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An experimental study was conducted to determine the threshold electrostatic field to initiate electrohydrodynamic jetting from a polymer solution droplet wetting on a conductive wire. The study is crucial to understand the roles of the material and process parameters in wire-based needleless electrospinning for controllable mass production of continuous nanofibers. Two types of polymer solutions, i.e., polyacrylonitrile/N,N-dimethylformamide (PAN/DMF) and aqueous polyethyloxide solution (PEO/H2O), with the mass concentrations of 4%, 8%, 12%, and 16% for PAN and 1%, 2%, 4%, 6%, and 8% for PEO, respectively, were considered in the experiments. Taut thin copper wires with diameters of 0.254, 0.508, 1.016, and 1.524 mm (i.e., 0.01, 0.02, 0.04, and 0.06 in.) were utilized, respectively, as the positive electrodes. The effects of the polymer concentration and wire diameter on the threshold electrical voltage for jetting initiation and nanofiber diameter were examined. Given the droplet volume and spacing between the copper wire and fiber collector, experimental observations show that the threshold electrical voltage increases with increasing either polymer mass concentration or wire diameter. In addition, the effects of polymer mass concentration on the transient shear viscosity and surface tension of the PAN/DMF solutions were examined. It shows the positive correlation between the transient shear viscosity and polymer mass concentration, shear thinning of the polymer solution at a high shear rate, and nearly constant surface tension of the polymer solution in the range of the present PAN mass concentration. Furthermore, a simple electrostatic model is formulated to phenomenologically elucidate the experimental observations. The present study provides useful scaling laws for controllable scale-up nanofiber fabrication by means of a wire-based needleless electrospinning technique. [ABSTRACT FROM AUTHOR]

The use of electrospun polystyrene (PS) fibers to create continuous long range ordered multi‐scale porous structures in titanium diboride (TiB2) is investigated in this work. The introduction of electrospun PS fibers as a sacrificial filler into a colloidal suspension of TiB2 allows for easy control over the pore size, porosity, and long range ordering of the porous structures of the sintered ceramics. Green bodies were formed by vacuum infiltrating an electrospun‐fiber‐filled mold with the colloidal TiB2 suspension. The size, volume, distribution, and dispersion of the pores were optimized by carefully selecting the sacrificial polymer, the fiber diameter, the solvent, and the solid content of TiB2. The green bodies were partially sintered at 2000°C to form a multi‐scale porous structure via the removal of the PS fibers. Aligned continuous cylindrical pores homogeneously distributed across the samples were derived from the PS fibers in a range of ~5‐20 μm and partial sintering produced inter‐particle porosity with sizes of ~0.3‐1 μm. TiB2 near‐net‐shaped parts with the multi‐scale porosities (~50‐70%) were successfully cast and sintered. This low‐cost processing technique can be used in the production of thermally and mechanically anisotropic structures into near‐net shape parts, for extreme environment applications, such as high temperature insulation. [ABSTRACT FROM AUTHOR]

This paper reports the fabrication and filtration characterization of advanced fibrous cellulose acetate (CA) membranes for high-flux water filtration. The ultrathin nonwoven fibrous CA membranes with varying fiber diameter and areal weight were produced by electrospinning and post-processed by hot-press. The filtration efficiency of the ultrathin fibrous CA membranes was characterized by controlled water-filtration tests based on artificial colloids prepared via dispersing polystyrene (PS) particles of the diameters of 5 μm, 2 μm, 500 nm, and 100 nm in water, respectively. Natural river water was further used for evaluating the filtration capability of the electrospun fibrous CA membranes. Experimental results show that the rejection rate of the present fibrous CA membranes to PS particles with the diameter of 2 μm was up to 99.8%. In addition, the filtration efficiency of the electrospun fibrous CA membranes increased with increasing areal weight of the membranes. In the case of the filtering electrospun fibrous CA membranes with the fiber diameter of ∼800 nm and membrane areal weight ∼0.005 g/cm 2 , the measured turbidity of natural river water after filtration can reach as low as 0.135 nephelometric turbidity unit (NTU) while the initial flow flux can reach up to 20,455 L/m 2 h at the feed pressure 14 psi. The study suggests that low-cost electrospun fibrous membranes can be used for stable, high-flux water microfiltration with the filtration efficiency. [ABSTRACT FROM AUTHOR]

