Discharge behaviors and jet profiles during electrospinning of poly(vinyl alcohol)

Relations between beads formation and jet profiles, and beads formation and electric discharge during electrospinning were investigated by changing sample parameters and spinning conditions. The jet profiles were obtained as a function of the position along the spinning line by using photographs. As the molecular weight or concentration increased, the elongational viscosity of jet at the onset of bending instability was increased, and beads formation was suppressed. In addition, beads formation was enhanced with increasing voltage. The electric discharge spark from the apex of cone was observed by using image intensified high‐speed camera. It was found that the beads were also formed easily when the electric discharge generated. POLYM. ENG. SCI., 50:1788–1796, 2010. © 2010 Society of Plastics Engineers     

Helical Antimicrobial Peptide Foldamers Containing Non-proteinogenic Amino Acids

Antimicrobial peptides (AMPs) are potential novel therapeutic drugs against microbial infections. Most AMPs function by disrupting microbial membranes because of their amphipathic properties and ordered secondary structures. In this minireview, we describe recent efforts to develop helical AMP foldamers containing non-proteinogenic amino acids, such as α,α-disubstituted α-amino acids, β-amino acids, γ-amino acids, side-chain stapling and N-alkyl glycines.     

Controlled synthesis of sulfonated block copolymers having thermoresponsive property by RAFT polymerization of vinyl sulfonate esters

Four vinyl sulfonate ester derivatives, methyl ethenesulfonate (MES), ethyl ethenesulfonate (EES), 2,2,2-trifluoroethyl ethenesulfonate (TFES), and 2,2,2-trichloroethyl ethenesulfonate (TCLES), which are protected forms of vinyl sulfonic acids, were polymerized by reversible addition-fragmentation chain transfer (RAFT) polymerization. Polymers having relatively narrow molecular weight distributions and pre-determined molecular weights were obtained by the polymerization of all monomers using a suitable xanthate-type chain transfer agent (CTA). The RAFT polymerizations of EES and TCLES were found to proceed in controlled fashions under suitable conditions, as confirmed by the formation of narrow polydispersity products, molecular weights controlled by the monomer/chain transfer agent ratio, and linear increases in molecular weight with conversion. Deprotection of the ethyl group of poly(EES) by LiBr in refluxing 2-butanone proceeded smoothly to give water-soluble poly(lithium vinyl sulfonate). Poly(potassium vinyl sulfonate) was also obtained by the deprotection of poly(TCLES) using potassium tert-butoxide. The syntheses of thermoresponsive block copolymers involving poly(lithium vinyl sulfonate) segments were conducted by RAFT polymerization of N-isopropylacrylamide using poly(EES) macro-CTA, followed by deprotection. The thermally-induced phase separation behavior and assembled structures of the block copolymers were also studied in aqueous solution.     

A Helix‐Stabilized Cell‐Penetrating Peptide as an Intracellular Delivery Tool

Two types of cationic cyclic α,α‐disubstituted α‐amino acids: Api (which possesses a lysine mimic side chain) and Api^C2Gu (which possesses an arginine mimic side chain), were developed. These amino acids were incorporated into an arginine‐based peptide sequence [(l ‐Arg‐l ‐Arg‐dAA)₃: dAA=Api or Api^C2Gu], and the relationship between the secondary structures of the resulting peptides and their ability to pass through cell membranes was investigated. The peptide containing Api^C2Gu formed a stable α‐helical structure and was more effective at penetrating cells than the nonhelical Arg nonapeptide (R₉). Furthermore, the peptide was able to deliver plasmid DNA into various types of cells in a highly efficient manner.     

A Generalization of Magic Squares with Applications to Digital Halftoning

A semimagic square of order n is an n×n matrix containing the integers 0,…,n ²−1 arranged in such a way that each row and column add up to the same value. We generalize this notion to that of a zero k×k -discrepancy matrix by replacing the requirement that the sum of each row and each column be the same by that of requiring that the sum of the entries in each k×k square contiguous submatrix be the same. We show that such matrices exist if k and n are both even, and do not if k and n are relatively prime. Further, the existence is also guaranteed whenever n=k ^m , for some integers k,m≥2. We present a space-efficient algorithm for constructing such a matrix. Another class that we call constant-gap matrices arises in this construction. We give a characterization of such matrices. An application to digital halftoning is also mentioned. A preliminary version of this paper appeared in Proceedings of International Symposium on Algorithms and Computation, Hong Kong, December, 2004. Part of the work on the paper has been carried out when B.A. was visiting JAIST. Work of B.A. on this paper was supported in part by NSF ITR Grant CCR-00-81964. Work of T.A. was partially supported by the Ministry of Education, Science, Sports and Culture, Grant-in-Aid for Scientific Research (B).     

A criterion for reverse control action of TCUL controls and their deactivation timings

The dynamic behaviors of the TCUL controls are investigated from the viewpoint of the effect of control actions on voltage stability as well as on voltage regulations, taking into account the interference among the multiple control actions of TCULS. The Liapunov stability theorem is applied to a system having nonlinear voltage-dependent loads to derive conditions for stability. We define the term “reverse control action for multiple TCULS” to indicate undesirable tap operations, where multiple controls as a whole cause the decrease in voltages of specific nodes, leading to voltage collapse, in spite of normal individual operations. A criterion to detect the phenomena is derived and then a new control strategy based on this criterion is demonstrated. In this demonstration, unsuitably acting TCULs are individually deactivated at their most effective timings to improve voltage stability. The effectiveness of the proposed criterion and its application to the deactivation control have successfully been confirmed through numerical simulations in a radial network with three cascaded TCUL transformers, where a specific area of a real system is reduced to form the example system.     

