Preparation and Characterization of Sodium Sulfate/Silica Composite as a Shape-stabilized Phase Change Material by Sol-gel Method

A sodium sulfate （NaeSO4）/silica （SiO2） composite was prepared as a shape-stabilized solid-liquid phase change material by a sol-gel procedure using Na2SiO3 as the silica source. Na2SO4 in the composite acts as a latent heat storage substance for solid-liquid phase change, while SiO2 acts as a support material to provide structural strength and prevent leakage of melted NazSO4. The microstructure and composition of the prepared composite were characterized by the N2 adsorption, transmission electron microscope （TEM）, scanning electron microscope （SEM）, Fourier transform infrared spectroscopy （FTIR） and X-ray diffraction. The results show that the prepared Na2SOJSiO2 composite is a nanostructured hybrid of NazSO4 and SiO2 without new substances produced during the phase change. The macroscopic shape of the NazSO4/SiO2 composite after the melting and freezing cycles does not change and there is no leakage of Na2SO4. Determined by differential scanning calorimeter （DSC） analysis, the values of phase change latent heat of melting and freezing of the prepared NazSO4/SiO2 （50%, by mass） composite are 82.3 kJ.kg i and 83.7 kJ.kg-1, and temperatures of melting and freezing are 886.0 ℃ and 880.6 ℃, respectively. Furthermore, the Na2SOJSiO2 composite maintains good thermal energy storage and release ability even after 100 cycles of melting and freezing. The satisfactory thermal storage performance renders this composite a versatile tool for high-temperature thermal energy storage.

Desiliconization kinetics of nickeliferous laterite ores in molten sodium hydroxide system

A novel process was proposed for treating nickeliferous laterite ores with molten sodium hydroxide.The effect on silicon extraction caused by the factors,such as stirring speed,reaction temperature,particle size and NaOH-to-ore mass ratio,was investigated.The results show that increasing stirring speed,reaction temperature and NaOH-to-ore mass ratio while decreasing particle size increases silicon extraction rate.The desiliconization kinetics of nickeliferous laterite ores in molten sodium hydroxide system was described successfully by chemical reaction control model.The activation energy of the desiliconization process was found to be 44.01 kJ/mol,and the reaction rate based on a chemical reaction-controlled process can be expressed as:1-(1-α) 1/3 = 27.67exp[-44 010/(RT)]t.

RAMAN SPECTRA OF SODIUM ALUMINATE SOLUTIONS WITH HIGH-CAUSTIC RATIO AND HIGH CONCENTRATION

The constitution of high-caustic ratio and highly concentrated sodium aluminate solutions has been investigated by Raman spectra method.By comparison with the Raman spectra of crystalline solids of Ca_3[Al(OH)_6]_2 and Ba_2[Al_2(OH)_(10)],it can be concluded that AI(OH)_6^(3-)ion and perhaps its polymers may be formed in these solutions.

Direct Determination of Potassium-Sodium Activity Ratio in Soil Suspension with Two Ion-Selective Electrodes

A K+-selective electrode and a Na+-selective electrode were used to construct a measuring cell without liquid-junction for the determination of the ion activity ratio of K+ to Na+ in soil suspensions. The measured cell potential was not affected by the total electrolyte concentration when the total cation concentration was 10-1-10-3 mol L-1 and the concentration ratio CK+ / CNa+. was 10:1 to 1:50. When the concentration ratios were equal to 1and the total electrolyte concentrations were 10-2 and 10-3 mol L-1, the ion activity ratio measurement would not be affected by pH in the pH range of 3.5 to 11.5 and 4.4 to 11 respectively. Ions other than H+ have no remarkable influence on the measurement. The ion activity ratio of K+ to Na+ measured directly in soil suspension agree well with those in centrifuged supernant solution. The relative deviation was within 4%. From the measured ion activity ratio, the difference of the bonding energies of K+ and Na+ ions was calculated.

