Layer-by-layer self-assembly of single-walled carbon nanotubes with amine-functionalized weak polyelectrolytes for electrochemically tunable pH sensitivity

The layer-by-layer (LbL) assembly of carboxylated single-walled carbon nanotubes (SWCNT) is demonstrated to tune the electrochemical pH sensitivity of thin-film devices. The positively charged amine containing weak polyelectrolyte (wPE) is used as a counter species to control the proximal ions. The LbL assembly process is monitored by the quartz crystal microbalance, which results in the linear growth of a multilayer. The amount adsorbed is strongly dependent on the surface charge of previously deposited species. However, the thickness of the multilayer is determined by both the amount adsorbed and the coiling of polyelectrolyte chains. Indeed, electrical and structural characteristics of the (wPE/SWCNT) multilayer thin film are obtained according to the acid dissociation constants of amino groups in wPE. The electrochemical pH sensitivity in the physiological range demonstrates the effects of both charge carrier doping/trapping and proximal ions on the conductance of the SWCNT multilayer. Although doping/trapping shows the decreasing conductance, the proximal ion effect reveals the increasing conductance with pH in the basic region as a result of the p-type semiconducting nature of SWCNTs and the ability of wPE to capture hydrogen ions. This work sheds light on the applicability of nanostructured and/or engineered functional thin films of SWCNTs as chemical and biological sensors.     

Discovery of the serum biomarker proteins in severe preeclampsia by proteomic analysis

Preeclapsia (PE) is a severe disorder that occurs during pregnancy, leading to maternal and fetal morbidity and mortality. PE affects about 3-8% of all pregnancies. In this study, we conducted liquid chromatography- mass spectrometry/mass spectrometry (LC-MS/MS) to analyze serum samples depleted of the six most abundant proteins from normal and PE-affected pregnancies to profile serum proteins. A total of 237 proteins were confidently identified with <1% false discovery rate from the two groups of duplicate analysis. The expression levels of those identified proteins were compared semiquantitatively by spectral counting. To further validate the candidate proteins with a quantitative mass spectrometric method, selective reaction monitoring (SRM) and enzyme linked immune assay (ELISA) of serum samples collected from pregnant women with severe PE (n = 8) or normal pregnant women (n = 5) was conducted. α2- HS-glycoprotein (AHSG), retinol binding protein 4 (RBP4) and α-1-microglobulin/bikunin (AMBP) and Insulin like growth factor binding protein, acid labile subunit (IGFBP-ALS) were confirmed to be differentially expressed in PE using SRM (P<0.05). Among these proteins, AHSG was verified by ELISA and showed a statistically significant increase in PE samples when compared to controls.     

Synthesis of Substituted Coumarins via Brønsted Acid Mediated Condensation of Allenes with Substituted Phenols or Anisoles

Coumarins were obtained from the condensation of electron-rich arenes with allenes in the presence of TfOH in good yield. Depending on the substituent pattern of allenes employed, the general synthetic method of 4-substituted and 3,4-disubstituted 3-arylcoumarins has been developed. Readily available allenes were employed as the three-carbon atom sources constituting the coumarin skeleton.     

负相关样本平滑移动过程的矩完全收敛性(英文)

本文研究了负相关样本平滑移动过程Xk=∑∞i=-∞ai+kYi的矩完全收敛性,这里{Yi,-∞相似文献