We present droplet manipulation using a digital microfluidic device comprising downward electrodes. Using this device, we demonstrated droplet transportation, programmable dispensing, and droplet coalescence without existing technical constraints on droplet manipulation. This device is expected to be useful for droplet-based multi-content screening and high-throughput screening in the field of analysis and synthesis.
In this paper, phase behavior, ionic conductivity, and current-voltage response were evaluated for gels consisting of imogolite nanotubes crosslinked by dicarboxylic acid in ionic liquid to obtain knowledge for designing their physical and electrochemical properties. The phase behavior and ionic conductivity of the gels vary depending on structure of dicarboxylic acid and polarity of solvent. Furthermore, definite current response of the gel was confirmed against voltage application.
To show that artifacts can readily form during research on marine natural products, a common marine sesquiterpenoid 1 was treated with sunlight in the presence of a pigment. Another set of solutions were prepared and kept in shade under the bench for two weeks as negative controls. As a result, four oxygenated derivatives 2–5 were obtained. A unique structure of a highly oxidized molecule 5 was solved by X-ray crystallography.
The electronic and chemical properties of ZnO surfaces are greatly affected by the adsorption of H atoms. The interaction of H atoms with ZnO(0001) and ZnO(000-1) surfaces has been investigated by temperature programmed desorption (TPD) methods. When the ZnO(000-1) surface is exposed to atomic H at 200 K, one desorption peak of H2 is observed at 455 K (α-peak). In the case of ZnO(0001), two desorption peaks of H2 are observed at 255 K (γ-peak) and 455 K (α-peak). As H exposure increases, the intensity of the γ-peak increases as the α-peak is attenuated. The α-peak is assigned as the hydrogen adsorbed on O-sites and the γ-peak is attributed to hydrogen adsorbed on Zn clusters on ZnO. Zn clusters are produced only on the ZnO(0001) surface as surface O-H bonds are formed.
Ligands which incorporate second-sphere intramolecular hydrogen bonding show potential for enhancing selectivity and binding strength for beryllium. In this highlight review, recent advances in the design of tetradentate ligands to selectively bind beryllium are discussed, as is the use of electrospray ionization mass spectrometry (ESI-MS) and 9Be nuclear magnetic resonance (NMR) spectroscopy as tools for the analysis of beryllium coordination compounds.
In this study, we used a CdSe/ZnS core/shell quantum dot (QD) as a fluorescent probe and developed a quantum dot-based fluorescence-linked immunosorbent assay (QD-FLISA) to quantitatively determine procalcitonin (PCT) levels in samples. The QD-antibody probe had a high fluorescent intensity and excellent stability, which met the needs of commercial fluorescent probe materials. Due to the excellent properties of clinical testing for PCT, this QD-FLISA method showed tremendous potential for use in in vitro diagnostic (IVD) kits.
We report a versatile method for preparing a particulate composite based on cellulose nanocrystals (CNCs) and polyethylene glycol (PEG) via a self-organized precipitation method. The particulate composite had a core–shell structure, and depending on the molecular weight of the PEG, two types of particulates could form: one with CNCs as the core and the other with CNCs as the shell.
Herein, we succeeded in reproducibly synthesizing palladium nanoparticles with narrow size distribution inside metal–organic frameworks (MOFs) by using pressured H2 gas as a reductant. In addition, by controlling the crystallinity of the MOFs, the particle size could be precisely controlled.
Surface-enhanced Raman spectroscopy (SERS) utilizes Au nanostructured surfaces where it demonstrates significant enhancement properties due to the localized surface plasmon phenomena. Here we systematically fabricated homogeneous polyvinylpyrrolidone (PVP)-stabilized Au nanostars while controlling size and apex shape with the molecular weight of PVP, so as to elucidate the correlation between structural and optical properties of nanostars. The highest sensitivity of SERS measurements realized in this study reached 26 times higher enhancement than that with conventional Au nanoparticles with a diameter of 55 nm.
Oriented chitosan films, prepared by elongation, are applied to a surface wrinkling system via a horseradish peroxidase-catalyzed surface reaction of ferulic acid and drying. The wrinkle morphologies of the obtained films are strongly affected by drying compression stress inverse to the elongation direction, probably caused by an entropic spring. The most oriented chitosan film elongated until a fracture strain showed a herringbone-like pattern produced by parallel and orthogonal compression stresses to the orientation direction.
