Cordierite Ceramics Prepared from Poor Quality Kaolin for Electric Heater Supports: Sintering Process, Phase Transformation, Microstructure Evolution and Properties

To efficiently utilize the kaolin, an economical way of preparing cordierite ceramic with high performance for electric heater supports was put forward. In this study, sintering process, phase transformation, microstructure evolutions were systematically studied by heating microscope, X-ray diffraction, scanning electronic microscope and thermal analysis. Properties（physical properties, electrical properties and coefficient of thermal expansion（CTE）） were tested for comprehensive performance evaluation. The results showed that the utilization of poor quality kaolin broadened the firing range of cordierite ceramic which was from 1 200 to 1 380 ℃. Microstructure becomes loose with increasing of the pore size, which had significant influence on bending strength and electrical properties. High content of K2 O in poor quality kaolin was the reason for liquid phase generation in sintering process, which further leads to microstructural changes. The cordierite ceramic sintered at 1 320 ℃ had the properties as follows： CTE of 1.98×10^（-6） ℃^（-1）（500 ℃）, bending strength of 90 MPa, apparent porosity of 15.1%, dielectric constant of 7.5（100 Hz）, and volume resistivity of 1.05×109 Ω·cm（100 Hz）. The comprehensive properties are very suitable for use as electric heater supports.

ON THE UTILIZATION OF BAUXITE OF POOR QUALITY

One kind of energy saving and high early strength cement can be produced by using bauxite of poor quality which is refuse before. Through a series of experiments proper chemical compositions of the cement are obtained, and the cement clinker is sintered at a low temperature (1250℃) by the use of the bauxite to the utmost limit. The results show, the cement not only has high early strengths but also has a good characteristic of resisting corrosion by sulphate. So it will be of great practical use. The hydraulic properties of C_4 AF are always problematical, it is studied again in this paper, showing that C_kAF has good hydraulic properties exactly; Cr^(3+), Ni^(3+) and Ti^(4+) can promote the formation of C_4AF and increase its early strengths; CaSO_4·2H_20 can also improve its 3 days' strength but retard its hydration rate espe- cially in early ages.

Derivation and characterization of human embryonic stem cell lines from poor quality embryos

Poor quality embryos discarded from in vitro fertilization （IVF） laboratories are good sources for deriving human embryonic stem cell （hESC） lines. In this study, 166 poor quality embryos donated from IVF centers on day 3 were cultured in a blastocyst medium for 2 days, and 32 early blastocysts were further cultured in a blastocyst optimum culture medium for additional 2 days so that the inner cell masses （ICMs） could be identified and isolated easily. The ICMs of 17 blastocysts were isolated by a mechanical method, while those of the other 15 blastocysts were isolated by immunosurgery. All isolated ICMs were inoculated onto a feeder layer for subcultivation. The rates of ICM attachment, primary ICM colony formation and the efficiency of hESC derivation were similar between the ICMs isolated by the two methods （P〉0.05）. As a result, four new hESC lines were established. Three cell lines had normal karyotypes and one had an unbalanced Robertsonian translocation. All cell lines showed normal hESC characteristics and had the differentiation ability. In conclusion, we established a stable and effective method for hESC isolation and culture, and it was confirmed that the mechanical isolation was an effective method to isolate ICMs from poor embryos. These results further indicate that hESC lines can be derived from poor quality embryos discarded by IVF laboratories.

Effect of vitrification on clinical outcomes of cleavage-stage embryos with poor quality in human embryo cryopreservation

Objective: To evaluate the effect of morphologic factors on survival rate (SR), pregnancy rate (PR), and implantation rate (IR) of human embryo vitrification following frozen embryo transfer (FET) on day 3 post-ovulation.Methods: Women undergoing FET (n = 921) with embryos cryopreserved by vitrification between 2012 and 2013 were enrolled in this retrospective cohort study.Results: Embryos with >9 blastomeres yielded the highest SR of 100%. Lower SR was observed in embryos with 5 to 6 (57.5%) and 4 blastomeres (41.4%). In terms of blastomere symmetry, the SR of embryos with equally sized blastomeres was significantly higher than that of embryos with unequally sized cells (82.5%vs. 64.6%,P < 0.05). As fragmentation increased, SR decreased from 92.1% to 20.6% (P < 0.05). Significant differences were observed among groups when analyzing PR and IR according to the 3 embryonic parameters before vitrification. Embryos with 13 to 16 blastomeres yielded the highest PR (39.5%) and IR (24.1 %). The PR and IR of embryos with blastomeres of equal size were significantly higher than those with unequally sized blastomeres (36.5%vs. 21.7%, 23.7%vs. 12.4%,P < 0.05). After warming, embryos with 13 to 16 blastomeres yielded the highest PR and IR (40.9% and 24.2%, respectively). The PR and IR were observed to grow with an increase in the percentage of intact blastomeres (23.2%-38.2%, 14.2%-23.2%).Conclusions: These results show that vitrification methods do not effectively improve survival outcomes for embryos of poor quality and it is needed to develop a comprehensive vitrification protocol that considers all the practical aspects, including the current limitation regarding cleavage-stage embryos of poor quality.

Recent advances in quality deterioration and improvement of starch in frozen dough

Starch with different particle sizes has different compositions and different physical and chemical properties.The amylopectin content and protein content and lipid content of small granule B starch are higher than that of A-type starch,which can form spiral complex to limit the expansion of starch.Under the same treatment conditions,B-type starch is more vulnerable to damage,sensitive to freezing storage,even breaks in freezing storage,and has higher gelatinization temperature than other starch during freezing.Amylose contained in A-type has high content,high crystallinity,high degree of ordering after frozen storage and insensitivity to frozen storage,which is beneficial to improve the stability of pores and texture of frozen dough.With the extension of freezing time,the content of amylose decreased,while the content of various amylopectin increased and the conformation of polysaccharide changed.Starch deterioration is different under different frozen storage conditions.The deterioration mechanism of frozen dough can be evaluated by variety of starch characteristics during freezing process,which is of great guiding significance to the improvement of frozen dough technology.