Ultrathin superhydrophobic–superoleophilic fibrous poly (vinylidene fluoride) (PVDF) membranes were prepared by means of electrospinning technique for the purpose of low-cost, high-efficiency water–oil separation. The ultrathin electrospun fibrous PVDF membranes exhibited a high water contact angle up to 153° and nearly zero oil (diesel) contact angle. The surface morphology and hydrophobicity of the membranes can be conveniently tuned by adjusting the PVDF concentration of the electrospinning solutions. The obtained ultrathin fibrous PVDF membranes showed excellent performance in separation of water-in-oil emulsions. [ABSTRACT FROM AUTHOR]

Abstract: This paper reports the fabrication and electrochemical properties of novel high-performance pseudosupercapacitor electrodes made of graphene-beaded carbon nanofibers (G/CNFs) surface-coated with nanostructured conducting polymers. The G/CNFs were produced by electrospinning the precursor graphene-beaded polymer nanofibers, followed by controlled pyrolysis. In situ polymerization in aqueous solution was utilized to coat an ultrathin layer of thorn-like polyaniline (PANI) nanorods onto the G/CNFs to form ternary PANI-coated G/CNFs (PANI-G/CNFs). The highly porous network morphology of PANI-G/CNFs exhibited a very large specific surface area, low internal resistance, and fast redox rate. Electrochemical characterization indicated that the PANI-G/CNF based pseudosupercapacitors carried a high value of specific capacitance up to 637 F g−1 at a current density of 0.15 A g−1 and still maintained the high value of specific capacitance of 478 F g−1 (only 25% decrease) even at a high current density of 6 A g−1. The pseudosupercapacitor showed a very good cycling stability of 87% after 1000 charge/discharge cycles at a very high current density of 15 A g−1. The experimental results indicated that the novel hierarchical, porous PANI-G/CNFs are a promising electrode material for use in high-performance energy storage devices. [Copyright &y& Elsevier]

Key message: OsCOL5, an ortholog ofArabidopsis COL5, is involved in photoperiodic flowering and enhances rice yield through modulation ofGhd7andEhd2and interactions withOsELF3-1andOsELF3-2. Heading date, also known as flowering time, plays a crucial role in determining the adaptability and yield potential of rice (Oryza sativa L.). CONSTANS (CO)-like is one of the most critical flowering-associated gene families, members of which are evolutionarily conserved. Here, we report the molecular functional characterization of OsCOL5, an ortholog of Arabidopsis COL5, which is involved in photoperiodic flowering and influences rice yield. Structural analysis revealed that OsCOL5 is a typical member of CO-like family, containing two B-box domains and one CCT domain. Rice plants overexpressing OsCOL5 showed delayed heading and increases in plant height, main spike number, total grain number per plant, and yield per plant under both long-day (LD) and short-day (SD) conditions. Gene expression analysis indicated that OsCOL5 was primarily expressed in the leaves and stems with a diurnal rhythm expression pattern. RT-qPCR analysis of heading date genes showed that OsCOL5 suppressed flowering by up-regulating Ghd7 and down-regulating Ehd2, consequently reducing the expression of Ehd1, Hd3a, RFT1, OsMADS14, and OsMADS15. Yeast two-hybrid experiments showed direct interactions of OsCOL5 with OsELF3-1 and OsELF3-2. Further verification showed specific interactions between the zinc finger/B-box domain of OsCOL5 and the middle region of OsELF3-1 and OsELF3-2. Yeast one-hybrid assays revealed that OsCOL5 may bind to the CCACA motif. The results suggest that OsCOL5 functions as a floral repressor, playing a vital role in rice’s photoperiodic flowering regulation. This gene shows potential in breeding programs aimed at improving rice yield by influencing the timing of flowering, which directly impacts crop productivity. [ABSTRACT FROM AUTHOR]