We present an electrodeposition method for fabricating thiolated polymer-based hydrogels through oxidation of hydroquinone (HQ). HQ is oxidized to benzoquinone (BQ) at an electrode, and the generated BQ is utilized for disulfide formation through an electrocatalytic reaction. As a simple demonstration of bioapplications, an electrodeposited hydrogel containing glucose oxidase was applied for glucose sensing. To the best of our knowledge, this is the first report on the electrodeposition of thiolated polymer-based hydrogels via disulfide formation using the indirect approach.
The superhydrophobic-conductive anti-corrosion mode has attracted much more attention due to the huge economic losses of stainless steel corrosion. Here, a brand-new strong superhydrophobic-conductive polyaniline-polysiloxane (PANIC-RA-POS) anti-corrosion coating was prepared. The internal conductive and dense interpenetrating network polyaniline layer can effectively reduce electrochemical corrosion, the external superhydrophobic polysiloxane layer can effectively decrease chemical corrosion, the adhesive layer obviously improves the binding force of polyaniline and polysiloxane layer, and furthermore, it has excellent protection efficiency, corrosion durability and binding force.
A rotating gliding arc (RGA) reactor was investigated for conversion of multiple model tar compounds including toluene, naphthalene, and phenol in simulated synthetic gas, with special focus on the effects of steam concentration (0–20%) and preheating temperature (300–700 °C). The maximum conversions of toluene, naphthalene, and phenol were 89.3%, 84.6% and 95.5%, respectively, at a steam concentration of 12% and a preheating temperature of 500 °C. The tar conversion reaction facilitated the formation of fuel gas H2 and CO and reduced the CH4 and CO2 content, thus increasing the heating value of the simulated synthetic gas, by a maximum of 5.1% at a steam concentration of 20%. The results indicated that the RGA plasma is promising for achieving efficient conversion of tar of complex composition in high temperature simulated synthetic gas and upgrading gaseous products.
In this manuscript, we will illustrate a new idea for narrowing energy gaps between frontier molecular orbitals (FMOs) by selectively perturbing the levels of highest occupied molecular orbitals (HOMOs) and/or lowest unoccupied molecular orbitals (LUMOs). Initially, the basic concept of the isolated FMOs is explained by employing pentaazaphenalene (5AP) derivatives. It was found that electronic structures of the isolated LUMO of 5AP can be preserved even when incorporated into polymer chains if the connecting points are separated from the isolated LUMO. The mechanism and their unique electronic properties are summarized. Next, conversely, isolated HOMO and LUMO can be perturbed by conjugation effects independently. On the basis of this fact, near infrared (NIR)-absorbing molecules can be obtained by selectively elevating HOMO and lowering LUMO energy levels. We also mention strategies for enhancing luminescent properties of 5AP derivatives. Finally, we demonstrate that the isolated LUMO can be found in commodity luminescent dyes, such as boron dipyrromethene (BODIPY). By selectively lowering the LUMO energy level through the aza-substitution at the skeletal carbon where the isolated LUMO is distributed, NIR-emissive polymers can be obtained. Versatility of the isolated FMOs for obtaining optoelectronic organic materials is explained in this review.
Nitric oxide (NO) is generated in some biological systems. Due to its radical character, it exhibits high reactivity, but biological system can manage NO without sustaining any damage to bio-compounds in the cell. As a model system to understand how the NO dynamics is controlled in the cell, we have been studying denitrification of microbial respiration, in which NO is generated as an intermediate product. In denitrification, it was found that NO produced by the NO-generating enzyme (NiR: nitrite reductase) can be smoothly transferred to the NO-decomposing enzyme (NOR: nitric oxide reductase) by making a complex of the two enzymes. The chemical mechanism of the NO decomposition by NOR was also revealed by the time-resolved spectroscopic techniques.
Silylative dearomatizations of indole-2-carboxylates were accomplished using a copper(I) catalyst and silylboronates. This reaction presumably proceeds through regioselective addition of silylcopper(I) species to indole substrates followed by highly diastereoselective protonation of the resulting copper(I) enolate intermediates to afford the corresponding dearomative silylation products. The first silylative dearomatization of pyrroles using the developed catalytic system is also described.