Leaching of vanadium,sodium,and silicon from molten V?Ti-bearing slag obtained from low-grade vanadium-bearing titanomagnetite

The water leaching process of vanadium, sodium, and silicon from molten vanadium-titanium-bearing（V-Ti-bearing） slag obtained from low-grade vanadium-bearing titanomagnetite was investigated systematically. The results show that calcium titanate, sodium aluminosilicate, sodium oxide, silicon dioxide and sodium vanadate are the major components of the molten V-Ti-bearing slag. The experimental results indicate that the liquid-solid（L/S） mass ratio significantly affects the leaching process because of the respective solubilities and diffusion rates of the components. A total of 83.8% of vanadium, 72.8% of sodium, and 16.1% of silicon can be leached out via a triple counter-current leaching process under the optimal conditions of a particle size below 0.074 mm, a temperature of 90°C, a leaching time of 20 min, an L/S mass ratio of 4：1, and a stirring speed of 300 r/min. The kinetics of vanadium leaching is well described by an internal diffusion-controlled model and the apparent activation energy is 11.1 kJ/mol. The leaching mechanism of vanadium was also analyzed.

Electrodeposition of Gold to Conformally Fill High-Aspect-Ratio Nanometric Silicon Grating Trenches: A Comparison of Pulsed and Direct Current Protocols

Filling high-aspect-ratio trenches with gold is a frequent requirement in the fabrication of X-ray optics as well as micro-electronic components and other fabrication processes. Conformal electrodeposition of gold in sub-micron-width silicon trenches with an aspect ratio greater than 35 over a grating area of several square centimeters is challenging and has not been described in the literature previously. A comparison of pulsed plating and constant current plating led to a gold electroplating protocol that reliably filled trenches for such structures.

Corrosion Resistance ofAA6063-Type AI-Mg-Si Alloy by Silicon Carbide in Sodium Chloride Solution for Marine Application

The present work focused on corrosion inhibition of AA6063 type Al-Mg-Si alloy in sodium chloride （NaCI） solution with a silicon carbide inhibitor, using the potentiodynamic electrochemical method. The aluminium alloy surface morphology was examined, in the as-received and as-corroded in the un-inhibited state, with scanning electron microscopy equipped with energy dispersive spectroscopy （SEM-EDS）. The results obtained via linear polarization indicated a high corrosion potential for the unprotected as-received alloy. Equally, inhibition efficiency as high as 98.82% at 10.0 g/v silicon carbide addition was obtained with increased polarization resistance fRy）, while the current density reduced significantly for inhibited samples compared to the un-inhibited aluminium alloy. The adsorption mechanism of the inhibitor aluminium alloy follows the Langmuir adsorption isotherm. This shows that the corrosion rate of aluminium alloy with silicon carbide in NaCI environment decreased significantly with addition of the inhibitor.

Preparation of Al(OH)_3 by ion membrane electrolysis and precipitation of sodium aluminate solution with seeds

The preparation of Al(OH)3 by the ion exchange membrane electrolysis followed by the precipitation of sodium aluminate solution with seeds was made. During the process of ion membrane electrolysis, the sodium aluminate solution is rapidly acidified and the caustic ratio (aK) is decreased due to oxygen evolution in the anodic region. And the causticity of solution is increased due to hydrogen evolution in the cathode region, producing the high concentration of caustic soda solution. Regulating the acidity of the anodic solution by controlling the electric quantity in the electrolysis and subsequent decomposing the solution, Al(OH)3 could yield with very large rate and high efficiency. The experiments also indicate that the quality of aluminum hydroxide product is greatly affected by the impurity silicon.

