The Kv channel blocker 4-aminopyridine enhances Ag+ uptake: a scanning electrochemical microscopy study of single living cells

We report that silver ion (Ag⁺) uptake is enhanced by 4-aminopyridine (4-AP), a well known voltage-sensitive potassium ion channel (K_v) blocker. Both bacterial (Escherichia coli) and mammalian (3T3 fibroblast) cells were used as model systems. Ag⁺ uptake was monitored with a scanning electrochemical microscope with an amperometric Ag⁺ ion-selective electrode (Ag⁺-ISE) and the respiration rates of E. coli cells were measured by oxygen reduction at an ultramicroelectrode. The results showed that not only the amount but also the rate of silver uptake by the cells increased significantly when 4-AP was added to the solution. For fibroblasts, the Ag⁺ uptake rate was 4.8 × 10⁷ ions per cell per sec without 4-AP compared with 1.0 × 10⁸ ions per cell per sec with 0.2 mM 4-AP. For E. coli cells, the uptake rate was 1.5 × 10⁴ ions per cell per sec without 4-AP vs. 3.5 × 10⁴ ions per cell per sec with 0.5 mM 4-AP and 5.9 × 10⁴ ions per cell per sec with 1 mM 4-AP. Thus, 4-AP might be useful where silver is used as antimicrobial agent to speed its uptake.     

热牙胶温度对AH-Plus根管糊剂所产生根尖微渗漏的影响研究

目的：分析温度对AH-Plus糊剂临床疗效的影响,为一次性根管治疗术中对温度的控制提供临床依据。方法：将48颗牙编号,按随机数字表法分为3组,采用AH-Plus糊剂在不同温度下对离体牙根管进行填充,使用染料渗入法检测微渗漏发生情况,用扫描电镜观察根管壁与封闭剂之间的结合情况。结果：1)在冠方微渗漏方面,不同温度下冠方微渗漏值均没有显著差异(P>0.05);2)在根尖微渗漏方面,C组(230℃)的根尖微渗漏显著小于A(150℃)、B组(180℃)(P<0.05),A、B两组的根尖微渗漏比较没有显著差异(P>0.05);3)扫描电镜对根尖区观察结果显示A组(150℃)的根管壁与牙胶之间缝隙明显大于B、C组。结论：在采用AH-PLUS热牙胶垂直加压技术充填根管时,设定热牙胶温度可能对根尖微渗漏产生影响,较高温度组(230℃)产生的根尖微渗漏小于较低温度组,冠方微渗漏无显著差异。     

A silver enhanced and sensitive strip sensor for Cadmium detection

In this study, an enhanced test strip, based on a monoclonal antibody for the cadmium-ethylenediaminetetraacetic acid (EDTA) complex, but not metal-free EDTA, has been developed. This colorimetric sensor was sensitive and specific for the detection of cadmium in aqueous samples containing excess EDTA. Through a process of silver enhancement, the visual detection limit for Cd(II) was 5 µg/L under optimised conditions and the limit of detection for semi-quantitative detection could be as low as 0.35 µg/L by using a scanning reader. The calibration curve showed that the colour intensity decreased as the Cd(II) concentration increased in the range of 0.5–5 µg/L. The other metal ions did not interfere with the determination of Cd(II). The recoveries of drinking water samples were from 98 to 108%. Consequently, the assay could be employed as a potential on-site screening tool for the detection of Cd(II) in water samples.     

Fabrication of a Low Density Carbon Fiber Foam and Its Characterization as a Strain Gauge

Samples of carbon nano-fiber foam (CFF), essentially a 3D solid mat of intertwined nanofibers of pure carbon, were grown using the Constrained Formation of Fibrous Nanostructures (CoFFiN) process in a steel mold at 550 °C from a palladium particle catalysts exposed to fuel rich mixtures of ethylene and oxygen. The resulting material was studied using Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDX), Surface area analysis (BET), and Thermogravimetric Analysis (TGA). Transient and dynamic mechanical tests clearly demonstrated that the material is viscoelastic. Concomitant mechanical and electrical testing of samples revealed the material to have electrical properties appropriate for application as the sensing element of a strain gauge. The sample resistance versus strain values stabilize after a few compression cycles to show a perfectly linear relationship. Study of microstructure, mechanical and electrical properties of the low density samples confirm the uniqueness of the material: It is formed entirely of independent fibers of diverse diameters that interlock forming a tridimensional body that can be grown into different shapes and sizes at moderate temperatures. It regains its shape after loads are removed, is light weight, presents viscoelastic behavior, thermal stability up to 550 °C, hydrophobicity, and is electrically conductive.     