A cyclic (alkyl)(amino)bromoborane (CAABBr) was synthesized by a reaction of the corresponding hydroborane with bromine in the presence of triethylamine. Reduction of the resulting CAABBr with Li powder and 4,4′-di-tert-butylbiphenyl (DBB) generated a thermally labile cyclic (alkyl)(amino)boryllithium (CAABLi) which was characterized by NMR spectroscopy. Quenching of the mixture reduced by Li/DBB with methanol-d1 or MeOTf at low temperature gave a deuterioborane or methylborane, supporting the generation of CAABLi.
Microscopic studies on electrolyte solution/electrode interfaces provide the most fundamental information not only for understanding the electric double layer formed at the interfaces but also for designing sophisticated electrochemical devices. Various types of in situ techniques, performed without taking the electrode out of electrolyte solutions, have become indispensable tools. Among them, electrochemical tip-enhanced Raman spectroscopy (EC-TERS) is considered as an ultimate tool because of simultaneous measurements of electrochemical scanning tunneling microscopy (EC-STM) and Raman spectroscopy just underneath the EC-STM tip. On the other hand, ex situ techniques, where the electrode is emersed from the solution to perform precise measurements, have been still useful because the detailed information not easy to obtain by in situ techniques is available just by combining conventional instruments, such as photoelectron spectroscopy (PES) for the analysis of electronic states. In this highlight review, we present our recent progresses with in situ (EC-TERS) and ex situ (PES combined with electrochemistry) experiments for elucidating the microscopic properties of electric double layers. Current issues and future perspective of both techniques are also discussed in detail.
Exfoliation of layered materials provides nanosheets, such as monolayers and few-layers. In recent years, nanosheets have attracted much interest as two-dimensional (2D) materials for their diverse properties and applications originating from the anisotropic characteristic structures. Exfoliation methods have been developed depending on the types of interactions between the layers, such as van der Waals and electrostatic interactions. The present review focuses on exfoliation chemistry based on rigid and soft natures of the layered materials. The rigid inorganic layered compounds are converted to the soft layered materials with interaction of organic guests. The surface-functionalized nanosheets are obtained by exfoliation of the soft layered composites with dispersion in organic media. The exfoliation behavior is governed by the flexibility of the precursor layered materials, i.e. interaction between the interlayer guest and dispersion medium. Although exfoliation is generally an uncontrollable top-down process, materials informatics on our own experimental small data assists elucidation of the control factors toward tailored 2D materials. The exfoliation schemes are applied to a variety of layered materials. The present review shows potential new insights for exfoliation chemistry of soft layered materials.
A 14N and 1H NMR spectroscopic study was carried out to shed light on microscopic aspects of the reaction of model alkylamines at a supercritical temperature of 400 °C. It is disclosed that NH3 and ROH (R = CH3CH2 and CH3 (CH2)3) are initially produced from the hydrolysis of ethylamine and butylamine, respectively. When the water density is doubled from 0.2 g cm−3, the pseudo-first-order reaction rate is markedly enhanced beyond the linear response. It suggests that the transition state of the C-N bond cleavage is in a dipolar (ionic) state that can be more stabilized due to the many-body solvation by highly polar water molecules at a higher density.
A wide variety of synthetic molecular machines has been designed and synthesized to construct nanometer-scale assemblies whose molecular motions can be precisely controlled by external stimuli. A helical structure is one of the most intriguing structural motifs to realize such molecular machines, because of its unique spring-like shape that enables reversible extension and contraction motions. This short review highlights the recent progress in the synthesis, structures, and functions of synthetic molecular springs based on single- and multi-stranded helical structures.
Cu/Zn-superoxide dismutase (SOD1) is a metalloenzyme that catalyzes the disproportionation of superoxide. This review summarizes intracellular processes for metal binding and disulfide formation in SOD1, both of which are essential to stabilization of the protein structure as well as its enzymatic function. Also, failure of those processes as a possible cause of a neurodegenerative disease through protein misfolding will be described.
Electrolytic deoxygenation devices have been fabricated using SiC, SWCNT, graphene, and PEDOT*PSS for the electrodes. Characteristics of devices were studied by measuring currents, O2 and H2 concentrations, and humidity during deoxygenation in a closed container. Performances of the devices being composed of cation or anion exchange membrane are discussed comparing with the standard catalyst of Pt-black. It is found that generation of moisture and H2 was substantially involved in the deoxygenation.