Polymer electrolyte membrane fuel cells (PEMFCs) expect a promising future in addressing the major problems associated with production and consumption of renewable energies and meeting the future societal and environmental needs. Design and fabrication of new proton exchange membranes (PEMs) with high proton conductivity and durability is crucial to overcome the drawbacks of the present PEMs. Acid-doped polybenzimidazoles (PBIs) carry high proton conductivity and long-term thermal, chemical, and structural stabilities are recognized as the suited polymeric materials for next-generation PEMs of high-temperature fuel cells in place of Nafion® membranes. This paper aims to review the recent developments in acid-doped PBI-based PEMs for use in PEMFCs. The structures and proton conductivity of a variety of acid-doped PBI-based PEMs are discussed. More recent development in PBI-based electrospun nanofiber PEMs is also considered. The electrochemical performance of PBI-based PEMs in PEMFCs and new trends in the optimization of acid-doped PBIs are explored. [ABSTRACT FROM AUTHOR]

Key Message: TAC1is involved in photoperiodic and gravitropic responses to modulate rice dynamic plant architecture likely by affecting endogenous auxin distribution, which could explainTAC1widespread distribution in indica rice. Plants experience a changing environment throughout their growth, which requires dynamic adjustments of plant architecture in response to these environmental cues. Our previous study demonstrated that Tiller Angle Control 1 (TAC1) modulates dynamic changes in plant architecture in rice; however, the underlying regulatory mechanisms remain largely unknown. In this study, we show that TAC1 regulates plant architecture in an expression dose-dependent manner, is highly expressed in stems, and exhibits dynamic expression in tiller bases during the growth period. Photoperiodic treatments revealed that TAC1 expression shows circadian rhythm and is more abundant during the dark period than during the light period and under short-day conditions than under long-day conditions. Therefore, it contributes to dynamic plant architecture under long-day conditions and loose plant architecture under short-day conditions. Gravity treatments showed that TAC1 is induced by gravistimulation and negatively regulates shoot gravitropism, likely by affecting auxin distribution. Notably, the tested indica rice containing TAC1 displayed dynamic plant architecture under natural long-day conditions, likely explaining the widespread distribution of TAC1 in indica rice. Our results provide new insights into TAC1-mediated regulatory mechanisms for dynamic changes in rice plant architecture. [ABSTRACT FROM AUTHOR]

Grain shape improvement, which determines grain yield, quality traits and commercial value, is an extremely important aspect of rice breeding. Grain size is controlled by multiple genes, and Maker Assistant Selection (MAS) breeding is effective for breeders in developing stable and efficient markers to aggregate these genes in order to speed up the selection of new lines with desirable traits during the breeding process. In this study, functional markers were developed based on the sequence differences of five grain-shaped genes (GL7, GW6a, GS6, GW5 and TGW6) between the long-grain japonica rice variety Zhendao and the indica-japonica restorer R2027. We then constructed a population of recombinant inbred lines (RILs) based on their cross. The newly designed functional markers were used to genotype grain-size genes, and a genetic effect analysis was conducted to screen high-quality long-grain restorers. Our results reveal diverse effects of different genes on grain size, and the five genotypes were distributed in the 36 selected BC1F8 lines. Specifically, gw5 positively regulates grain width and 1000-grain weight, gl7 and gs6 positively regulate grain length but negatively regulate grain width and 1000-grain weight, tgw6 positively regulates grain length and gw6a positively regulates 1000-grain weight. The most outstanding outcome is that 5 of the 36 lines achieved in this study showing an excellent performance of long grain and yield characters are ideal materials not only for studying the interaction and genetic effects between polygenes but also as restorers or donors for dominant genes in indica-japonica hybrid rice breeding. [ABSTRACT FROM AUTHOR]

