An Electrocorticography Grid with Conductive Nanoparticles in a Polymer Thick Film on an Organic Substrate Improves CT and MR Imaging.

Purpose To develop an electrocorticography (ECoG) grid by using deposition of conductive nanoparticles in a polymer thick film on an organic substrate (PTFOS) that induces minimal, if any, artifacts on computed tomographic (CT) and magnetic resonance (MR) images and is safe in terms of tissue reactivity and MR heating. Materials and Methods All procedures were approved by the Animal Care and Use Committee and complied with the Public Health Services Guide for the Care and Use of Animals. Electrical functioning of PTFOS for cortical recording and stimulation was tested in two mice. PTFOS disks were implanted in two mice; after 30 days, the tissues surrounding the implants were harvested, and tissue injury was studied by using immunostaining. Five neurosurgeons rated mechanical properties of PTFOS compared with conventional grids by using a three-level Likert scale. Temperature increases during 30 minutes of 3-T MR imaging were measured in a head phantom with no grid, a conventional grid, and a PTFOS grid. Two neuroradiologists rated artifacts on CT and MR images of a cadaveric head specimen with no grid, a conventional grid, and a PTFOS grid by using a four-level Likert scale, and the mean ratings were compared between grids. Results Oscillatory local field potentials were captured with cortical recordings. Cortical stimulations in motor cortex elicited muscle contractions. PTFOS implants caused no adverse tissue reaction. Mechanical properties were rated superior to conventional grids (χ(2) test, P < .05). The temperature increase during MR imaging for the three cases of no grid, PTFOS grid, and conventional grid was 3.84°C, 4.05°C, and 10.13°C, respectively. PTFOS induced no appreciable artifacts on CT and MR images, and PTFOS image quality was rated significantly higher than that with conventional grids (two-tailed t test, P < .05). Conclusion PTFOS grids may be an attractive alternative to conventional ECoG grids with regard to mechanical properties, 3-T MR heating profile, and CT and MR imaging artifacts. (©) RSNA, 2016 Online supplemental material is available for this article.

[Determination of free amino acids in Eriocheir sinensis by ultra-high performance liquid chromatography-high resolution mass spectrometry].

Eriocheir sinensis is a unique freshwater crab found in China, which is well known for its rich nutrition and sweet and delicious taste. Free amino acids in Eriocheir sinensis are not only important nutrients but also are closely related to their unique taste and aroma. Therefore, the determination of the free amino acid contents in Eriocheir sinensis is of great significance for product quality evaluation, flavor research, authenticity, and origin identification. Herein we proposed an ultra-high performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS)-based method for the determination of 17 free amino acids in Eriocheir sinensis. First, 5 g of the Eriocheir sinensis sample was weighed into a 50-mL polypropylene centrifuge tube. Then, 10 mL of extraction solvents was added to the centrifuge tube, and the resultant solution was mixed well using a vortex mixer. We compared a variety of solvents and finally selected 5%(v/v) perchloric acid aqueous solution as the optimum extraction solvent. The supernatant was transferred to another polypropylene centrifuge tube after centrifuging at 8000 r/min for 5 min. The extraction procedure was repeated according to the above-mentioned steps, and the extraction solution was combined with the supernatant. The extracts were then adjusted to pH 6.5 with 1 mol/L potassium hydroxide solution, and were diluted to 50 mL with water. After filtering by both qualitative filter paper and a 0.45-µm polyether sulfone syringe filter, the extracts were determined by UHPLC-HRMS. We compared three types of mobile phases and chose 0.1%(v/v) formic acid aqueous solution mixed with acetonitrile as the optimum one. Precise parent ion and ion source parameters were also optimized. The 17 analytes, viz. aspartic acid, threonine, serine, glutamic acid, proline, cystine, valine, methionine, isoleucine, leucine, tyrosine, phenylalanine, lysine, arginine, glycine, alanine, and histidine, were separated on an XDB-C18 column (100 mm×4.6 mm, 1.7 µm) with gradient elution. The amino acids were then detected by HRMS in electrospray ionization and selected ion monitoring modes, and the analytes were quantified using external standards. The instrumental detection limit (IDL) and the instrumental quantification limit (IQL) were 0.3 mg/L and 1.0 mg/L, respectively. The linear correlation coefficients were all above 0.9990 in the concentration range of 10.0-200.0 mg/kg. Three levels of free amino acid standards were spiked into the edible parts of Eriocheir sinensis. The recoveries of the amino acids were between 78.4% and 105.3%. The intra-sample, intra-day, and inter-day repeatabilities were below 4.2%, 5.2%, and 11.4%, respectively, which were within reasonable ranges. Twenty samples of Eriocheir sinensis were tested using the proposed method. Thus, in this study, we developed an alternative method for the determination of free amino acids in Eriocheir sinensis with simple pretreatment, good selectivity, and high accuracy.

Synthesis, characterization and evaluation of dewatering properties of chitosan-grafting DMDAAC flocculants.

Flocculation is one of the most widely applied techniques for water treatment and sludge dewatering. A fresh environmentally friendly and powerful flocculant is highly eager in the sludge dewatering area. In this work, a highly efficient cationic flocculant, chitosan-g-PDMDAAC was synthesized through grafting a monomer, dimethy ldiallyl ammonium chloride(DMDAAC), onto chitosan initiated by ceric sulfate under ultrasonic-assisted and conventional heating condition. The graft copolymer was characterized using FT-IR, XRD and SEM. Further, the dewatering performance of municipal activated sludge was evaluated by the filter cake moisture content and specific resistance in filtration. Its application as a flocculant for wastewater treatment was investigated. The prepared chitosan-g-PDMDAAC showed a highly effective flocculation capability for activated sludge compared with chitosan, polyacrylamide(PAM), cationic polyacrylamide(CPAM).

Effects of a bolaamphiphile on the structure of phosphatidylcholine liposomes.

This paper describes the morphological characterization of aqueous dispersions of PC amphiphiles and bolaamphiphile AEC by microscopy, the liposomal membrane fluidity, and the zeta potential. Results indicate that the bolaamphiphile AEC can be included within conventional egg-PC liposome bilayers. This behavior could be due to their preference for the stretched conformation within the PC membranes.