Applications of BiOX in the Photocatalytic Reactions

BiOX (X = Cl, Br, I) families are a kind of new type of photocatalysts, which have attracted the attention of more and more researchers. The suitable band gaps and their convenient tunability via the change of X elements enable BiOX to adapt to many photocatalytic reactions. In addition, because of their characteristics of the unique layered structure and indirect bandgap semiconductor, BiOX exhibits excellent separation efficiency of photogenerated electrons and holes. Therefore, BiOX could usually demonstrate fine activity in many photocatalytic reactions. In this review, we will present the various applications and modification strategies of BiOX in photocatalytic reactions. Finally, based on a good understanding of the above issues, we will propose the future directions and feasibilities of the reasonable design of modification strategies of BiOX to obtain better photocatalytic activity toward various photocatalytic applications.

Synthesis Routes on Electrochemical Behavior of Co-Free Layered LiNi(0.5)Mn(0.5)O(2) Cathode for Li-Ion Batteries

Co-free layered LiNi_0.5Mn_0.5O₂ has received considerable attention due to high theoretical capacity (280 mAh g^-1) and low cost comparable than LiCoO₂. The ability of nickel to be oxidized (Ni²⁺/Ni³⁺/Ni⁴⁺) acts as electrochemical active and has a low activation energy barrier, while the stability of Mn⁴⁺ provides a stable host structure. However, selection of appropriate preparation method and condition are critical to providing an ideal layered structure of LiNi_0.5Mn_0.5O₂ with good electrochemical performance. In this study, Layered LiNi_0.5Mn_0.5O₂ has been synthesized by sol-gel and solid-state routes. According to the XRD, the sol-gel method provides a pure phase, and solid-state process only minimize the secondary phases to certain limit. The Ni²⁺/Mn⁴⁺ content in the sol-gel process was higher than in the solid-state reaction, which may be due to the chemical composition homogeneity of the sol-gel samples. Regarding the electrochemical behavior, sol-gel process is better than solid-state reaction. The discharge capacity is 145 mAh/g and 91 mAh/g for the sol-gel process and solid-state reaction samples, respectively.

3D Molecular Imaging of Stratum Corneum by Mass Spectrometry Suggests Distinct Distribution of Cholesteryl Esters Compared to Other Skin Lipids

The crucial barrier properties of the stratum corneum (SC) depend critically on the design and integrity of its layered molecular structure. However, analysis methods capable of spatially resolved molecular characterization of the SC are scarce and fraught with severe limitations, e.g., regarding molecular specificity or spatial resolution. Here, we used 3D time-of-flight secondary ion mass spectrometry to characterize the spatial distribution of skin lipids in corneocyte multilayer squams obtained by tape stripping. Depth profiles of specific skin lipids display an oscillatory behavior that is consistent with successive monitoring of individual lipid and corneocyte layers of the SC structure. Whereas the most common skin lipids, i.e., ceramides, C24:0 and C26:0 fatty acids and cholesteryl sulfate, are similarly organized, a distinct 3D distribution was observed for cholesteryl oleate, suggesting a different localization of cholesteryl esters compared to the lipid matrix separating the corneocyte layers. The possibility to monitor the composition and spatial distribution of endogenous lipids as well as active drug and cosmetic substances in individual lipid and corneocyte layers has the potential to provide important contributions to the basic understanding of barrier function and penetration in the SC.

Development and In-Depth Characterization of Bacteria Repellent and Bacteria Adhesive Antibody-Coated Surfaces Using Optical Waveguide Biosensing

Bacteria repellent surfaces and antibody-based coatings for bacterial assays have shown a growing demand in the field of biosensors, and have crucial importance in the design of biomedical devices. However, in-depth investigations and comparisons of possible solutions are still missing. The optical waveguide lightmode spectroscopy (OWLS) technique offers label-free, non-invasive, in situ characterization of protein and bacterial adsorption. Moreover, it has excellent flexibility for testing various surface coatings. Here, we describe an OWLS-based method supporting the development of bacteria repellent surfaces and characterize the layer structures and affinities of different antibody-based coatings for bacterial assays. In order to test nonspecific binding blocking agents against bacteria, OWLS chips were coated with bovine serum albumin (BSA), I-block, PAcrAM-g-(PMOXA, NH₂, Si), (PAcrAM-P) and PLL-g-PEG (PP) (with different coating temperatures), and subsequent Escherichia coli adhesion was monitored. We found that the best performing blocking agents could inhibit bacterial adhesion from samples with bacteria concentrations of up to 10⁷ cells/mL. Various immobilization methods were applied to graft a wide range of selected antibodies onto the biosensor's surface. Simple physisorption, Mix&Go (AnteoBind) (MG) films, covalently immobilized protein A and avidin-biotin based surface chemistries were all fabricated and tested. The surface adsorbed mass densities of deposited antibodies were determined, and the biosensor;s kinetic data were evaluated to divine the possible orientations of the bacteria-capturing antibodies and determine the rate constants and footprints of the binding events. The development of affinity layers was supported by enzyme-linked immunosorbent assay (ELISA) measurements in order to test the bacteria binding capabilities of the antibodies. The best performance in the biosensor measurements was achieved by employing a polyclonal antibody in combination with protein A-based immobilization and PAcrAM-P blocking of nonspecific binding. Using this setting, a surface sensitivity of 70 cells/mm² was demonstrated.