氢氧化钙糊剂在年轻恒牙牙髓切断术中的应用

目的探讨氢氧化钙糊剂用于年轻恒牙牙髓切断术的临床效果。方法对2016年1月～2017年11月来我科就诊的46例患儿的外伤冠折露髓后行牙髓切断术的51颗年轻恒前牙的治疗效果进行比较分析及随访观察。结果经过1～2年的随访观察,51颗年轻外伤恒牙行牙髓切断术后,成功45颗,失败6颗,成功率为88.2%。不同治疗时间段患者治疗效果对比显示,外伤后就诊越早,露髓孔感染的机率越小,牙髓切断术的成功率就越高,其差异有统计学意义(P0.05)。伤后1～24 h治疗的43颗牙(40例)总有效率为93.0%。结论氢氧化钙糊剂具有很好的杀菌消毒作用,对组织无刺激,可诱导牙本质桥的形成,能有效地保护年轻恒牙的根髓活力,使年轻恒牙的牙根继续发育,并形成良好的根尖形态,建立正常的根尖周组织结构,是年轻恒牙牙髓切断术的首选盖髓剂。     

Silver carbene complexes: An emerging class of anticancer agents

Cancer is a major global health problem with large therapeutic challenges. Although substantial progress has been made in cancer therapy, there still remains a need to develop novel and effective treatment strategies to treat several relapsed and refractory cancers. Recently, there has been growing demand for considering organometallics as antineoplastic agents. This review is focused on a group of organometallics, silver N-heterocyclic carbene complexes (SCCs) and their anticancer efficacy in targeting multiple pathways in various in vitro cancer model systems. However, the precise molecular mechanism of SCCs anticancer properties remains unclear. Here, we discuss the SCCs chemistry, potential molecular targets, possible molecular mechanism of action, and their application in cancer therapies.     

Hierarchical nanostructured conducting polymer hydrogel with high electrochemical activity

Conducting polymer hydrogels represent a unique class of materials that synergizes the advantageous features of hydrogels and organic conductors and have been used in many applications such as bioelectronics and energy storage devices. They are often synthesized by polymerizing conductive polymer monomer within a nonconducting hydrogel matrix, resulting in deterioration of their electrical properties. Here, we report a scalable and versatile synthesis of multifunctional polyaniline (PAni) hydrogel with excellent electronic conductivity and electrochemical properties. With high surface area and three-dimensional porous nanostructures, the PAni hydrogels demonstrated potential as high-performance supercapacitor electrodes with high specific capacitance (~480 F·g(-1)), unprecedented rate capability, and cycling stability (~83% capacitance retention after 10,000 cycles). The PAni hydrogels can also function as the active component of glucose oxidase sensors with fast response time (~0.3 s) and superior sensitivity (~16.7 μA · mM(-1)). The scalable synthesis and excellent electrode performance of the PAni hydrogel make it an attractive candidate for bioelectronics and future-generation energy storage electrodes.     

上颌快速扩弓对颌面组织结构和功能的影响

上颌缩窄是颅面部最常见的骨发育问题之一,可导致严重的错验畸形,并常伴有鼻通气不足、口呼吸和听力下降等功能问题。上颌快速扩弓（RME）作为临床正畸医生常用的上颌扩弓的一种方法,能有效打开处于生长发育期患者的腭中缝,使上颌骨板侧向移动,解除上颌缩窄。研究发现：随着腭中缝的打开,RME使患者颌面部软、硬组织结构发生重塑,进而可以改善鼻通气不足、口呼吸和听力下降等问题,对颌面部组织的功能产生积极影响。本文就RME对颌面组织结构和功能的影响作一综述。