Electrically conductive hydrogels (ECHs), combining electrical properties of metals or semiconductors with the unique features of hydrogels, are ideal frameworks to design and construct flexible supercapacitors and batteries. This review summarized the material design and synthetic approach of ECHs, demonstrating the advances of percolation theory in ECH materials, followed by presenting their effective application in flexible energy storage systems, and discussed the challenges and opportunities in this field.

A new class of solution-processable polymer semiconductors, poly(2,6-bis(3-alkylthiophen-2-yl)dithieno[3,2-b;2′,3′-d]thiophene)s, has been synthesized by Stille coupling polymerization of 2,6-bis-trimethyl-stannanyl-dithieno[3,2-b;2′,3′-d]thiophene with 5,5′-dibromo-4,4′-dialkyl-[2,2′]bithiophene in good yields. In thin-film transistors, this polymeric semiconductor has exhibited high field-effect mobility (0.3 cm2/(V s)) and high current on/off ratio (107) when the devices are fabricated and characterized entirely in ambient conditions.

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SummaryWild-type Anabaena sp. strain PCC 7120, a filamentous nitrogen-fixing cyanobacterium, produces single heterocysts at semi-regular intervals. asr0100 (patU5) and alr0101 (patU3) are homologous to the 5Ј and 3Ј portions of patU of Nostoc punctiforme. alr0099 (hetZ) overlaps the 5Ј end of patU5. hetZ, patU5 and patU3 were all upregulated, or expressed specifically, in proheterocysts and heterocysts. Mutants of hetZ showed delayed or no heterocyst differentiation. In contrast, a patU3 mutation produced a multiple contiguous heterocyst (Mch) phenotype and restored the formation of otherwise lost intercalary heterocysts in a patA background. Decreasing the expression of patU3 greatly increased the frequency of heterocysts in a mini-patS strain. Two promoter regions and two principal, corresponding transcripts were detected in the hetZ-patU5-patU3 region. Transcription of hetZ was upregulated in a hetZ mutant and downregulated in a patU3 mutant. When mutants hetZ::C.K2 and hetZ::Tn5-1087b were nitrogen-deprived, P hetC-gfp was very weakly expressed, and in hetZ::Tn5-1087b, PhetR-gfp was relatively strongly expressed in cells that had neither a regular pattern nor altered morphology. We conclude that the hetZ-patU5-patU3 cluster plays an important role in co-ordination of heterocyst differentiation and pattern formation. The presence of homologous clusters in filamentous genera without heterocysts is suggestive of a more general role.

Minimizing adhesion of ice has been the subject of extensive studies because of importance to applications such aircraft wings, spacecraft, and power transmission wires. A growing interest concerns coatings for wind turbine blades and refrigeration. Herein, a new laboratory test was employed to obtain the thickness dependence of ice adhesion for Sylgard 184-a filled polydimethylsiloxane elastomer. A correlation between ice adhesion and coating thickness (t) was found that follows a relationship developed by Kendall over 40 years ago for removal of a rigid object from an elastomer. With a 0.05 mm/s probe speed a nearly linear relationship between peak removal stress (Ps) and 1/t(1/2) was obtained with Ps ∼ 460 kPa for an 18 μm coating, decreasing to ∼120 kPa for 533 μm. Preliminary results suggest that below ∼10 μm Ps departs from the 1/t(1/2) correlation while above ∼500 μm a limiting value for Ps may be reached. We previously reported that probe speed has negligible effect on the glassy polymer PMMA. In contrast, probe speed is identified as an important variable for testing ice release on elastomeric Sylgard 184 coatings. While work of adhesion, which is related to surface free energy, is recognized as an important factor that can affect ice release, the results reported herein show that coating thickness can override this single parameter for elastomeric substrates.

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Degradation at the electrode surfaces is one of the major reasons behind capacity fade in well-constructed batteries. The effect of electrolyte additives, in particular vinylene carbonate (VC), is studied extensively for different lithium-ion chemistries and is shown to improve columbic efficiency of some electrodes. We investigate the effect of VC additive in a graphite/NMC333 (lithiumnickel-manganese-cobalt oxide) cell. The addition of VC improves the rate performance, especially, at moderately high rates. A new three-electrode cell design with Li reference electrode was particularly useful in studying the rate performance of each electrode. The rate of side reactions is found to decrease with the addition of VC. Despite these important performance improvements, no significant improvement in the capacity retention is observed. This suggests that the side reactions in graphite/NCM cells consist of two types, (1) repairing cracked solid electrolyte interphase (SEI) on the negative electrode (results in a net consumption of Li from the positive electrode), (2) reforming SEI components that dissolve from the negative electrode and are oxidized at the positive electrode. The VC appears to reduce the second type but have negligible effect on the first. This indicates that columbic efficiency measurements are not a reliable indicator of cell cycle life. Electrode side reactions are one of the major reasons for the loss of performance of Li-ion batteries. The instability of commonly used electrolytes at typical operating potentials results in side reactions, some of which go to solid electrolyte interphase (SEI) formation at electrode surfaces.1-4 Using electrolyte additives is one effective way to minimize the rate of chemical degradation. Electrolyte additives also may be used to form a thinner, more compact and stable SEI, and thus reduce irreversible capacity loss, reduce parasitic reactions, and improve thermal stability of LiPF 6 salt against the electrolyte solvents. Zhang et al.5 nicely summarize different electrolyte additive studies in the literature classifying them by their SEI stabilization mechanism. In lithium ion batteries, electrolyte additives tend to affect two aspects of cell characteristics, namely, cell impedance and side reactions. In the present work the effect of Vinylene carbonate (VC) on both of these parameters was studied. In the first part of this article, the effect of electrolyte additive on the impedance of the individual electrodes using 3-electrode cell is illustrated. The second part correlates the effect of VC on cell side reactions and coulombic efficiency. This study was useful to demonstrate our hypothesis that coulombic efficiency is not a reliable indicator of cell cycle life.Vinylene carbonate (VC) has been extensively studied as an electrolyte additive and shown to improve battery life in some lithiumion battery chemistries.6 Aurbach et al. 1 observed a reduction of the impedance of synthetic graphite flakes, LiNiO 2 , and LiMn 2 O 4 electrodes against lithium counter electr...

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