CDK5-dependent inhibitory phosphorylation of Drp1 during neuronal maturation

Mitochondrial functions are essential for the survival and function of neurons. Recently, it has been demonstrated that mitochondrial functions are highly associated with mitochondrial morphology, which is dynamically changed by the balance between fusion and fission. Mitochondrial morphology is primarily controlled by the activation of dynamin-related proteins including dynamin-related protein 1 (Drp1), which promotes mitochondrial fission. Drp1 activity is regulated by several post-translational modifications, thereby modifying mitochondrial morphology. Here, we found that phosphorylation of Drp1 at serine 616 (S616) is mediated by cyclin-dependent kinase 5 (CDK5) in post-mitotic rat neurons. Perturbation of CDK5 activity modified the level of Drp1^S616 phosphorylation and mitochondrial morphology in neurons. In addition, phosphorylated Drp1^S616 preferentially localized as a cytosolic monomer compared with total Drp1. Furthermore, roscovitine, a chemical inhibitor of CDKs, increased oligomerization and mitochondrial translocation of Drp1, suggesting that CDK5-dependent phosphorylation of Drp1 serves to reduce Drp1''s fission-promoting activity. Taken together, we propose that CDK5 has a significant role in the regulation of mitochondrial morphology via inhibitory phosphorylation of Drp1^S616 in post-mitotic neurons.     

Enhanced interfacial adhesion,mechanical, and thermal properties of natural flour-filled biodegradable polymer bio-composites

This study examined the interfacial adhesion, mechanical, and thermal properties of compatibilizing agent-treated and non-treated biocomposites as a function of the type of compatibilizing agent. The tensile strength, interfacial adhesion, and heat deflection temperature (HDT) of maleic anhydride-grafted poly(butylene succinate) (PBS-MA) and maleic anhydride-grafted poly(lactic acid) (PLA-MA)-treated biocomposites are greater than those of untreated maleic anhydride-grafted poly(styrene-b-ethylene-co-butylene-b-styrene) triblock copolymer (SEBS-MA) and maleic anhydride-grafted polypropylene (MAPP)-treated biocomposites. The storage modulus (E′) values and the tan δ_max temperatures (T _g) of PBS-MA and PLA-MA-treated biocomposites were slightly higher than that of the untreated biocomposites.     

Electrorheological fluid characterization via a vertical oscillation rheometer

A custom designed vertical oscillation rheometer (VOR) is used for the rheological measurements of electrorheological (ER) fluids consisting of 15 and 20 vol.% semiconducting polyaniline particles suspended in silicone oil. The viscoelastic material functions, including complex viscosity and complex shear modulus, are measured via geometric parameters, measured force, and applied strain of the VOR. Viscoelastic properties of the ER fluids are also measured as a function of applied electric field strength and particle concentration. The VOR, equipped with a high voltage generator, can easily be constructed and used to measure ER properties. It is further found that polyaniline suspensions behave as viscoelastic materials in an electric field. In linear viscoelastic conditions, elasticity was promoted with the increment of electric field due to particle chain structure in the presence of the applied electric field. It is also found that the applied electric field rather than particle concentration enhanced the elasticity of ER fluids.     

Quantitative immunoassay for determining polyaromatic hydrocarbons in electrical insulating oils

The development and application of a combined sample extraction and immunoassay protocol for the quantification of polyaromatic hydrocarbons (PAHs) in transformer oils is reported. Tests were performed on 12 different used transformer oils from three major manufacturers. The removal of matrix interferents was achieved by loading oil fractions onto silica solid phase extraction cartridges and eluting with non-polar solvent prior to evaporation and reconstitution in a more polar medium. Extracts were immunoassayed using two commercially available PAH test kits either having broad specificity towards priority PAHs or enhanced binding specificity toward more carcinogenic PAHs. The total and carcinogenic PAH test kits yielded PAH levels in the oil extracts 5.86-fold and 126-fold lower than the industry-standard IP346 method. The latter method, widely used by the industry, since it correlates with biological carcinogenicity tests, grossly over-estimates PAH levels in oils since it is a non-specific gravimetric solvent extraction approach. The assay was found to be unaffected by the extract sample matrix and was capable of determining PAHs at the nanogram per millilitre level. The assay protocol was simple, low-cost and rapid (<2 h) and equally amenable to operation at remote sites or high-throughput sample screening. The binding specificity of the total anti-PAH antibody was examined by preparing and loading an anti-PAH immunosorbent with oil, prior to solvent displacement of antibody-bound compounds and by gas chromatography (GC)–mass spectrometry (MS) analysis.     