Effects of ratio of hydrogen flow on microstructure of hydrogenated microcrystalline silicon films deposited by magnetron sputtering at 100 ℃

Hydrogenated microcrystalline silicon(μc-Si:H)films were prepared on glass and silicon substrates by radio frequency magnetron sputtering at 100°C using a mixture of argon(Ar)and hydrogen(H2)gasses as precursor gas.The effects of the ratio of hydrogen flow(H2/(Ar+H2)%)on the microstructure were evaluated.Results show that the microstructure,bonding structure,and surface morphology of theμc-Si:H films can be tailored based on the ratio of hydrogen flow.An amorphous to crystalline phase transition occurred when the ratio of hydrogen flow increased up to 50%.The crystallinity increased and tended to stabilize with the increase in ratio of hydrogen flow from 40%to 70%.The surface roughness of thin films increased,and total hydrogen content decreased as the ratio of hydrogen flow increased.Allμc-Si:H films have a preferred(111)orientation,independent of the ratio of hydrogen flow.And theμc-Si:H films had a dense structure,which shows their excellent resistance to post-oxidation.

Comparative efficacy of sodium glucose cotransporter-2 inhibitors in the management of type 2 diabetes mellitus:A real-world experience

BACKGROUND Sodium glucose cotransporter-2 inhibitors(SGLT-2i)are a class of drugs with modest antidiabetic efficacy,weight loss effect,and cardiovascular benefits as proven by multiple randomised controlled trials(RCTs).However,real-world data on the comparative efficacy and safety of individual SGLT-2i medications is sparse.AIM To study the comparative efficacy and safety of SGLT-2i using real-world clinical data.METHODS We evaluated the comparative efficacy data of 3 SGLT-2i drugs(dapagliflozin,canagliflozin,and empagliflozin)used for treating patients with type 2 diabetes mellitus.Data on the reduction of glycated hemoglobin(HbA1c),body weight,blood pressure(BP),urine albumin creatinine ratio(ACR),and adverse effects were recorded retrospectively.RESULTS Data from 467 patients with a median age of 64(14.8)years,294(62.96%)males and 375(80.5%)Caucasians were analysed.Median diabetes duration was 16.0(9.0)years,and the duration of SGLT-2i use was 3.6(2.1)years.SGLT-2i molecules used were dapagliflozin 10 mg(n=227;48.6%),canagliflozin 300 mg(n=160;34.3%),and empagliflozin 25 mg(n=80;17.1).Baseline median(interquartile range)HbA1c in mmol/mol were:dapagliflozin-78.0(25.3),canagliflozin-80.0(25.5),and empagliflozin-75.0(23.5)respectively.The respective median HbA1c reduction at 12 months and the latest review(just prior to the study)were:66.5(22.8)&69.0(24.0),67.0(16.3)&66.0(28.0),and 67.0(22.5)&66.5(25.8)respectively(P<0.001 for all comparisons from baseline).Significant improvements in body weight(in kilograms)from baseline to study end were noticed with dapagliflozin-101(29.5)to 92.2(25.6),and canagliflozin 100(28.3)to 95.3(27.5)only.Significant reductions in median systolic and diastolic BP,from 144(21)mmHg to 139(23)mmHg;(P=0.015),and from 82(16)mmHg to 78(19)mmHg;(P<0.001)respectively were also observed.A significant reduction of microalbuminuria was observed with canagliflozin only[ACR 14.6(42.6)at baseline to 8.9(23.7)at the study end;P=0.043].Adverse effects of SGLT-2i were as follows:genital thrush and urinary infection-20(8.8%)&17(7.5%)with dapagliflozin;9(5.6%)&5(3.13%)with canagliflozin;and 4(5%)&4(5%)with empagliflozin.Diabetic ketoacidosis was observed in 4(1.8%)with dapagliflozin and 1(0.63%)with canagliflozin.CONCLUSION Treatment of patients with SGLT-2i is associated with statistically significant reductions in HbA1c,body weight,and better than those reported in RCTs,with low side effect profiles.A review of large-scale real-world data is needed to inform better clinical practice decision making.