Metal-Ions Intercalation Mechanism in Layered Anode From First-Principles Calculation

Layered structure (MoS2) has the potential use as an anode in metal-ions (M-ions) batteries. Here, first-principles calculations are used to systematically investigate the diffusion mechanisms and structural changes of MoS2 as anode in lithium (Li)-, sodium (Na)-, magnesium (Mg)- and Zinc (Zn)-ions batteries. Li and Na ions are shown to be stored in the MoS2 anode material due to the strong adsorption energies (~-2.25 eV), in contrast to a relatively weak adsorption of Mg and Zn ions for the pristine MoS2. To rationalize the results, we evaluate the charge transfer from the M-ions to the MoS2 anode, and find a significant hybridization between the adsorbed atoms and S atoms in the MoS2 anode. Furthermore, the migration energy barriers of M ions are explored using first-principles with the climbing image nudged elastic band (CINEB) method, and the migration energy barrier is in the order of Zn > Mg > Li > Na ions. Our results combined with the electrochemical performance experiments show that Li- and Na-ions batteries have good cycle and rate performance due to low ions migration energy barrier and high storage capability. However, the MoS2 anode shows poor electrochemical performance in Zn- and Mg-ions batteries, especially Zn-ion batteries. Further analysis reveals that the MoS2 structure undergoes the phase transformation from 2H to 1T during the intercalation of Li and Na ions, leading to strong interaction between M ions and the anode, and thus higher electrochemical performance, which, however, is difficult to occur in Mg- and Zn-ions batteries. This work focuses on the theoretical aspects of M-ions intercalation, and our findings may stimulate the experimental work for the intercalation of multi-ions to maximize the capacity of anode in M-ions batteries.

Synthesis, crystal structure and thermal properties of poly[bis-[μ2-3-(amino-meth-yl)pyridine]-bis-(thio-cyanato)-cobalt(II)]

The reaction of Co(NCS)2 with 3-(amino-meth-yl)pyridine as coligand leads to the formation of crystals of the title compound, [Co(NCS)2(C6H8N2)2] n , that were characterized by single-crystal X-ray analysis. In the crystal structure, the CoII cations are octa-hedrally coordinated by two terminal N-bonded thio-cyanate anions as well as two pyridine and two amino N atoms of four symmetry-equivalent 3-(amino-meth-yl)pyridine coligands with all pairs of equivalent atoms in a trans position. The CoII cations are linked by the 3-(amino-meth-yl)pyridine coligands into layers parallel to the ac plane. These layers are further linked by inter-molecular N-H⋯S hydrogen bonding into a three-dimensional network. The purity of the title compound was determined by X-ray powder diffraction and its thermal behavior was investigated by differential scanning calorimetry and thermogravimetry.

Surface Adsorption Properties and Layer Structures of Homogeneous Polyoxyethylene-Type Nonionic Surfactants in Quaternary-Ammonium-Salt-Type Amphiphilic Gemini Ionic Liquids with Oxygen- or Nitrogen-Containing Spacers