Multiple Pre-Treatment miRNAs Levels in Untreated Major Depressive Disorder Patients Predict Early Response to Antidepressants and Interact with Key Pathways

Major depressive disorder (MDD) is a life-impairing disorder, and early successful treatment is important for a favorable prognosis. However, early response to antidepressants differs widely among individuals, and is difficult to predict pre-treatment. As miRNAs have been reported to play important roles in depression, identification of miRNAs associated with antidepressant treatment responses and their interacting genes and pathways will be beneficial in understanding the predictors and molecular mechanisms of depression treatment. This randomized control trial examined miRNAs correlated with the early therapeutic effect of selective serotonin reuptake inhibitors (SSRIs; paroxetine or sertraline) and mirtazapine monotherapy. Before medication, we comprehensively analyzed the miRNA expression of 92 depressed participants and identified genes and pathways interacting with miRNAs. A total of 228 miRNAs were significantly correlated with depressive symptoms improvements after 2 weeks of SSRIs treatment, with miR-483.5p showing the most robust correlation. These miRNAs are involved in 21 pathways, including TGF-β, glutamatergic synapse, long-term depression, and the mitogen-activated protein kinase (MAPK) signaling pathways. Using these miRNAs enabled us to predict SSRI response at week 2 with a 57% difference. This study shows that pre-treatment levels of miRNAs could be used to predict early responses to antidepressant administration, a knowledge of genes, and an identification of genes and pathways associated with the antidepressant response.     

Continuous measurements of bronchial exposure induced by radon decay products during inhalation

The deposition of radon decay products is not equal in each of the respiratory regions and as the presence of radon has been linked with an increase in lung cancer risk, it is important to calculate the deposition of radon decay products in each of the respiratory regions. Recently, many studies on the deposition of radon in respiratory regions have been simulated using wire screens. The systems and equipment used in those studies are not suitable for field measurements as their dimensions are relatively massive, nor can they measure continuously. We developed a continuous bronchial dosimeter (CBD) which is suitable for field measurements. It was designed with specifications that allow it to be remain compact. The CBD simulates the deposition of radon decay products in the different respiratory regions by the use of a combination of wire screens. Deposition in the simulated regions of the lung can be continuously estimated in various environments. The ratio of activities deposited in a simulated nasal cavity (N) and tracheobronchial (TB) regions was calculated from the results of simultaneous measurements using CBD-R (reference), CBD-N (nasal), and CBD-TB (tracheobronchial) measurement units. After aerosols were injected into the radon chamber, the ratio of N and TB depositions decreased. This results indicate that the CBD gave a good response to changes in the environment. It was found that the ratio of N and TB deposition also varied with time in each actual environment.     

Effective cell-seeding technique using magnetite nanoparticles and magnetic force onto decellularized blood vessels for vascular tissue engineering

Increasing attention has been given to vascular tissue engineering in recent years. Although cell seeding onto tubular scaffolds is the first step for constructing three-dimensional vascular grafts, the tubular geometry of the grafts hinders the efficient delivery of cells onto the scaffold. To overcome these limitations, we present here a novel cell-seeding technique using magnetic force and magnetite nanoparticles, termed Mag-seeding. NIH/3T3 fibroblasts (3T3s) were labeled magnetically using our original magnetite cationic liposomes (MCLs), which have a positive surface charge, to improve adsorption onto cell surface. In this study, porcine decellularized common carotid artery (dCCA) was used as one of the most promising scaffolds, because dCCA consists of a mixture of structural and functional proteins that constitute the extracellular matrix. When a cylindrical magnet was inserted into the lumen of dCCA and the dCCA was immersed into a suspension of magnetically labeled 3T3s, almost all the 3T3s attached onto the dCCA, whereas a low cell-seeding efficiency was achieved without using a magnet. When the magnetite uptake rate per cell increased, cell-seeding efficiency by Mag-seeding was enhanced. Furthermore, to construct a vascular graft for humans, the porcine dCCA, which was reseeded with two human cells (smooth muscle cells and dermal fibroblasts), was successfully constructed by Mag-seeding. These results indicate that Mag-seeding can be used for vascular tissue engineering.     

Application of bis(fluorosulfonyl)imide-based ionic liquid electrolyte to silicon-nickel-carbon composite anode for lithium-ion batteries

An ionic liquid electrolyte containing bis(fluorosulfonyl)imide (FSI) anion without any solvent is applied to a silicon-nickel-carbon (Si-Ni-carbon) composite anode for rechargeable lithium (Li)-ion batteries. The FSI-based ionic liquid electrolyte successfully provides a stable, reversible capacity for the Si-Ni-carbon anode, which is comparable to the performance observed in a typical commercialized solvent-based electrolyte, while a common ionic liquid electrolyte containing bis(trifluoromethanesulfonyl)imide (TFSI) anion without FSI presents no reversible capacity to the anode at all. Ac impedance analysis reveals that the FSI-based electrolyte provides very low interfacial and charge-transfer resistances at the Si-based composite anode, even when compared to the corresponding resistances observed in a typical solvent-based electrolyte. Galvanostatic cycling of the Si-based composite anode in the FSI-based electrolyte with a charge limitation of 800 mAh g⁻¹ is stable and provides a discharge capacity of 790 mAh g⁻¹ at the 50th cycle, corresponding to a cycle efficiency of 98.8%.