Yb2SiO5稀土硅酸盐环境障涂层研究进展

环境障涂层体系历经三代的发展,稀土硅酸盐因其具有低热膨胀系数、优良的抗水氧腐蚀性能与相稳定性,且与中间层莫来石化学相容性好,已成为研究热点。本文重点论述稀土硅酸盐Yb2SiO5环境障涂层的制备方法、涂层形貌、相结构影响以及裂纹机制、抗高温水蒸气腐蚀及抗CMAS腐蚀性能的研究进展。并指出了以Yb2SiO5为代表的稀土硅酸盐体系值得关注的问题及未来环境障涂层的发展趋势。

纳米YSZ热障涂层高温时效过程中组织演变研究

燃气轮机长期运行过程中,热端部件如燃烧室内壁和前级涡轮叶片长期经受高温火焰冲击,涂层材料会产生时效行为。在时效过程中,热障涂层会发生组织演变,影响涂层性能与寿命。本文对一种高纯纳米YSZ热障涂层进行了不同温度的时效考核,研究材料在高温中组织演变行为,并对涂层孔隙率变化规律进行了热动力学分析。结果表明,在高温过程中,YSZ涂层中残留的纳米界面会进一步融合并逐渐演变为微米晶;受热动力学机制支配,涂层中孔隙闭合消损,造成涂层孔隙率下降。另外,本文还统计分析了涂层的相变行为。

低烧损ZrB2/SiC复合粉末制备及涂层抗烧蚀性能研究

采用喷雾造粒-胶粘包覆的方法制备了一种低烧损核壳结构ZrB2/SiC复合粉末,研究了胶粘包覆过程中不同清漆含量对粉末包覆效果的影响。结果表明清漆含量不足时细粉包覆不完全,细粉出现单独团聚的现象;清漆含量过多时,造成原始球形颗粒的粘连;当清漆含量为4.5%时,获得包覆效果良好的粉末,外层包覆完整均匀。为了研究等离子喷涂过程中核壳结构粉末SiC发生分解烧损程度,对比了分别采用核壳结构和均匀弥散结构ZrB2/SiC复合粉末所制备涂层的微观形貌及涂层中元素分布。结果表明核壳结构粉末喷涂涂层成分均匀性良好,高熔点ZrB2保护内层SiC,可有效减少SiC在等离子焰流中的烧损,实现涂层和粉末成分的一致性。对核壳结构复合粉末制备的涂层进行了20s的氧-乙炔火焰烧蚀试验,涂层质量烧蚀率为1.837×10-3g/s,对涂层抗烧蚀机理进行了初步探讨。

HVOF制备MCrAlY涂层过程中WC杂质颗粒的演变遗传行为研究

在热喷涂工业生产过程中,喷涂制备不同材料体系的涂层之前需要对送粉路径(送粉罐、送粉盘、搅拌器、送粉管路、送粉针)进行清理,但由于送粉路径内部结构复杂且存在静电吸附效应,使得残留于喷涂系统的粉末无法被完全去除,通常以微量杂质颗粒的形式被带入新涂层,进而影响新涂层的性能。为此,本文研究了在单晶基材表面采用高速火焰(HVOF)喷涂制备MCrAlY涂层过程中,送粉路径残留的WC杂质颗粒(WC-10Co4Cr)在涂层及涂层与基材界面处的遗传演变行为,分别采用SEM、EDS分析了WC杂质在喷涂态、热处理态涂层中的微观组织和相组成。研究结果表明,WC杂质颗粒确实存在于MCrAlY涂层中,并在后期热处理及氧化试验中进一步分解而固溶于涂层中,甚至扩散至单晶基材内部引起含W碳化物的生成,影响涂层及单晶基材的显微组织,改变局部的成分均匀性。同时,本文还采用ThermoCalc软件进行了热力学计算模拟,辅助分析了WC分解及W与C元素在显微组织中的遗传特性。对于WC类粉末和MCrAlY粉末共用的HVOF喷涂设备,建议给MCrAlY粉末配备单独的送粉路径,以确保涂层的纯净度与质量。

Corrigendum to “Establishment and functional characterization of the reversibly immortalized mouse glomerular podocytes (imPODs)” [Genes & Diseases 5 (2018) 137–149]

The authors regret having an image assembly error in Figure 3A,in which the image for "imPOD Synaptopodin DAPl stain"groupwas erroneouslyduplicatedwiththe imagefrom the"tsPOD-33C SynaptopodinDAPIstain"group.We confirm the error is restricted to the image assembly,and the underlying data and conclusions are correct and unchanged.The authors would like to apologize for any inconvenience caused.

