Ammonia-Assisted Wet-Chemical Synthesis of ZnO Microrod Arrays on Substrates for Microdroplet Transfer

It is still a challenging task to facilely grow microscale arrays on arbitrary substrates at low temperature conditions in solutions. Here, we have successfully formed ZnO microrod arrays on various substrates, including glass, gold coated glass, silicon wafer, and Teflon, by a single-step wet-chemical synthesis approach. We employ ammonia as the multifunctional reactant to modify the surface properties of the substrates and to regulate the pH of the reaction environment. Compared to other methods, no preloaded additives or seeds are required. The surface wettability of the ZnO microrod coated substrates can be tuned, achieving both hydrophilic and hydrophobic properties in air. We have studied both static wettability and dynamic behaviors of droplet impact or rebound on the modified substrates. We demonstrate that it is possible to achieve micromass transfer by using the hydrophobic substrate to repel water microdroplet while using the hydrophilic substrate to capture the water microdroplets utilizing their different dynamic wettability-induced responses to water droplets. We believe that the ZnO microrod array coated substrates with different static/dynamic wettability may find many potential applications, such as antiwetting, self-cleaning, inject printing, micromass transfer and capture, biomedical diagnosis, microanalysis, and so forth

Amorphous Bimetallic Co₃Sn₂ Nanoalloys Are Better Than Crystalline Counterparts for Sodium Storage

Sodium-ion batteries are considered as a promising alternative to replace the existing lithium-ion batteries for energy storage due to the benefits of low cost and safety. However, it is still challenging to develop suitable electrode materials for reversible storage of sodium. Metal anodes have high capacity for sodium storage but suffer the issue of poor cyclability due to pulverization caused by large volume variation and electrode disintegration. To address this issue, amorphous bimetallic active–inactive nanoalloy Co–Sn with Sn acting as a high capacity active compound and Co acting as a conductive inactive matrix has been explored here. We demonstrated that amorphous nanoalloys exhibited superior electrochemical performances as compared to the low-crystalline and crystalline counterpart nanoalloys as negative electrode materials for sodium-ion batteries. The degree of crystallinity has negative effects on electrochemical performances. The improved performance of amorphous nanoalloys could be attributed to the easy accessibility for sodium ions, strain accommodation, and defect sites to host sodium ions

Convergence Properties of a Sequential Regression Multiple Imputation Algorithm

<div><p>A sequential regression or chained equations imputation approach uses a Gibbs sampling-type iterative algorithm that imputes the missing values using a sequence of conditional regression models. It is a flexible approach for handling different types of variables and complex data structures. Many simulation studies have shown that the multiple imputation inferences based on this procedure have desirable repeated sampling properties. However, a theoretical weakness of this approach is that the specification of a set of conditional regression models may not be compatible with a joint distribution of the variables being imputed. Hence, the convergence properties of the iterative algorithm are not well understood. This article develops conditions for convergence and assesses the properties of inferences from both compatible and incompatible sequence of regression models. The results are established for the missing data pattern where each subject may be missing a value on at most one variable. The sequence of regression models are assumed to be empirically good fit for the data chosen by the imputer based on appropriate model diagnostics. The results are used to develop criteria for the choice of regression models. Supplementary materials for this article are available online.</p></div

Local Dielectric Environment Dependent Local Electric Field Enhancement in Double Concentric Silver Nanotubes

The local dielectric environment dependent local field enhancement properties in double concentric silver nanotubes have been obtained by using the plasmon hybridization method and quasi-static calculation. Because of the inserted silver nanotube, the geometrical parameter controlled intertube coupling greatly improves the tunability of the local dielectric dependent enhancement of local electric field. In the inner dielectric core, the most intense local field factor peak corresponds to the |ω_–⁺⟩ plasmon mode, and the major local field factor peak usually changes nonmonotonously as the inner core or spacer layer dielectric is increased. The maximum local field could be obtained by fine-tuning the local dielectric constant in the double tubes with thick inner and outer tube thickness. In the dielectric spacer layer, the most intense local field factor peak corresponds to the |ω_–^–⟩ plasmon mode. The intense local field could be obtained with small spacer layer dielectric constant and reaches the maximum value when the double tube has thick inner and outer tube thickness. This inner core and spacer layer dielectric dependent local field enhancement provides the potential application of the real time tubular nanosensor based on local field induced fluorescence enhancement and surface-enhanced Raman scattering (SERS)

Hollow Cocoon-Like Hematite Mesoparticles of Nanoparticle Aggregates: Structural Evolution and Superior Performances in Lithium Ion Batteries

We report the facile, fast, and template-free preparation of hollow α-Fe₂O₃ with unique cocoon-like structure by a one-pot hydrothermal method without any surfactants in a short reaction time of 3 h only. In contrast, typical hydrothermal methods to prepare inorganic hollow structures require 24 h or a few days. Templates and/or surfactants are typically used. The hollow α-Fe₂O₃ nanococoon was thoroughly characterized by field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). Ex situ analysis of a series of samples prepared at different reaction times clearly revealed the structural evolution and possible formation mechanism. Superior electrochemical performance in terms of cyclability, specific capacity, and high rate was achieved, which could be attributed to its unique hollow cocoon-like structure. Structural stability was revealed by analyzing the samples after 120 charge–discharge cycles. The unusual structural stability of the hollow α-Fe₂O₃ nanococoons after 120 cycles, which is rarely observed for transition metal oxides of particle aggregates, will guarantee further research investigation. Experimental evidence further demonstrated that hollow nanococoons exceed solid nanococoons in reversible lithium-ion storage