The amphiphilic ionic liquids containing an alkyl chain in molecules form nano-structure in the bulk, although they also show surface activity and form aggregates in aqueous solutions. Although insights into the layer structures of ionic liquids were obtained using X-ray and neutron scattering techniques, the nanostructures of ionic liquids remain unclear. Herein, the surface adsorption and bulk properties of homogeneous polyoxyethylene (EO)-type nonionic surfactants (C_xEO₆; x = 8, 12, or 16) were elucidated in quaternary-ammonium-salt-type amphiphilic gemini ionic liquids with oxygen or nitrogen-containing spacers [2C_n(Spacer) NTf₂; (Spacer) = (2-O-2), (2-O-2-O-2), (2-N-2), (2/2-N-2), (3), (5), or (6); n = 10, 12, or 14 for (2-O-2) and n = 12 for all other spacers] by surface tension, small- and wide-angle X-ray scattering, cryogenic transmission electron microscopy, and viscosity measurements. The surface tension of C₁₂EO₆ in 2C_n(Spacer) NTf₂ with oxygen-containing spacers increased with increasing concentration of C₁₂EO₆, becoming close to that of C₁₂EO₆ alone, indicating that the amphiphilic ionic liquid adsorbed at the interface was replaced with C_xEO₆. In contrast, both 2C_n(Spacer) NTf₂ with nitrogen-containing spacers and nonionic surfactants remained adsorbed at the interface at high concentrations. In the bulk, it was found that 2C_n(Spacer) NTf₂ formed layer structures, in which the spacing depended on the alkyl chain length of C_xEO₆. These insights are expected to advance the practical applications of amphiphilic ionic liquids such as ion permeation, drug solubilization, and energy delivery systems.

Two monosodium salt hydrates of Colour Index Pigment Red 48

We report herein the crystal structures of a monohydrate of Colour Index Pigment Red 48 (P.R.48) (systematic name: monosodium 2-{2-[3-carboxy-2-oxo-1,2-dihydronaphthalen-1-ylidene]hydrazin-1-yl}-4-chloro-5-methylbenzenesulfonate monohydrate), Na⁺·C₁₈H₁₂ClO₆S^-·H₂O, and a dihydrate, Na⁺·C₁₈H₁₂ClO₆S^-·2H₂O. The two monosodium salt hydrates of P.R.48 were obtained from in-house synthesized P.R.48. Both have monoclinic (P2₁/c) symmetry at 173 K. The crystal packing of both crystal structures shows a layer arrangement whereby N-H...O and O-H...O hydrogen bonds are formed.

P2-Na2/3MnO2 by Co Incorporation: As a Cathode Material of High Capacity and Long Cycle Life for Sodium-Ion Batteries

The P2-Na_2/3MnO₂ compound is one of the attractive cathodes for sodium-ion batteries due to its high initial capacity and abundance of Na and Mn elements in nature. The existence of Mn³⁺ Jahn-Teller ion, however, impedes electrode performance for long term. Here, we challenge to minimize the effect of the Jahn-Teller distortion caused by Mn³⁺ in the structure, via substitution of Mn³⁺ by Co³⁺ in P2-Na_2/3[Mn_1-xCo_x]O₂ (x = 0-0.3). The P2-Na_2/3[Mn_0.8Co_0.2]O₂ compound substantializes the electrochemical performance with a capacity of about 175 mAh g^-1 (26 mA g^-1) and retained over 90% of its initial capacity for 300 cycles at 0.1 C (26 mA g^-1) and 10 C (2.6 A g^-1). The operando X-ray diffraction study indicates that a single-phase reaction is associated with the insertion of sodium ions into the structure, accompanied by a small volume change of approximately 3%. Furthermore, ex situ X-ray diffraction and high-resolution transmission electron microscopy results show that the crystal structure remained after 300 continuous cycles. It is believed that such good electrode performances attribute to the structural stabilization assisted by the presence of Co³⁺ in the crystal structure. Our finding provides a way to take advantage of low-cost Mn-rich cathode materials for sodium-ion batteries.

The localization of rice prolamin species in protein body type I is determined by the temporal control of gene expression of the respective prolamin promoters

Rice prolamin species form a layered structure in the protein body type I (PB-I) storage organelle. Rice prolamins are classified as 10 kDa, 13a-1, 13a-2, 13b-1, 13b-2 and 16 kDa prolamin. Prolamin species form layer structure in PB-I in order of 10 kDa core, 13b-1 layer, 13a (13a-1 and 13a-2) and 16 kDa middle layer and 13b-2 outer-most layer. In a previous study, we showed that the fusion proteins in 13b-2 prolamin-GFP, 13a-1 prolamin-GFP and 10 kDa prolamin-GFP were localized in the same layer of PB-I as the native prolamin, when they were expressed by their respective native prolamin promoters. Our preliminary study suggested that the temporal control of the native prolamin promoters was responsible for the localization of the respective prolamins. The aim of this study was to determine whether the use of a prolamin promoter other than the native prolamin promoter would change the localization of prolamin-GFP fusion proteins. For this purpose, we generated transgenic lines expressing 13b-2 prolamin-GFP and 13a-1 prolamin-GFP fusion proteins driven by each prolamin promoter other than the native prolamin promoter. As a result, the localization of the fusion protein in PB-I was changed. Based on our results, foreign protein localization in PB-I can be achieved by the temporal control of the different prolamin promoters.