A simple, first-principles mathematical model has been developed to analyze the effect of interfacial and bulk charge transfer on the power output characteristics of dye-sensitized solar cells (DSSCs). Under steady state operating conditions, the Butler-Volmer equation and Schottky barrier model were applied to evaluate the voltage loss at counter electrode/electrolyte and TiO2/TCO interfaces, respectively. Experimental data acquired from typical DSSCs tested in our laboratory have been used to validate the theoretical J-V characteristics predicted by the present model. Compared to the conventional diffusion model, the present model fitted the experimental J-V curve more accurately at high voltages (0.65-0.8 V). Parametric studies were conducted to analyze the effect of series resistance, shunt resistance, interfacial overpotential, as well as difference between the conduction band and formal redox potentials on DSSCs’ performance. Simulated results show that a “lower-limit” of shunt resistance (103 Ωcm2) is necessary to guarantee a maximized efficiency. The model predicts a linear relationship between open circuit voltage (Voc) and photoanode temperature (T) with a slope of −1 mV/°C, which is close to the experimental data reported in literature. Additionally, it is observed that a small value of overpotential (2.2 mV) occurs at the short-circuit condition (Jsc = 10.5 mA/cm2), which is in a close agreement with Volmer-Butler equation. This observation suggests that, compared to the maximum attainable voltage (700 mV), the overpotential values are small and can be neglected for platinum catalyst based DSSCs. [ABSTRACT FROM AUTHOR]

Dye-sensitized solar cell (DSSC) offers an efficient and easily implemented technology for future energy supply. Compared to conventional silicon solar cells, it provides comparable power conversion efficiency (PCE) at low material and manufacturing costs. DSSC materials such as titanium oxide (TiO 2 ) are inexpensive, abundant and innocuous to the environment. Since DSSC materials are less prone to contamination and processable at ambient temperature, a roll-to-roll process could be utilized to print DSSCs on the mass production line. DSSCs perform better under lower light intensities, which makes them an excellent choice for indoor applications. Due to the advancement of molecular engineering, colored and transparent thin films have been introduced to enhance the aesthetic values. Up to now, such benefits have attracted considerable research interests and commercialization effort. Here, this review examines advanced techniques and research trends of this promising technology from the perspective of device modeling, state-of-art techniques, and novel device structures. [ABSTRACT FROM AUTHOR]

A simple dry physical grinding and solvent mixing approach was used to prepare tin selenide – multiwalled carbon nanotube (MWCNT) hybrid as an anode material for high performance lithium ion batteries (LIBs). The pure tin selenide and their composites with carbon black or graphene oxides were previously reported, however no other groups have reported tin selenide/MWCNT composite as anode materials for LIBs. The new hybrid had superior electrochemical cycling performance with higher reversible (lithiation) capacity of 882 to 651 mA hg −1 over 50 cycles compared to pure tin selenide (602 to 58 mAhg −1 ) or pure MWCNT (339 to 171 mAhg −1 ) electrodes. The enhanced performance of the tin selenide/MWCNT hybrid was attributed to various factors including alleviation of volume change of tin selenide during lithiation/delithiation by nanoscale network of MWCNT which helped to preserve the electrical connectivity between active particles, reversible decomposition of tin selenide, lithiation/delithiation of MWCNTs and conductive electronic transport pathways provided by MWCNTs. [ABSTRACT FROM AUTHOR]

Titanium carbides are well-known for their outstanding mechanical and thermal stabilities. However, the studies on the mechanical properties and the conductivity of titanium carbide–carbon nanofibers (TiC/CNF) are missing. This work prepared TiC/CNF by electrospinning and highlighted the high modulus of single TiC/CNF, the flexibility and the excellent electrical conductivity of TiC/CNF felt even under 100 bending cycles. This flexible TiC/CNF felt with distinguished mechanical and electrical properties are promising to apply in titanium matrix composites (TMC), efficient catalyst scaffolds and electronic devices. [ABSTRACT FROM AUTHOR]