A continuous monitor for assessment of 222Rn in the coastal ocean

Radon-222 is a good natural tracer of groundwater flow into the coastalocean. Unfortunately, its usefulness is limited by the time consuming natureof collecting individual samples and traditional analysis schemes. We demonstratehere an automated system which can determine, on a continuousbasis, the radon activity in coastal ocean waters. The system analyses ²²²Rn from a constant stream of water passing through an air-water exchangerthat distributes radon from the running flow of water to a closed air loop.The air stream is feed to a commercial radon-in-air monitor which determinesthe concentration of ²²²Rn by collection and measurement of theemitting daughters, ²¹⁴Po and ²¹⁸Po, via a charged semiconductordetector. Since the distribution of radon at equilibrium between the air andwater phases is governed by a well-known temperature dependence, the radonconcentration in the water is easily calculated.     

Photocatalytic Effects of Rutile Phase TiO2 Ultrafine Powder with High Specific Surface Area Obtained by a Homogeneous Precipitation Process at Low Temperatures

The photocatalytic characteristics of nanostructured TiO₂ ultrafine powder with rutile phase produced using the homogeneous precipitation process at low temperatures (HPPLT) were compared with those of commercial P-25 TiO₂ powder by flame hydrolysis. The TiO₂ powder by the HPPLT showed much higher photoactivity in the removal rate, showing lower pH values in the solution than the P-25 powder when eliminating metal ions such as Pb and Cu from the aqueous metal-EDTA solutions. This can be inferred as the more rapid photo-oxidation or -reduction of metal ions from the aqueous solution, together with relatively higher efficiencies in the use of an electron-hole pair formed on the surface of the TiO₂ particles under UV light irradiation. Also, in the view of the TiO₂ particle morphology, compared to the well-dispersed spherical P-25 particles, the agglomerated TiO₂ secondary particles by the HPPLT consist of acicular typed primary particles with a thickness in the range of 3–7 nm and the primary particles radialize in all directions, which would be more effective to photocatalytic reactions without the large electron-hole recombination on the surface of the TiO₂ particle under UV light irradiation. It can be, therefore, thought that the higher photoactivity of the rutile TiO₂ powder by the HPPLT in the aqueous solutions results mainly from having a larger surface area by the acicular shaped primary particles with very thin thickness and radialization in all directions.     

Characterization of the Converging Jet Region in a Triple Torch Plasma Reactor

Enthalpy probe measurements were taken of the converging plasma plume in a triple torch plasma reactor and related to substrate heat flux measurements. Results show excellent entrainment of process gases injected into the converging plasma plume by way of the central injection probe. At lower pressures (40 kPa), the plasma volume is equivalent to at least a 3 cm diameter, 4 cm long cylinder, with relatively uniform temperature, velocity, and substrate heat flux profiles when compared to a typical dc arc jet. Converging plasma plume size, substrate heat flux, and enthalpy profiles are also shown to be a strong function of applied system power. Substrate heat flux measurements show smaller radial gradients than enthalpy probe measurements, because of the high radial velocity component of gases above the substrate boundary layer. Enthalpy probe measurements were also conducted for diamond deposition conditions and approximate temperature and velocity profiles obtained. Problems with the uniform gas mixture assumption prohibited more accurate measurements. Reproducibility of enthalpy measurement results was shown with an average standard deviation of 11.8% for the velocity and 7.6% for the temperature measurements.