Removal of boron from metallurgical grade silicon by electromagnetic induction slag melting

A new purification process was developed to remove impurities in metallurgical grade silicon （MG-Si） by electromagnetic induction slag melting （EISM）. Vacuum melting furnace was used to purify boron in different slag systems. The results show that the removal effect in SiO2-CaO-Al2O3 systems is better than that in other slag systems by EISM. The boron content in MG-Si is successfully reduced from 1.5× 10^-5 to 0.2× 10^-5 during EISM at 1 823 K for 2 h. Meanwhile, Al, Ca and Mg elements in MG-Si are also well removed and their removal efficiencies reach 85.0%, 50.2% and 66.7%, respectively, which indicates that EISM is very effective to remove boron and metal impurities in silicon.

增施铵态氮肥诱导滨海盐渍土作物根际降碱抑钠可实现以种适地增产增效

通过改变栽培种植模式激发作物自身抗盐碱的潜力,实现作物以种适地增产增效的目标,对盐碱地绿色产能提升具有重要意义。本试验以滨海盐渍土冬小麦-夏玉米轮作体系为研究对象,采用田间定位试验,设置AS0(100%尿素,磷肥减量)、AS50(50%尿素+50%硫酸铵,磷肥减量)、AS75(25%尿素+75%硫酸铵,磷肥减量)、AS100(100%硫酸铵,磷肥减量)和FP(农民过量施氮磷肥,100%尿素,对照1)、P0(不施磷肥,100%尿素,对照2)6个处理,分析了不同硫酸铵替代尿素比例处理下冬小麦和夏玉米的产量、养分吸收量、氮磷肥利用效率、根际土壤pH、根际土壤盐度和钠吸附比(sodiumadsorptionratio,SAR)的变化。2年田间试验结果表明:P0处理下盐碱地小麦、玉米产量最低,作物生长受到土壤缺磷限制;与FP处理相比,所有减磷处理的作物产量无显著差异。等氮等磷条件下,与全部施用尿素(AS0)处理相比,AS50处理冬小麦平均增产5.4%,夏玉米平均增产1.5%。增施硫酸铵(AS50、AS75、AS100)处理与AS0处理相比小麦根际土壤pH降低0.08~0.24个单位,玉米根际pH降低0.06~0.35个单位。随硫酸铵比例增加,根际土壤速效磷含量呈先增后减的趋势,其中AS50处理速效磷含量最高;根际土壤Ca^(2+)、Na^(+)含量和SAR降低。与FP处理相比,AS50和AS75处理的根际pH、SAR和Na^(+)含量均显著降低,氮磷肥利用效率显著提高;并且玉米季的处理效应比小麦季更显著。在滨海盐渍土区,与FP处理相比,硫酸铵替代50%的尿素能够在磷肥减施的情况下通过诱导根际pH的下降促进SAR和Na^(+)含量降低、提高有效磷和Ca^(2+)含量,营造更适宜作物生长的根际低盐低碱高营养环境,从而提高产量和肥料利用效率。基于以上结果提出了增铵降碱解磷增钙的措施,诱导根土界面肥盐分布区隔化、实现以种适地的轻-中度盐碱地作物增产增效。

Effect of SiO_2/Na_2O mole ratio on the properties of foam geopolymers fabricated from circulating fluidized bed fly ash

Geopolymers are three-dimensional aluminosilicates formed in a short time at low temperature by geopolymerization. In this pa-per, alkali-activated foam geopolymers were fabricated from circulating fluidized bed fly ash （CFA）, and the effect of SiO2/Na2O mole ratio （0.91-1.68） on their properties was studied. Geopolymerization products were characterized by mechanical testing, scanning electron mi-croscopy （SEM）, energy-dispersive X-ray spectroscopy （EDX）, and X-ray diffraction （XRD）. The results show that SiO2/Na2O mole ratio plays an important role in the mechanical and morphological characteristics of geopolymers. Foam samples prepared in 28 d with a SiO2/Na2O mole ratio of 1.42 exhibit the greatest compressive strength of 2.52 MPa. Morphological analysis reveals that these foam geo-polymers appear the relatively optimized pore structure and distribution, which are beneficial to the structure stability. Moreover, a combina-tion of the Si/Al atomic ratio ranging between 1.47 and 1.94 with the Na/Al atomic ratio of about 1 produces the samples with high strength.

