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This paper presents a detailed analysis of the effect of slag refining and vacuum treatment on P removal from metallurgical-grade silicon using CaO-SiO2-CaCl2 slag. It demonstrates that both of CaO: SiO2 ratio and CaCl2 content have significant effects on the P removal. Increasing CaO: SiO2 ratio was found to decrease the P removal efficiency after slag refining and vacuum treatment, and the distribution of P shows a tendency to concentrate in the precipitated phase after slag refining. It is also determined that the highest removal efficiency of P was attained when CaCl2 content was 5wt%( CaO:SiO2=1:1), but no obvious change was observed on P distribution after slag refining of varying CaCl2 content.

An innovating slag system, Fe (OH)3-SiO2-CaF2 system, was introduced in the metallurgical methods to purify silicon for photovoltaic application. The partition ratio of boron (LB) between slag and silicon was studied under different mass ratio of slag to silicon and varying mass ratio of Fe (OH)3 to SiO2 under argon condition at 1873K. The distribution of impurity elements in silicon after slag refining was detected by scanning electron scope and electron probe micro analysis. Experimental results illustrated that the Fe-Si binary system could promote the LB. Silicon was surrounded by amorphous slag. Impurity elements are concentrated in slag.

The microstructure and impurities distribution in metallurgical grade silicon with treated by CaO-SiO2 and Na2O-SiO2 slags were investigated. An exhaustive analysis of the transformation of precipitated phase at grain boundaries has been carried out. Prior to slag treatment, Si-Fe system intermetallic was the primary precipitated phase in metalllurgical grade silicon. After treated by CaO-SiO2 slag, Si-Ca system intermetallic became the main precipitated phase, such as Si-Ca, Si-Ca-Ti, Si-Ca-Al and Si-Fe-Ca. But Na2O-SiO2 slag had another result on refining metallurgical grade silicon; only Si-Fe-Ti phase was generated in precipitated phase and the low level of sodium in treated silicon was obtained.

This paper presents a detailed analysis of impurities distribution in metallurgical-grade silicon after CaO-SiO2-CaF2 and CaO-SiO2-CaCl2 slags refining. It demonstrates that the impurities removal efficiency generally increase in metallurgical-grade silicon after CaO-SiO2-CaCl2 slag refining compared to that after CaO-SiO2-CaF2 slag refining. It is also determined that metallic impurities like Fe, Al and Ca tend to co-deposit with Si to form Si-Ca based intermetallic compounds in the precipitate phase after slag refining.

To investigate the effects of the metallurgical route on the defects in mc-Si, various metallurgical routes were conducted. Dislocation formation and the resistivity of the mc-Si were also studied. The results showed that high inhomogeneity in dislocation distribution within individual grains and paralleled tacking faults could be observed when the ingot was grown by using the feedstock prepared by adopting the sequence of slag treatment, acid leaching and vacuum refining. Different grains have various dislocation density, which was showed in ingot grown by utilizing the feedstock prepared by adopting the sequence of vacuum refining, slag treatment and acid leaching, tacking faults could also be seen, as well as some dislocation clusters. The resistivity of this two ingots was detected at various height by using the a 4-point probe silicon tester, it was expected that the resistivity of these two ingots has the same tendency of the change, and the value of the resistivity of the ingot obtained using the previous technology was relatively higher than that of the ingot obtained using the latter technology.

The effects of Na2O-SiO2slag treatment on purification of metallurgical grade silicon by leaching with hydrogen fluoride have been investigated. A comparative analysis of microstructure evolution was carried out to examine the leaching behavior of impurities from metallurgical grade silicon. It was found that the distribution of metal impurities Al, Ca, Ti and Na, which co-deposited with Si and formed different intermetallic phases at grain boundaries, had manifest distinction between precipitated phase and silicon. Moreover, acid corrosion experiment results revealed that slag treatment improved the dissolution rate of metal impurities from metallurgical grade silicon as contrasted to that without slag treatment.

Precipitation phase and impurities distribution of MG-silicon were investigated by vacuum refining followed by slag treatment, and the CaO-SiO2-CaF2 system was adopted for slag treatment. Contrasting the microstructure of precipitated phase in slag treatment with and without vacuum refining pretreated, it could be concluded that the composition of precipitated phases, obtained in MG-Si after vacuum refining followed slag treatment, only consisted of Ca-rich intermetallic silicide phases such as Si-Ca-Ni, Si-Ca-Fe and main impurity phase Si-Ca. And the vacuum refining could make an increase in concentration of the impurity Ti due to its low saturated vapor pressure and silicon loss, which was in favor of the interaction with the impurity B, resulting in the formation of TiB2 that could stay at the slag. Consequently, the vacuum refining could be regarded as an effective method for facilitating the removal of B from MG-Si with slag treatment.

