyzed.Results:Overall.21 dogs(13.l%) and 24 cats(20.7%) had antibodies to T.gondii.The infection rate in stray dogs(38.7%) and cats(28.6%! was significantly higher(P<0.05) than in household dogs(6.9%) and cats(18.2%).The seroprevalence in male clogs(14.8%) and cats(21.05%) were slighlly higher than their female counterparts(11.4%in dogs and 20.0%in cats),but were not significantly differenent(P>0.05).A high proportion of dogs at 3 to 6 years of age were positive to T.gondii(20.0%)while cats with relatively high seropositivity rates were at 0 to 1 year of age(33.3%).Conclusions:The prevalence of T.gondii infection in dogs and cats in Zhenjiang City was high,which is probably the main source of T.gondii infection in this area.

Stepwise recovery of magnesium from low-grade ludwigite ore based on innovative and clean technological route

A novel and clean technological route for the comprehensive utilization of low-grade ludwigite ore was proposed, inwhich magnesium was extracted by metallizing reduction？magnetic separation, sulfuric acid leaching and ethanol precipitationoperation. Meanwhile, iron-rich product, silicon-rich product and boron-rich product were obtained, respectively. In the process ofmetallizing reduction-magnetic separation, 94.6% of magnesium was enriched in the non-magnetic substance from the ore reducedat 1250 ℃ for 60 min with the ore size of 0.50-2.00 mm and coal size of 0.50-1.50 mm. When the non-magnetic substance wasleached at 90 ℃ for 15 min with the liquid-to-solid ratio of 7：1, 87.4% of magnesium was leached into the liquor separated fromsilicon gathering in leaching residue. The ethanol precipitation was conducted for 30 min with the ethanol-to-original liquid volumeratio of 1.5：1 at room temperature. 97.2% of magnesium was precipitated out with the initial concentration of 0.8 mol/L in the formof MgSO4·7H2O.

Broadband diffusion of terahertz waves by multi-bit coding metasurfaces

The terahertz region is a special region of the electromagnetic spectrum that incorporates the advantages of both microwaves and infrared light waves.In the past decade,metamaterials with effective medium parameters or gradient phases have been studied to control terahertz waves and realize functional devices.Here,we present a new approach to manipulate terahertz waves by using coding metasurfaces that are composed of digital coding elements.We propose a general coding unit based on a Minkowski closed-loop particle that is capable of generating 1-bit coding(with two phase states of 0 and 180°),2-bit coding(with four phase states of 0,90°,180°,and 270°),and multi-bit coding elements in the terahertz frequencies by using different geometric scales.We show that multi-bit coding metasurfaces have strong abilities to control terahertz waves by designing-specific coding sequences.As an application,we demonstrate a new scattering strategy of terahertz waves—broadband and wide-angle diffusion—using a 2-bit coding metasurface with a special coding design and verify it by both numerical simulations and experiments.The presented method opens a new route to reducing the scattering of terahertz waves.

Modeling assessment of recovering iron from red mud by direct reduction： magnetic separation based on response surface methodology

Red mud, the waste generated during alumina production, contains iron and other valuable metals. To recover the iron efficiently from red mud, a three-factor five-level central composite design in response surface methodology was used to study the effects of process parameters, such as FC/O （the molar ratio of fixed carbon in coal to reducible oxygen of iron oxide in red mud）, reduction temperature, reduction time, and their interaction on the iron recovery rate and total iron content in magnetic product obtained from the process of direct reduction-magnetic separation. The relevant assessment model was established. The model could predict the changing rules of iron recovery rate and total iron content in the magnetic product affected by the process parameters. The results show that the iron recovery rate is significantly influenced by three factors and reduction temperature plays the most important role. The iron recovery rate and total iron content in magnetic product could be up to 98.37 and 82.52%, respectively, under the numerically optimal process parameters condition of reduction temperature of 1400 ℃, FC/O of 0.80 and reduction time of 100 min obtained by the assessment model. The predicted values are in good agreement with the experimental values.

Oxidation mechanism and non-isothermal kinetic studies on carbonate iron ore by thermogravimetric analysis

Due to the uncertain and heterogeneous compositions of carbonate iron ore after magnetization roasting,an oxidation pretreatment was applied to increase the uniformity of the composition of the ore.The oxidation of carbonate iron ore was characterized using a thermogravimetric method over a temperature range of 723-948 K.It is shown that the oxidation process of carbonate iron ore is complicated and consists of multiple reactions that include the decomposition and oxidation of carbonates such as FeCO3,MnCO3,MgCO3 and CaMg(CO3)2.The main product that results from oxidation is Fe2O3.Because of the low content of other carbonates (MnCO3,MgCO3 and CaMg(CO3)2)in raw carbonate iron ore and the small change in the apparent activation energies during oxidation,the oxidation of carbonate iron ore can be treated as a single-step FeCO3 oxidation reaction.Based on the Ozawa-Flynn-Wall method,which is one of the model-free methods, the apparent activation energy for the oxidation of carbonate iron ore is 284.50 kJ mol^-1.The most probable reaction model for the oxidation of carbonate iron ore is the Sestak-Berggren model as determined by the theoretical and actual master plot and eigenvalues of the Malek method.The reaction orders n and m are 1.317 and 0.0295,respectively.The preexponential factor is 2.628 ×10^17 min^-1.