Impedance analysis on electric double layer capacitor with transmission line model

A new electrode model involving the fractal structure of activated carbon used as electrode material was proposed for an electric double layer capacitor (EDLC). The fractal structure of activate carbon was simulated by branch pore structure of three sizes of cylindrical pores. Three sizes of cylindrical pores were related to macro, meso, and micro pore, since the pore size of activated carbon has wide distribution with a few modes of nm order. The impedance spectrum of EDLC describes the locus of blocking electrode in low frequency range, and the curve at an angle of almost 45° to real axis in high frequency range on the Nyquist plane. The low and high frequency ranges of the impedance spectrum were defined as a lumped constant-type and a distributed constant-type, respectively. Computer simulation of electrochemical impedance with the present electrode model was carried out to understand the relation between the impedance and the electrode structure. The contributions of five parameters to impedance spectrum were discussed, i.e., depth of pore, diameter of pore, specific resistance, the interfacial impedance at electrode/solution, and branch number. The specific resistance p influenced on the shape of impedance spectrum in distributed constant-type range significantly. On other hand, the interfacial impedance at electrode/solution interface controlled the shape of the impedance spectrum in lumped constant-type range. In the course of the curve-fitting to impedance spectrum of EDLC, the separated impedance spectra related to macro, meso, and micro pores were obtained, and the roles of these pores on electric capacity were discussed.     

Fatigue behaviour of dissimilar friction stir welds between wrought and cast aluminium alloys

Wrought aluminium alloy, A6016-T4, was welded to cast one ADC12 by a friction stir welding technique. A6016 was set on the advancing side, while ADC12 was on the retreating side based on the pre-tensile test results. The dissimilar welds exhibited lower fatigue strengths than A6016 but higher than that of ADC12. Fatigue strengths increased when the tool was offset into ADC12, which could be explained based on the risk volume concept. When ADC12 was set on the advancing side, the fatigue strengths decreased. Microstructural observation revealed that the macroscopic structure in the stir zone drastically changed by putting ADC12 on the advancing side, and insufficient mixing of dissimilar alloys resulted in the lower fatigue strengths.     

A new control scheme of a cascaded transformer type multilevel PWM inverter for a residential photovoltaic power conditioning system

From the viewpoint of high quality output voltage generation in a residential photovoltaic system, a multilevel inverter employing cascaded transformers can become a good substitute for the conventional pulse width modulated inverters and other multilevel counterparts. However, to obtain more sinusoidal output voltage waves, it should increase the number of switching devices and transformers resulting in a cost increase. To alleviate this problem, an efficient switching pattern is proposed and applied to a multilevel inverter equipped with two cascaded transformers, which have a series-connected secondary. Operational principle and analysis are illustrated focusing on a change of the switching pattern. High-performance of the proposed multilevel scheme embedded in a photovoltaic power conditioning system is verified by computer-aided simulations and experimental results.     

Indoor sorption of surrogates for sarin and related nerve agents

Sorption rate parameters were determined for three organophosphorus (OP) compounds [dimethyl methylphosphonate (DMMP), diethyl ethylphosphonate (DEEP), and triethyl phosphate (TEP)] as surrogates for the G-type nerve agents sarin (GB), soman (GD), and tabun (GA). OP surrogates were injected and vaporized with additional volatile organic compounds into a 50 m3 chamber finished with painted wallboard. Experiments were conducted at two furnishing levels: (i) chamber containing only hard surfaces including a desk, a bookcase, tables, and chairs and (ii) with the addition of plush materials including carpet with cushion, draperies, and upholstered furniture. Each furnishing level was studied with aged and new painted wallboard. Gas-phase concentrations were measured during sealed chamber adsorb and desorb phases and then fit to three mathematical variations of a previously proposed sorption model having a surface sink and allowing for an embedded sink. A four-parameter model allowing unequal transport rates between surface and embedded sinks provided excellent fits for all conditions. To evaluate the potential effect of sorption, this model was incorporated into an indoor air quality simulation model to predict indoor concentrations of a G-type agent and a nonsorbing agent for hypothetical outdoor releases with shelter-in-place (SIP) response. Sorption was simulated using a range of parameters obtained experimentally. Simulations considered outdoor Gaussian plumes of 1- and 5-h duration and infiltration rates of 0.1, 0.3, and 0.9 h(-1). Indoor toxic loads (TL) for a 10-h SIP were calculated as integral C2 dt for a G-type agent. For the 5-h plume, sheltering reduced TLs for the nonsorbing agent to approximately 10-65% of outdoor levels. Analogous TLs for a G-type agent were 2-31% or 0.3-12% of outdoor levels assuming slow or moderate sorption. The relative effect of sorption was more pronounced for the longer plume and higher infiltration rates.     