Micro Single Crystals of Hematite with Nearly 100% Exposed {104} Facets: Preferred Etching and Lithium Storage

The controlled synthesis of inorganic single crystals with a large percentage of exposed high-index facets has attracted much attention. However, high-index facets usually disappear during the early stage of crystal growth due to the minimization of surface energy and typically facet-controlling agents are employed. Here a facile fast hydrothermal method for the preparation of microsize α-Fe₂O₃ rhombohedra with nearly 100% exposed {104} facets was developed in a simple formulated solvent without any additives. The hydrothermal reaction time could be as short as 75 min, in contrast to typical hydrothermal reactions over days. The preferred etching edges along the diagonal axis of microsize rhombohedra by the self-generated ions was observed, which could be potentially extended to synthesize and tailor other transition metal oxides. The formation mechanism was revealed by ex situ FESEM observations of the samples prepared at different reaction times. Improved electrochemical performances in terms of cyclability, specific capacity, and high rate were achieved. The specific capacity was maintained at 550 mAh/g after 120 cycles at a rate of 200 mA/g. Experimental evidence clearly shows that the as-designed solid microsize α-Fe₂O₃ can effectively and reversibly store lithium ions with performance comparable to nanosize α-Fe₂O₃, suggesting electrode materials with particle size at the microscale will be worth further exploration

Development and Structure of Internal Glands and External Glandular Trichomes in <i>Pogostemon cablin</i>

<div><p><i>Pogostemon cablin</i> possesses two morphologically and ontogenetically different types of glandular trichomes, one type of bristle hair on the surfaces of leaves and stems and one type of internal gland inside the leaves and stems. The internal gland originates from elementary meristem and is associated with the biosynthesis of oils present inside the leaves and stems. However, there is little information on mechanism for the oil biosynthesis and secretion inside the leaves and stems. In this study, we identified three kinds of glandular trichome types and two kinds of internal gland in the <i>Pogostemon cablin</i>. The oil secretions from internal glands of stems and leaves contained lipids, flavones and terpenes. Our results indicated that endoplasmic reticulum and plastids and vacuoles are likely involved in the biosynthesis of oils in the internal glands and the synthesized oils are transported from endoplasmic reticulum to the cell wall via connecting endoplasmic reticulum membranes to the plasma membrane. And the comparative analysis of the development, distribution, histochemistry and ultrastructures of the internal and external glands in <i>Pogostemon cablin</i> leads us to propose that the internal gland may be a novel secretory structure which is different from external glands.</p></div

Plant Uptake-Assisted Round-the-Clock Photocatalysis for Complete Purification of Aquaculture Wastewater Using Sunlight

A novel reactor equipped with solar batteries, Bi₂O₃/TiO₂ film photocatalyst, and celery plant was designed and used for purification of aquaculture wastewater. The Bi₂O₃/TiO₂ film photocatalyst started photocatalytic degradation of organonitrogen compounds under irradiation of sunlight. Meanwhile, the solar batteries absorbed and converted excess sunlight into electric energy and then started UV lamps at night, leading to round-the-clock photocatalysis. Subsequently, the inorganic nitrogen species including NH₄⁺, NO₂^–, and NO₃^– resulting from photocatalytic degradation of the organonitrogen compounds could subsequently be uptaken by the celery plant as the fertilizer to reduce the secondary pollution. It was found that, after 24 h circulation, both organonitrogen compounds and NO₂^– species were completely removed, while NH₄⁺ and NO₃^– contents also decreased by 30% and 50%, respectively. The reactor could be used repetitively, showing a good potential in practical application

X‑ray Crystal Structure of Phosphodiesterase 2 in Complex with a Highly Selective, Nanomolar Inhibitor Reveals a Binding-Induced Pocket Important for Selectivity

To better understand the structural origins of inhibitor selectivity of human phosphodieasterase families (PDEs 1–11), here we report the X-ray crystal structure of PDE2 in complex with a highly selective, nanomolar inhibitor (BAY60-7550) at 1.9 Å resolution, and the structure of apo PDE2 at 2.0 Å resolution. The crystal structures reveal that the inhibitor binds to the PDE2 active site by using not only the conserved glutamine-switch mechanism for substrate binding, but also a binding-induced, hydrophobic pocket that was not reported previously. <i>In silico</i> affinity profiling by molecular docking indicates that the inhibitor binding to this pocket contributes significantly to the binding affinity and thereby improves the inhibitor selectivity for PDE2. Our results highlight a structure-based design strategy that exploits the potential binding-induced pockets to achieve higher selectivity in the PDE inhibitor development

X‑ray Crystal Structure of Phosphodiesterase 2 in Complex with a Highly Selective, Nanomolar Inhibitor Reveals a Binding-Induced Pocket Important for Selectivity

To better understand the structural origins of inhibitor selectivity of human phosphodieasterase families (PDEs 1–11), here we report the X-ray crystal structure of PDE2 in complex with a highly selective, nanomolar inhibitor (BAY60-7550) at 1.9 Å resolution, and the structure of apo PDE2 at 2.0 Å resolution. The crystal structures reveal that the inhibitor binds to the PDE2 active site by using not only the conserved glutamine-switch mechanism for substrate binding, but also a binding-induced, hydrophobic pocket that was not reported previously. <i>In silico</i> affinity profiling by molecular docking indicates that the inhibitor binding to this pocket contributes significantly to the binding affinity and thereby improves the inhibitor selectivity for PDE2. Our results highlight a structure-based design strategy that exploits the potential binding-induced pockets to achieve higher selectivity in the PDE inhibitor development