Microstructure and properties of Si_3N_4 ceramics obtained from addition of β-phase seeds and celsian

The silicon nitride based ceramics obtained by the addition of β-Si3N4 seeds was fabricated using celsian as the additive and by pressureless sintering. The microstructure of the material was observed and analyzed using XRD, SEM, and TEM and the mechanical response of this array microstructure was characterized for flexural strength and fracture behavior. The result shows that the growth of the larger aspect ratio grains initiate mainly from the seeds through the heterogeneous nucleation mechanism during the process of phase transformation, and the intergranular phase BaAl2Si20s services as good refractory materials. In contrast to conventional processing, a stable bimodal microstructure and complicated component with a lower cost can be achieved using the abovementioned process theoretically and practically.

Effects of 1-Naphthol on Physiological Parameters of Chlorella vulgaris

[ Objective] This study aimed to investigate the effects of 1-naphthol on primary productivity in aquatic ecosystems. [ Method] The effects of 1-naphthol on biomass, chlorophyll a content, malondialdehyde （MDA） content and soluble protein content of Chlorella vulgaris were investigated. [ Result] 1-Naphthol could significantly inhibit the growth of Chlorella vulgaris. On the 7^th d, the biomass of Chlorella vulgaris exposed to 1.0, 3.0, 6.0, 12.0 and 18.0 mg/L 1-naphthol was 60.26%, 48.15%, 41.32%, 28.59% and 27.10% of that in control respectively, exhibiting a significant dose-response relationship. Chlorella vulgaris was exposed to different concentrations of 1-naphthol （0, 1,5 and 10 mg/L） for 7 d ; with the increase of 1-naphthol concentration, chlorophyll a content of Ch/orella vulgaris was reduced, MDA content increased gradually, soluble protein content increased first and then declined. [ Conclusion] According to the experimental results, 1-naphthol can significantly inhibit the growth of Chlorella vulgaris, thus reducing primary productivity in aquatic ecosystems.

Nucleophilic amino acids as a renewable alternative to petrochemically-derived amines in glycerol epoxy resins

The standard epoxy resin curing agents revealed are from unsustainable petroleum-based sources,which produce poisonous exhaust when cured.Amino acids,a bio-based epoxy curing agent with amino and carboxyl groups,are another potential curing agent.Water-soluble epoxy resins cured with lysine(Lys),glutamic acid(Glu),leucine(Leu),and serine(Ser)as amino acids were inves-tigated.The results showed that the water-soluble epoxy resin(glycerol epoxy resins,GER)was cured with Lys and Glu after reacting.Fourier transform infrared(FT-IR)spectroscopic analysis of the GER-Lys showed that the amino and carboxyl groups of Lys primarily reacted with the epoxy groups of GER.The elongation at break of Lys-cured GER(GER-Lys)cured at 70℃ with a molar ratio of 1꞉0.75 was 75.32%.The fact that elongations at break of GER-Lys(79.43%)were higher than those of GER-Glu(17.33%),respectively supports the decrease of crosslinking density by the amino acid-cured GER reaction.The potential of Lys and Glu alternatives for petrochemical amines is demonstrated and provides promising opportunities for industrial application.

Biliary spontaneous dislodgement spiral stent for short-term biliary drainage in patients undergoing complete stone removal:A randomized controlled study

To the Editor:Endoscopic retrograde cholangiopancreatography(ERCP)is strongly recommended for stone removal of choledocholithiasis.But there is still risk of complications such as post-ERCP cholangitis(PEC)and post-ERCP pancreatitis(PEP).Biliary drainage including endoscopic nasobiliary drainage(ENBD)and biliary stent is considered to reduce the occurrence of PEC and PEP.However,the ENBD tube will cause patient discomfort,and some patients may extract the tube by themselves.Furthermore,additional endoscopic stent removal is required after insertion of conventional biliary stent for short-term biliary drainage,increasing medical costs.

不同生境内啮齿动物对辽东栎幼苗的频率依赖性捕食及其对幼苗生长与存活的影响

啮齿动物对辽东栎(Quercus wutaishanica)种子的侵袭取决于种子的大小及其捕食频率。然而,啮齿动物对幼苗的捕食是否具有频率依赖性还不清楚。本研究在宁夏六盘山区辽东栎次生林内,选取林窗和林下两种生境,按5个种子大小频率(9:1,7:3,5:5,3:7和1:9)移栽萌发生根的辽东栎幼苗,探究啮齿动物对幼苗子叶的频率依赖性捕食及其对幼苗生长与存活的影响。研究结果表明:(i)幼苗移栽初期(1-7天),啮齿动物更偏好大种子建立幼苗的子叶。然而,移栽后8-60天,啮齿动物更偏好小种子建立幼苗的子叶,即表现为正频率依赖性捕食。(ii)尽管幼苗捕食率在林下高于林窗,但经过一个生长周期后,林窗内幼苗存活率高于林下(分别为5.40%和2.00%)。(iii)捕食子叶对辽东栎幼苗生长无显著影响,但顶芽被咬掉后幼苗各生长参数均显著降低(P<0.05)。这些结果不仅为啮齿动物和不同表型辽东栎幼苗的共存提供了新的见解,还揭示了栎树幼苗的更新策略。