Effect of sodium sulfate on strength and microstructure of alkali-activated fly ash based geopolymer

The main objective of this paper focuses on the changes that occur in the strength and microstructural properties of sodium silicate activated fly ash based geopolymer due to varying the sulfate salt and water content.A series of tests including X-ray diffraction,Fourier transform infrared spectroscopy,scanning electron microscopy,physical adsorption and unconfined compressive strength were used to investigate this effect.The results indicate that the higher water content has an adverse effect on the alkali activation and microstructural properties of geopolymer,so the optimum mass ratio of sodium sulfate in alkali-activated geopolymer under different water-to-binder ratios shows a“peak shifting”phenomenon,i.e.,the higher the water-to-binder ratio,the higher the optimum mass ratio.Lower presence of sodium sulfate has no significant effect on the alkali-activated geopolymer systems;higher addition of sodium sulfate,however,could cause the symmetrical stretching vibration of Si—O and the symmetrical stretching vibration of Si—O—Si and Al—O—Si,and promote the formation of N-A-S-H gels.Furthermore,the cement effect of the gel and sodium sulfate aggregate could improve the integrity of pore structure obviously.The maximum strength of geopolymer curing at ambient temperature was 52 MPa.This study obtains the rule that the strength properties of alkali-activated geopolymers vary with the water-to-binder ratio and sodium sulfate content.The feasibility of geopolymer co-activated by sodium sulfate and sodium silicate was investigated,and reference for engineering application of alkali-activated geopolymer in salt-bearing areas was provided.

Desilication kinetics of calcined boron mud in molten sodium hydroxide media

Desilication kinetics of calcined boron mud(CBM) occurring in molten sodium hydroxide media was investigated. The effects of factors such as reaction temperature and Na OH-to-CBM mass ratio on silicon extraction efficiency were studied. The results show that silicon extraction efficiency increases with increasing the reaction time and Na OH-to-CBM mass ratio. There are two stages for the desilication process of the calcined boron mud. The overall desilication process follows the shrinking-core model, and the first and second stages of the process were determined to obey the shrinking-core model for surface chemical reaction and the diffusion through the product layer, respectively. The activation energies of the first and second stages were calculated to be 44.78 k J/mol and 15.94 k J/mol, respectively.

Available Silicon Contents of Paddy Soils and the Effect of Silicon Fertilization on Rice in Sichuan Province

Based on the results of field trials and soil and plant measurements, the available silicon contents ofpaddy soils, their relations with the SiO_2 content of rice plant, the relationships between rice yield on theone hand and the SiO_2 content and SiO_2/N ratio of rice plant on the other, the effects of silicon on riceyield and resistance to diseases and pests and the effective conditions and causes for increasing rice yield inSichuan Basin are expounded in the present paper. The study results show that about one half of the paddysoils developed from yellow soil, purple soil, alluvial soil, etc. in Sichuan Province were insufficient in siliconsupply. Critical values for silicon fertilization were 98 mg kg￣(-1) available Si in the paddy soils and < 112.8gkg￣(-1) SiO_2 in the rice plants. A SiO_2 content of rice plant over 121.6g kg￣(-1) and a SiO_2/N ratio maintainedat about 12 were required for gaining a rice yield of 7500 kg ha￣(-1). The yield increase by silicon fertilizationwas due to the improvement of silicon nutrition in rice plants and the balance of SiO_2/N ratio, and the reasonfor enhanced resistance to diseases and pests was concerned with the inhibition of luxury N absorption andthe raising of plant SiO_2/N ratio. Silicon fertilization tended to balance the uptake of N, P and K by riceplant .