Silicon was purified by solvent refining with Si-Sn binary alloy system. Two descend mold velocities, 10mm/h and 100mm/h were tested in directional solidification of the alloy melt. The morphology, structure and the ingredient of the ingots have been investigated by SEM, XRD, EPMA, GDMS and ICP-MS. The contents of Fe, N, C , Ca, Mn, Cu, P and B are significantly lower than that in raw silicon. Furthermore, the acid leaching experiments were introduced to remove tin from silicon. The temperature of acid leaching and the type of acids were the predominant conditions in tin separation from silicon by acid leaching.

The distribution of impurities in metallurgical grade silicon before and after slag treatment was investigated for the purpose of upgrading metallurgical grade to solar grade silicon. It was found that metal impurities co-deposited with silicon and formed different intermetallics in the precipitated phase, and these intermetallics such as Si-Fe, Si-Ni, Si-Ti-V and Si-Ca-Al-Fe were substituted by Si-Fe-Ti-V after treatment of Na2CO3-SiO2 slag. Non-metallic impurities B and P were nearly homogeneous distribution in metallurgical grade silicon before and after slag treatment. Moreover, a particular analysis of the microstructure of slag has been carried out, it was determined that metal impurities Al and Ca could easily migrate from silicon to slag phase in the refining process.

Objective To explore the clinical features of benign paroxysmal positional vertigo (BPPV) in patients of 40 years old or younger. Methods The clinical features of 40 patients (age ≤40 years) with BPPV admitted from August 2009 to July 2011 were retrospectively analyzed, and compared with that of 286 middle and old-aged patients (age >40 years) with BPPV admitted in the same period. Results The incidence of BPPV in young patients showed a relatively higher incidence (12.3%), with the sex ratio of male to female 1:3 and a mean age of 32.1±6.2 years. The mean latent period of vertigo attack was 1.2±1.3 seconds, and 10 patients (25%) showed no obvious latent period. The median duration of vertigo was 10s. The posterior semicircular canal was involved in 27 patients (67.5%). Cupulolithiasis was found in 6 patients, and all the otolithiasis was found to involve the posterior semicircular canal. The proportion of BPPV with no obvious latency was higher in the young patients than in the middle and old-aged patients (25.0% vs 11.5%, χ2=5.554, P=0.018), but no significant difference in sex ratio, the course of disease, the ratio of involved semicircular canal, the latency and the duration of vertigo attack was found between two groups (P>0.05). Conclusions The incidence of BPPV is relatively higher in youth, more common in females, and the posterior semicircular canal is commonly involved. Compared with the middle and old-aged patients with BPPV, the proportion patients with no obvious latency of vertigo attack in young patients is higher, and the incidence of cupulolithiasis involving posterior semicircular canal is higher in the youth.

Objective To assess the clinical application of Loewenstein Occupational Therapy Cognitive Assessment(LOTCA) in evaluating the impairment of cognition in elderly patients with type 2 diabetes(DM2).Methods Community based 58 elderly patients with DM2 in a community in Shanghai(60 years and older,having received education for 9 years or longer) were enrolled and screened by Mini-Mental State Examination(MMSE).According to the MMSE scores,21 subjects were assigned to case group(MMSE score < 24,implying cognition impairment),and 37 to control group(MMSE score ≥ 24,implying normal cognition).Meanwhile,a group of community-based 40 elderly subjects without DM2(60 years or older,having received education for 9 years or longer,and MMSE score ≥ 24) were enrolled as the blank control.Difference among the baseline data(age,sex ratio and incidence of hypertension) among the 3 groups mentioned above was negligible.The cognition function was assessed with the LOTCA,and the scores acquired were then compared among the 3 groups.Results The total LOTCA scores showed significant difference among the 3 groups.Each LOTCA score,except the score of perception subtest(object identification),was lower in case group than in control and blank group.In control group,the scores were lower than in blank group of the subtest of perception(object constancy),visual-motor organization test and the subtests thereof(reproduction of two-dimensional models,colored and plain block design construction,and reproduction of a puzzle),thinking operation test and the subtests thereof(ROC unstructured,pictorial sequence B,and geometrical sequence),and of concentration test.Conclusions Cognitive impairment may occur in the early stage of elderly patients with DM2.In comparison with MMSE scale,LOTCA is superior in measuring the cognitive impairment during the early stage of elderly DM2 patients and stratifying the severity of the impairment.

To analyze the DNA molecular characters of Centella asiatica with RAPD technology.With the genomic DNA as templates extracted from various source of Centella asiatica samples, optimized RAPD PCR reaction systems had been used. The random promers had been screened to amplify the specific molecular fragments of Centella asiatica.The specific genetic bands of Centella asiatica species from various habitats were established which were highly stable and repeatable and obviously different from those of other families, genuses of plants such as Gynostemma pentaphylum, Tobacco, Cayratia japonica.The developed method of RAPD analysis for the genetic character bands of Centella asiatica could be applied to identify real Centella asiatica from its spurious breed plants. The genetic character bands of Centella asiatica amplified with the RAPD method show high homogeneous in several samples from different habitats.