The PdAu random alloy nanoparticle catalyst shows excellent catalytic activity for heterogeneous molecular formations, whereas monometallic Pd or Au catalysts were ineffective. The Pd/Au ratio in the alloy had a significant impact on its catalytic performance, and the catalyst with a low Pd concentration exhibited excellent activity. The concerted catalysis of Pd and Au adjacent on the alloy surface is responsible for the specific catalytic performance.
Ferredoxin is a type of electron carrier protein involved in many biological redox reactions and also incorporated as an electron transfer domain and subunit in redox enzyme complexes. MvhB-type polyferredoxin is an iron-sulphur protein composed of three to seven 2[4Fe-4S]-ferredoxin domains. In this short review, we introduce the structure and function of MvhB-type polyferredoxin modules in methanogenic enzymes and then discuss the possible physiological function of the putative MvhB-like polyferredoxins identified in microbial genomes.
Inorganic nanoparticles are an attractive material that shows unique properties that differ from their bulk counterparts. Assembly of nanoparticles with soft materials is an effective approach to leverage their unusual properties for the fabrication of functional devices. Among the various soft materials, polymer brushes are expected to offer exciting opportunities due to their unique conformational properties. Here, we review research progress in the assembly and active control of gold nanoparticles with polymer brushes as a scaffold.
In this study, chiral guanidine catalyzed acylative kinetic resolution of racemic 2-bromo-1-arylethanols was achieved with high selectivity. Irrespective of the electronic nature and the substitution patterns on the aromatic rings, a variety of substrates were suitable for this reaction. The branched acyl component was considered to be optimal for obtaining high s-values. The transition state of the reaction was proposed based on the absolute configuration of the obtained product.
We fabricated a p-type nickel oxide (NiO)/gold nanoparticle (Au-NP)/n-type titanium dioxide (TiO2) structure in which Au-NPs are placed in the p-n junction of TiO2 and NiO. The photoelectric properties of NiO/Au-NPs/TiO2 suggest that the main driving force of the hole separation from Au-NPs to NiO is the local electric field of the depletion layer of the p-n junction of TiO2 and NiO rather than the Schottky junction of Au and NiO.
A method for the selective synthesis of 9-substituted fluorenols (FOLs) was developed by suppressing intermolecular cyclization and promoting intramolecular C–H functionalization. This protocol was applied to the synthesis of heteroring-fused FOLs. Further, the obtained FOLs were converted to fulvenes by dehydration.
We have recently developed a series of arsenic ligands based on practical synthetic strategies. Herein, three kinds of bidentate arsenic ligands with rigid linkers were selected to construct dinuclear rhombic copper(I) iodide (CuI) complexes, whose structures were analyzed by X-ray crystallography. They had sufficient solubility in organic solvents, and it was confirmed that their coordination forms were kept in the solutions. Intense solid-state emissions were observed even at room temperature, and the emission colors were varied from yellow to red by the ligands.
A superhydrophobic bilayer surface was created with a contact angle (CA) of 157.3 ± 1° and sliding angle (SA) of 2° ± 0.5° using a simple one-step solvothermal process. The bionic micro/nano structures are similar to the flower of a carnation and common sowthistle, which plays an important role in resisting corrosion. In addition, potentiodynamic polarization shows that the superhydrophobic bilayer surface has excellent corrosion resistance. This preparation is beneficial as it is simple to fabricate, low cost, is easily prepared across large areas, and has excellent corrosion resistance, amongst other benefits. It can effectively broaden the application of magnesium alloys and extend to other conductive metal materials.
Salt cavern redox flow batteries with a large salt-cavern storing electrolyte are a promising large-scale energy storage technology. Here a low-cost iron/organic redox material system was proposed to explore salt cavern redox flow batteries. To avoid the formation of ferric hydroxide, ligand threonine was used to enhance the stability of the ferric ion in aqueous solution. Paired with a two electron viologen catholyte and saturated brine solution as supporting electrolyte, the battery delivered a high battery efficiency and cycling stability, 99% CE, 80% EE, and an average 99.5% capacity retention per cycle. The impressive battery performance provides a promising strategy for developing large-scale salt-cavern redox flow batteries.
Density functional theory calculations with plane-wave basis sets are often used for theoretical investigations of solid materials; nevertheless, analysis techniques for open shell structures are insufficient. In this study, we established an electron density-based estimation scheme for the diradical character (y). The values estimated by the proposed and conventional schemes are consistent. Additionally, the estimated y values are qualitatively the same as the experimentally obtained values, and the values obtained using plane-wave and atom-centred basis sets are equal.