Interfacial Kinetics and Ionic Diffusivity of the Electrodeposited MoS2 Film

The transition-metal disulfide (MoS₂) is a fantastic material used in diverse fields of applications. Ionic diffusivity and interfacial exchange current density are model parameters that play a crucial role for the optimization of device performances, which are not clearly known for this material. The additive-free dense film of MoS₂ has been deposited by a facile electrodeposition approach and characterized by structural, morphological, and compositional analyses. This report provides the characterization of interfacial charge-transfer kinetics and diffusion of lithium ion in the MoS₂ films as a function of lithium concentration at 25 °C temperature. The interfacial exchange current density is observed to be varied barely, ∼0.069-0.066 mA/cm², with the change of lithium content, from x = 0.01-0.25, in Li _xMoS₂. The ionic diffusivity of the film is found to be in the range of ∼3 × 10^-11-10^-11 cm² s^-1 and does not vary much with the measured lithium concentration window. The electrochemical performances of the material are limited by the transport of lithium ion and interfacial kinetics over the measured state of lithium content. A submicron-size particle with high surface area is needed to be used as an electrode of the material for practical C-rates.

Scanning electron microscope studies of human metaphase chromosomes

Scanning electron microscopy (SEM) is used to evaluate potential chromosome preparations and staining methods for application in high-resolution three-dimensional X-ray imaging. Our starting point is optical fluorescence microscopy, the standard method for chromosomes, which only gives structural detail at the 200 nm scale. In principle, with suitable sample preparation protocols, including contrast enhancing staining, the surface structure of the chromosomes can be viewed at the 1 nm level by SEM. Here, we evaluate a heavy metal nucleic-acid-specific stain, which gives strong contrast in the backscattered electron signal. This study uses SEM to examine chromosomes prepared in different ways to establish a sample preparation protocol for X-rays. Secondary electron and backscattered electron signals are compared to evaluate the effectiveness of platinum-based stains used to enhance the contrast.

Methylthioureas and their morpholine and dioxane adducts; hydrogen-bonding patterns

We have redetermined the known structures of (i) methylthiourea (MTU) and (ii) 1,1-dimethylthiourea (1,1-DMTU), and investigated the structure of 1,3-dimethylthiourea (1,3-DMTU), which was however severely disordered. We report the structures of crystalline adducts of (iii) MTU with morpholine (1:1), (iv) 1,1-DMTU with 1,4-dioxane (2:1) and (v) 1,3-DMTU with 1,4-dioxane (2:1). Finally, (vi) we determined the structure of tetramethylthiourea (TetMTU). (i) In both independent molecules of MTU, the methyl group is trans to the C=S group across the C-N bond. The two molecules are connected to form an R2(2)(8) dimer by mutual N-H...S=C interactions. The packing involves six N-H...S=C interactions and is three-dimensional. (ii) The packing of the MTU-morpholine adduct is a layer structure, within which both molecules form linear aggregates parallel to the b axis. (iii) The packing of 1,1-DMTU involves N-H...S=C hydrogen bonds forming a corrugated layer structure. (iv) In the 2:1 adduct between 1,1-DMTU and 1,4-dioxane, the DMTU molecule occupies a general position whereas the dioxane molecule lies across an inversion centre. The crystal packing involves chains of alternating 1,1-DMTU R2(2)(8) dimers and dioxanes, both across inversion centres. (v) In the 2:1 adduct between 1,3-DMTU and dioxane, the 1,3-DMTU molecule occupies a general position, while the dioxane molecule lies across an inversion centre. One methyl group of the DMTU is trans and one cis to the sulfur across the corresponding C-N bond. The molecules form chains of alternating 1,3-DMTU R2(2)(8) dimers and dioxanes, both across inversion centres. Crystals of the 2:1 adduct between 1,3-DMTU and morpholine were also obtained, and were isotypic with the dioxane adduct. The morpholine molecule is disordered across the inversion centre. (vi) The molecule of TetMTU displays crystallographic twofold symmetry. Significant distortions reflect the steric pressure between methyl groups trans to sulfur. The packing of TetMTU involves only a weak hydrogen bond, C-Hmethyl...S, which connects the molecules to form layers.