Nanocomposites of iridium oxide and conducting polymers as electroactive phases in biological media

Much effort is currently devoted to implementing new materials in electrodes that will be used in the central nervous system, either for functional electrostimulation or for tests on nerve regeneration. Their main aim is to improve the charge capacity of the electrodes, while preventing damaging secondary reactions, such as peroxide formation, occurring while applying the electric field. Thus, hybrids may represent a new generation of materials. Two novel hybrid materials are synthesized using three known biocompatible materials tested in the neural system: polypyrrole (PPy), poly(3,4-ethylenedioxythiophene) (PEDOT) and iridium oxide (IrO₂). In particular, PPy–IrO₂ and PEDOT–IrO₂ hybrid nanocomposite materials are prepared by chemical polymerization in hydrothermal conditions, using IrO₂ as oxidizing agent. The reaction yields a significant ordered new hybrid where the conducting polymer is formed around the IrO₂ nanoparticles, encapsulating them. Scanning electron microscopy and backscattering techniques show the extent of the encapsulation. Both X-ray photoelectron and Fourier transform infrared spectroscopies identify the components of the phases, as well as the absence of impurities. Electrochemical properties of the final phases in powder and pellet form are evaluated by cyclic voltammetry. Biocompatibility is tested with MTT toxicity tests using primary cultures of cortical neurons grown in vitro for 6 and 9 days.     

Ability of new obturation materials to improve the seal of the root canal system: A review

New obturation biomaterials have been introduced over the past decade to improve the seal of the root canal system. However, it is not clear whether they have really produced a three-dimensional impervious seal that is important for reducing diseases associated with root canal treatment. A review of the literature was performed to identify models that have been employed for evaluating the seal of the root canal system. In vitro and in vivo models are not totally adept at quantifying the seal of root canals obturated with classic materials. Thus, one has to resort to clinical outcomes to examine whether there are real benefits associated with the use of recently introduced materials for obturating root canals. However, there is no simple answer because endodontic treatment outcomes are influenced by a host of other predictors that are more likely to take precedence over the influence of obturation materials. From the perspective of clinical performance, classic root filling materials have stood the test of time. Because many of the recently introduced materials are so new, there is not enough evidence yet to support their ability to improve clinical performance. This emphasizes the need to translate anecdotal information into clinically relevant research data on new biomaterials.     

CLINICAL TRIAL: A RANDOMIZED STUDY COMPARING THE DURABILITY OF SILICONE AND LATEX PERCUTANEOUS ENDOSCOPIC GASTROSTOMY TUBES

Background: The use of percutaneous endoscopic gastrostomy (PEG) for nutrition support is increasing worldwide, but few studies have evaluated the durability of and complications related to the different materials used to manufacture gastrostomy tubes. Latex PEG tubes are widely used in our clinical setting, but no studies have compared their durability with silicone PEG tubes. The aim of the present study was to compare the durability of latex tubes with the durability of silicone tubes. Patients and Methods: A randomized clinical trial was conducted in patients with head and neck cancer with indications for PEG. Sixty patients were randomized to receive either latex or silicone PEG tubes and followed up for 90 days. The analyzed outcomes were duration, peristomal infection, granulated tissue formation, and leakage around the tube. Results: The durability of silicone PEG tubes was significantly greater than the durability of latex PEG tubes. The survival curves showed that silicone PEG tubes lasted twice as long (hazard ratio = 2.0, 95% confidence interval = 1.1–3.7, P = 0.01). No differences were found with regard to rate of peristomal infection, granulated tissue formation, or leakage. Conclusion: Silicone PEG tubes are associated with a reduced need for replacement (attributable to higher durability) compared with latex PEG tubes.     

Micrograin Superplasticity: Characteristics and Utilization

Micrograin Superplasticity refers to the ability of fine-grained materials (1 µm < d < 10 μm, where d is the grain size) to exhibit extensive neck-free elongations during deformation at elevated temperatures. Over the past three decades, good progress has been made in rationalizing this phenomenon. The present paper provides a brief review on this progress in several areas that have been related to: (a) the mechanical characteristics of micrograin superplasticity and their origin; (b) the effect of impurity content and type on deformation behavior, boundary sliding, and cavitation during superplastic deformation; (c) the formation of cavity stringers; (d) dislocation activities and role during superplastic flow; and (e) the utilization of superplasticity.     

Recent advances in the treatment of hilar cholangiocarcinoma: portal vein embolization

The clinical application of portal vein embolization (PVE) has contributed to improving the postoperative outcome of hilar cholangiocarcinoma. The enlarged nonembolized lobe after PVE protects the patient from postoperative hepatic failure, due to the increased functional reserve, and shortens the hospital stay. Although numerous reports have shown beneficial effects of PVE on postoperative outcome after extended hepatectomy, no randomized controlled study has been performed so far. It is urgent to establish a “gold standard” of PVE, because the indications, approach to the portal vein, types of embolic materials, and methods used to evaluate the function of the future liver remnant are variable among institutions. The indications and procedures of PVE for hilar cholangiocarcinoma may be different from those for hepatocellular carcinoma or colorectal metastasis, because, in many patients with hilar cholangiocarcinoma, biliary cancer is associated with biliary obstruction and cholangitis. This review article summarizes the contribution of PVE to the outcome of postoperative management in patients with hilar cholangiocarcinoma needing extended hepatectomy. We also describe our PVE procedure, which has been established from our experience of more than 240 cases of biliary cancer. Furthermore, the drawbacks of PVE, which may reduce the pool of candidates for surgery, are also discussed.     

亲水凝胶骨架材料制备盐酸多奈哌齐缓释片的可行性研究

目的 采用亲水凝胶骨架材料制备盐酸多奈哌齐缓释片,并对其质量进行评价。方法 采用亲水凝胶骨架材料HPMC K100LV和K4M联用通过干法制粒工艺制备盐酸多奈哌齐缓释片,以溶出曲线相似性f2值作为评价指标,通过正交设计进行处方优化,用高效液相色谱法进行含量和杂质检测,通过加速和长期试验考察片剂稳定性。结果 以该方法制备的盐酸多奈哌齐缓释片质量稳定,具有与原研制剂一致的溶出特征。结论 以该方法制备盐酸多奈哌齐缓释片具有可行性。     

Nanocomposite Foams of Polypropylene and Carbon Nanotubes: Preparation,Characterization, and Evaluation of their Performance as EMI Absorbers

Highly expanded nanocomposite foams of polypropylene and carbon nanotubes (PP/CNT) are formed using supercritical carbon dioxide (scCO₂) technology. The foaming parameters (temperature, pressure) are investigated to establish their influence on the morphology of the resulting foams and their impact on the electrical conductivity. As promising electromagnetic‐interference (EMI) absorbers, the EMI shielding performance of the foams is determined, and a preliminary relationship is established between foam morphology and the EMI shielding performance. The best candidates are highly expanded foams with a volume expansion of >25, containing 0.1 vol% CNTs; they are able to absorb more than 90% of the incident radiation between 25 and 40 GHz.