Flotation Separating Rutile from Calcium and Silicon Gangue Minerals

Rutile separation from calcite, apatite and quartz by flotation was investigated. The results show that the rutile separation from calcium and silicon gangue minerals can be realized with alkyl-imino-bismethylene phosphoric acid (TF112) as a collector and sodium hexametaphosphate (SH) as a regulator.

Separation of aluminosilicates and diaspore from diasporic-bauxite by selective flocculation

The flocculation tests of four pure minerals(diaspore,kaolinite,illite,pyrophyllite)and bauxite ore were investigated by the sedimentation.The dispersion behavior of the four pure minerals shows a very good consistency with the variation of zeta potential.The concentrate with the mass ratio of Al2O3 to SiO2(m(Al2O3)/m(SiO2))8.90 and the recovery of Al2O3 86.98%is obtained from bauxite ore(m(Al2O3)/m(SiO2)=5.68)in pH range of 9.5-10.0 by using sodium carbonate(5 kg/t)and sodium polyacrylate(7 g/t)as dispersant and flocculant respectively.Sodium carbonate acts as both pH modifier and favorable dispersant for aluminosilicates.The high performance of sodium polyacrylate on flocculation for diaspore is contributed to the carboxyl of sodium polyacrylate that interacts with active Al sites on diaspore by chemical absorption,and the hydrogen bond effects between hydroxyl group of macromolecule and surface Al—OH on diaspore to accelerate the sedimentation of diaspore.

Effects of temperature and initial molar ratio of Na_2O to Al_2O_3 on agglomeration of fine Al(OH)_3 seed in synthetic Bayer solution

Fine Al（OH）3 crystals were aggregated from supersaturated aluminate solution in the batch reaction tanks. By means of laser particle size analyzer and scanning electron microscopy, the influences of temperature and initial molar ratio of Na2O to Al2O3 （aK） on agglomeration of fine seed in Bayer process were investigated. The results show that agglomeration is almost finished in 8 h, and seeds with size less than 2 μm are easily aggregated together, and almost disappear in 8 h under the optimal process conditions. In the aluminate solution with the same moderate initial aK, when the reaction temperature reaches 75 ℃, the secondary nucleation does not occur, and the effect of agglomeration is better. And at the same reaction temperature, when the initial aK is 1.62, the initial supersaturation of aluminate solution is moderate, the binders on the surfaces of the seed are enough to maintain the agglomeration process, and the agglomeration degree is better. From SEM images, agglomeration mainly occurs in the fine particles, the combinations among the fine particles are loose and the new formed coarse crystal shapes are irregular.

Effect of Binder on the Structure and Properties of Silicon Powder-supported TiO_2 Photocatalysis Material

Recoverable TiO2 photocatalysis material supported by silicon powder was prepared with sol-gel method, afterwards the silica gol and sodium silicate were used as molding binder respectively to investigate their effects （including binder type and binder addition quantity） on the crystal structure and catalysis properties of photocatalyst. In this work, the catalysis activity was defined as the degradation rate of methyl orange solution upon ultraviolet lamp irradiation, and the specific areas were determined with nitrogen desorption method. TiO2 crystal form was measured with X-ray powder diffraction and their micro-morphology was observed with SEM. Experimental results indicate that these two binders do not affect the crystal form transformation of TiO2, but silica gol can increase the specific surface area of TiO2 photocatalyst obviously and the addition of sodium silicate can decrease it. In all, silica gol is a better candidate than sodium silicate for higher catalysis property. In conclusion, 6% silica gol is the optimal addition concentration. Under this condition, the ratio of anatase to rutile TiO2 is 64：36, the specific area is 29.67 m^2/g, and as expected, the degradation rate of methyl orange could be as high as 90% after irradiation for 5 days.