Corrigendum to “The development of a sensitive fluorescent protein-based transcript reporter for high throughput screening of negative modulators of lncRNAs” [Genes & Diseases 5 (2018) 62–74]

The authors regret having an image assembly error in Figure 5Ca,in which the image for the "Oh dBiFP-AdRFp"group was erroneously duplicated with an overlapping image from the"36h BiFP dBIFP-AdR-simH19"group.We confirm the error is restricted to the image assembly,and the underlying data and conclusions are correct and unchanged.The authors would like to apologize for any inconvenience caused.

Corrigendum to “Characterization of the essential role of bone morphogenetic protein 9 (BMP9) in osteogenic differentiation of mesenchymal stem cells (MSCs) through RNA interference” [Genes & Diseases 5(2018):172–184]

The authors regret having several image assembly errors.Specifically,in Figure 3A panel b,the image for "AdsimB9-4 only"group was erroneously duplicated with an overlapping image from the"AdRFp"group;and the image for"AdsimB9-1+BMP9"groupwas erroneouslyduplicatedwithan overlapping image from"AdsimB9-8+BMP9"group.In Figure 4Apanel a,the images for"BMP9"group and "BMP9+simB9-4"group were erroneously duplicated with an overlapping image from"simB9-4"group.In Figure 5A,the image for"BMP9+simB9-4/Day3"group was erroneously duplicated with an overlapping image from"BMP9+simB9-7/Day3"group;and the image for"BMP9+simB9-4/Day5"group was erroneously duplicated with an overlapping image from an unrelated experiment.In Figure 6B,the image for"BMP9+simB9-7/Day 11"group was erroneously duplicated with an overlapping image from the"BMP9+simB9-4/Day 11"group.

Breast cancer development and progression:Risk factors,cancer stem cells,signaling pathways,genomics,and molecular pathogenesis

As the most commonly occurring cancer in women worldwide,breast cancer poses a formidable public health challenge on a global scale.Breast cancer consists of a group of biologically and molecularly heterogeneous diseases originated from the breast.While the risk factors associated with this cancer varies with respect to other cancers,genetic predisposition,most notably mutations in BRCA1 or BRCA2 gene,is an important causative factor for this malignancy.Breast cancers can begin in different areas of the breast,such as the ducts,the lobules,or the tissue in between.Within the large group of diverse breast carcinomas,there are various denoted types of breast cancer based on their invasiveness relative to the primary tumor sites.It is important to distinguish between the various subtypes because they have different prognoses and treatment implications.As there are remarkable parallels between normal development and breast cancer progression at the molecular level,it has been postulated that breast cancer may be derived from mammary cancer stem cells.Normal breast development and mammary stem cells are regulated by several signaling pathways,such as estrogen receptors(ERs),HER2,and Wnt/b-catenin signaling pathways,which control stem cell proliferation,cell death,cell differentiation,and cell motility.Furthermore,emerging evidence indicates that epigenetic regulations and noncoding RNAs may play important roles in breast cancer development and may contribute to the heterogeneity and metastatic aspects of breast cancer,especially for triple-negative breast cancer.This review provides a comprehensive survey of the molecular,cellular and genetic aspects of breast cancer.

Characterization of the essential role of bone morphogenetic protein 9 (BMP9) in osteogenic differentiation of mesenchymal stem cells (MSCs) through RNA interference

Mesenchymal stem cells(MSCs)are multipotent stem cells and capable of differentiating into multiple cell types including osteoblastic,chondrogenic and adipogenic lineages.We previously identified BMP9 as one of the most potent BMPs that induce osteoblastic differentiation of MSCs although exact molecular mechanism through which BMP9 regulates osteogenic differentiation remains to be fully understood.Here,we seek to develop a recombinant adenovirus system to optimally silence mouse BMP9 and then characterize the important role of BMP9 in osteogenic differentiation of MSCs.Using two different siRNA bioinformatic prediction programs,we design five siRNAs targeting mouse BMP9(or simB9),which are expressed under the control of the converging H1 and U6 promoters in recombinant adenovirus vectors.We demonstrate that two of the five siRNAs,simB9-4 and simB9-7,exhibit the highest efficiency on silencing exogenous mouse BMP9 in MSCs.Furthermore,simB9-4 and simB9-7 act synergistically in inhibiting BMP9-induced expression of osteogenic markers,matrix mineralization and ectopic bone formation from MSCs.Thus,our findings demonstrate the important role of BMP9 in osteogenic differentiation of MSCs.The characterized simB9 siRNAs may be used as an important tool to investigate the molecular mechanism behind BMP9 osteogenic signaling.Our results also indicate that recombinant adenovirus-mediated expression of siRNAs is efficient and sustained,and thus may be used as an effective delivery vehicle of siRNA therapeutics.