Two-Dimensional Numerical Model of Spillway Flow

A numerical model using the finite-element and finite-volume methods is developed for the resolution of two-dimensional free-surface flow equations including air entrainment and applied to calculation of the flow in a spillway. The model is implemented on an unstructured triangular mesh where the standard Galerkin scheme and an upwind finite-volume scheme are developed to solve the continuity and the conservative momentum equations, respectively. The time integration is performed using the fourth-order-accurate Runge-Kutta method with time steps that satisfy the Courant-Friedrichs-Lewy condition. An artificial dispersion term is introduced to eliminate spurious oscillations. A test problem in a spillway is solved to verify the applicability of the model to practical design. A physically realistic solution is obtained that represents a series of flow state alternations from supercritical to subcritical and vice versa, as well as the surface level increase due to the entrained air. The temporal mean of the calculated solution is compared with experimental temporal mean data and examined by posteriorly evaluating the residual term due to vertical nonhomogeneity of velocity. The investigations prove that the model is valid as a primary analysis tool for hydraulic design of spillways.     

A Dystrophin Exon-52 Deleted Miniature Pig Model of Duchenne Muscular Dystrophy and Evaluation of Exon Skipping

Duchenne muscular dystrophy (DMD) is a lethal X-linked recessive disorder caused by mutations in the DMD gene and the subsequent lack of dystrophin protein. Recently, phosphorodiamidate morpholino oligomer (PMO)-antisense oligonucleotides (ASOs) targeting exon 51 or 53 to reestablish the DMD reading frame have received regulatory approval as commercially available drugs. However, their applicability and efficacy remain limited to particular patients. Large animal models and exon skipping evaluation are essential to facilitate ASO development together with a deeper understanding of dystrophinopathies. Using recombinant adeno-associated virus-mediated gene targeting and somatic cell nuclear transfer, we generated a Yucatan miniature pig model of DMD with an exon 52 deletion mutation equivalent to one of the most common mutations seen in patients. Exon 52-deleted mRNA expression and dystrophin deficiency were confirmed in the skeletal and cardiac muscles of DMD pigs. Accordingly, dystrophin-associated proteins failed to be recruited to the sarcolemma. The DMD pigs manifested early disease onset with severe bodywide skeletal muscle degeneration and with poor growth accompanied by a physical abnormality, but with no obvious cardiac phenotype. We also demonstrated that in primary DMD pig skeletal muscle cells, the genetically engineered exon-52 deleted pig DMD gene enables the evaluation of exon 51 or 53 skipping with PMO and its advanced technology, peptide-conjugated PMO. The results show that the DMD pigs developed here can be an appropriate large animal model for evaluating in vivo exon skipping efficacy.     

Harnessing Topology and Stereochemistry of Glycidylamine-Derived Lipid Nanoparticles for in Vivo mRNA Delivery to Immune Cells in Spleen and Their Application for Cancer Vaccination

mRNA lipid nanoparticles (LNPs) have reached an inflection point and are now paving the way for a new wave of precision therapies. The design of nonhepatocyte RNA delivery systems without targeting ligands, however, remains a challenge. It is reported that the development of ligand-free glycidylamine (GA) derivatives containing LNPs (GA-LNPs) that preferentially deliver mRNA to immune cells in the spleen. Notably, it is demonstrated that the stereochemistry of GA-lipids has a significant impact on their self-assembly and in vitro and in vivo RNA delivery efficiency and tropism. This impact is dependent on the monomeric structure of GA and number of stereogenic centers. Furthermore, the nonlinear topology of GA lipid derivatives induced a sevenfold improvement in mRNA delivery efficiency. The top-performing estriol-GA05-30 LNPs elicited strong antitumor activity in a therapeutic and prophylactic cancer model and are well tolerated in mice. These results highlight the significance of the chemistry of ionizable lipids for extrahepatic RNA delivery and indicated a promising direction for the development of next-generation mRNA immunotherapies.     

Varying the Directionality of Protein Catalysts for Aldol and Retro-Aldol Reactions

Natural aldolase enzymes and created retro-aldolase protein catalysts often catalyze both aldol and retro-aldol reactions depending on the concentrations of the reactants and the products. Here, we report that the directionality of protein catalysts can be altered by replacing one amino acid. The protein catalyst derived from a scaffold of a previously reported retro-aldolase catalyst, catalyzed aldol reactions more efficiently than the previously reported retro-aldolase catalyst. The retro-aldolase catalyst efficiently catalyzed the retro-aldol reaction but was less efficient in catalyzing the aldol reaction. The results indicate that protein catalysts with varying levels of directionality in usually reversibly catalyzed aldol and retro-aldol reactions can be generated from the same protein scaffold.