Establishment and functional characterization of the reversibly immortalized mouse glomerular podocytes(imPODs)

Glomerular podocytes are highly specialized epithelial cells and play an essential role in establishing the selective permeability of the glomerular filtration barrier of kidney.Maintaining the viability and structural integrity of podocytes is critical to the clinical management of glomerular diseases,which requires a thorough understanding of podocyte cell biology.As mature podocytes lose proliferative capacity,a conditionally SV40 mutant tsA58-immortalized mouse podocyte line(designated as tsPC)was established from the Immortomouse over 20 years ago.However,the utility of the tsPC cells is hampered by the practical inconvenience of culturing these cells.In this study,we establish a user-friendly and reversibly-immortalized mouse podocyte line(designated as imPOD),on the basis of the tsPC cells by stably expressing the wildtype SV40 T-antigen,which is flanked with FRT sites.We show the imPOD cells exhibit long-term high proliferative activity,which can be effectively reversed by FLP recombinase.The imPOD cells express most podocyte-related markers,including WT-1,Nephrin,Tubulin and Vinculin,but not differentiation marker Synaptopodin.The imPOD cells do not form tumor-like masses in vivo.We further demonstrate that TGFb1 induces a podocyte injury-like response in the FLP-reverted imPOD cells by suppressing the expression of slit diaphragm-associated proteins P-Cadherin and ZO-1 and upregulating the expression of mesenchymal markers,a-SMA,Vimentin and Nestin,as well as fibrogenic factors CTGF and Col1a1.Collectively,our results strongly demonstrate that the newly engineered im-POD cells should be a valuable tool to study podocyte biology both under normal and under pathological conditions.

The development of a sensitive fluorescent protein-based transcript reporter for high throughput screening of negative modulators of lncRNAs

While the human genome is pervasively transcribed,<2%of the human genome is transcribed into protein-coding mRNAs,leaving most of the transcripts as noncoding RNAs,such as microRNAs and long-noncoding RNAs(lncRNAs),which are critical components of epigenetic regulation.lncRNAs are emerging as critical regulators of gene expression and genomic stability.However,it remains largely unknown about how lncRNAs are regulated.Here,we develop a highly sensitive and dynamic reporter that allows us to identify and/or monitor negative modulators of lncRNA transcript levels in a high throughput fashion.Specifically,we engineer a fluorescent fusion protein by fusing three copies of the PEST destruction domain of mouse ornithine decarboxylase(MODC)to the C-terminal end of the codon-optimized bilirubin-inducible fluorescent protein,designated as dBiFP,and show that the dBiFP protein is highly destabilized,compared with the commonly-used eGFP protein.We further demonstrate that the dBiFP signal is effectively down-regulated when the dBiFP and mouse lncRNA H19 chimeric transcript is silenced by mouse H19-specific siRNAs.Therefore,our results strongly suggest that the dBiFP fusion protein may serve as a sensitive and dynamic transcript reporter to monitor the inhibition of lncRNAs by microRNAs,synthetic regulatory RNA molecules,RNA binding proteins,and/or small molecule inhibitors so that novel and efficacious inhibitors targeting the epigenetic circuit can be discovered to treat human diseases such as cancer and other chronic disorders.

Breast cancer development and progression: Risk factors, cancer stem cells, signaling pathways, genomics, and molecular pathogenesis

As the most commonly occurring cancer in women worldwide,breast cancer poses a formidable public health challenge on a global scale.Breast cancer consists of a group of biologically and molecularly heterogeneous diseases originated from the breast.While the risk factors associated with this cancer varies with respect to other cancers,genetic predisposition,most notably mutations in BRCA1 or BRCA2 gene,is an important causative factor for this malignancy.Breast cancers can begin in different areas of the breast,such as the ducts,the lobules,or the tissue in between.Within the large group of diverse breast carcinomas,there are various denoted types of breast cancer based on their invasiveness relative to the primary tumor sites.It is important to distinguish between the various subtypes because they have different prognoses and treatment implications.As there are remarkable parallels between normal development and breast cancer progression at the molecular level,it has been postulated that breast cancer may be derived from mammary cancer stem cells.Normal breast development and mammary stem cells are regulated by several signaling pathways,such as estrogen receptors(ERs),HER2,and Wnt/b-catenin signaling pathways,which control stem cell proliferation,cell death,cell differentiation,and cell motility.Furthermore,emerging evidence indicates that epigenetic regulations and noncoding RNAs may play important roles in breast cancer development and may contribute to the heterogeneity and metastatic aspects of breast cancer,especially for triple-negative breast cancer.This review provides a comprehensive survey of the molecular,cellular and genetic aspects of breast cancer.