MoS2 Nanosheets Supported on 3D Graphene Aerogel as a Highly Efficient Catalyst for Hydrogen Evolution

The development of efficient catalysts for electrochemical hydrogen evolution is essential for energy conversion technologies. Molybdenum disulfide (MoS₂) has emerged as a promising electrocatalyst for hydrogen evolution reaction, and its performance greatly depends on its exposed edge sites and conductivity. Layered MoS₂ nanosheets supported on a 3D graphene aerogel network (GA‐MoS₂) exhibit significant catalytic activity in hydrogen evolution. The GA‐MoS₂ composite displays a unique 3D architecture with large active surface areas, leading to high catalytic performance with low overpotential, high current density, and good stability.     

Aggregation of ranked votes considering different relative gaps between rank positions

This paper considers ranked voting systems to determine the rank order of candidates who compete for a limited number of positions. We show that the preferential voting problems based on the data envelopment analysis (DEA) (Wang et al, 2007) can be solved using the extreme points of constraints on rank position importance incorporated in the formulation. This is basically due to the fact that the so-called inverse positive property of the constraints makes it possible to easily find their extreme points. Further, we emphasize that this finding is not restricted to Wang et al’s two linear models, but is also applicable to other DEA-based preferential voting problems, which include the constraints accounting for different relative gaps between rank positions.     

Large amplitude oscillatory shear behavior of PEO-PPO-PEO triblock copolymer solutions

Rheological properties of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblock copolymer solution in both linear and nonlinear regions have been investigated. PEO-PPO-PEO triblock copolymer solution shows a dramatic change in mechanical properties as temperature changes. PEO-PPO-PEO triblock copolymer undergoes a transition from sol to gel with increase of temperature. During this transition the copolymer solution passes through three different stages, namely sol, soft gel, and hard gel. In our previous research (Hyun et al. in J Non-Newtonian Fluid Mech 55:51–65, 2002), large amplitude oscillatory shear (LAOS) behavior was found to be very sensitive to the generated microstructures. In this study, we investigated the relationship between the LAOS type and the microdomain structure. Newtonian behavior is observed in sol region, while there appear two kinds of LAOS types in the soft gel region. One is type I (G′, G′′ decreasing) and the other is a combination of type I and type IV (G′, G′′ increasing followed by decreasing). Type III (G′ decreasing, G′′ increasing followed by decreasing) is observed in the hard gel region. We compared the shape of stress curves, Lissajous pattern, and Fourier transform (FT) rheology of hard gel and soft gel under LAOS, and tried to relate the complex LAOS behavior with the microstructural change. From these investigations, it was found that the LAOS behavior and the stress pattern at large strain are closely related to the microdomain structure of PEO-PPO-PEO triblock copolymer, and provide a lot of useful information on the microstructures induced by large deformation.     

Chlorin e6 Derivative Radachlorin Mainly Accumulates in Mitochondria,Lysosome and Endoplasmic Reticulum and Shows High Affinity toward Tumors in Nude Mice in Photodynamic Therapy

The efficacy of photodynamic therapy (PDT) depends upon the amount of photosensitizer accumulated in the malignant tissues. Radachlorin is a popular photosensitizer used in photodynamic therapy to treat various types of cancer. In this study, we have studied the main organelles responsible for the accumulation of radachlorin in human anaplastic thyroid cancer in vitro and in vivo. The optimal time window for uptake and clearance of radachlorin also was studied. Confocal microscopic images confirmed that the radachlorin is mainly acquired by mitochondria and partially by lysosome and endoplasmic reticulum. Studies also showed that the maximum amount of radachlorin was accumulated within 3–6 h after the treatment. Radachlorin also showed a higher affinity toward malignant tumors compared to the other organs in mice xenograft model. Uptake of radachlorin reached an optimum amount within 6 h and most of the radachlorins were also cleared from the body in next 48 h. Therefore, detailed information regarding exact accumulation sites and a time window in which maximum amount of drug is accumulated and cleared were obtained by this study. Hence, not only the efficacy of the treatment can be increased but the phototoxicity after the treatment also can be controlled.     

Polyatomic anion versus acetonitrile in coordinating ability: structural properties of AgX-bearing 1,4-bis(2-isonicotinoyloxyethyl)piperazine (X??=?NO3?, CF3SO3?, ClO4?, BF4?, and PF6?)

Type studies on competitive polyatomic anion versus acetonitrile coordination in the self-assembly of a series of [Ag₂(X) _m (bip)(NCCH₃) _n ](X)_2−m (X⁻ = NO₃ ⁻, CF₃SO₃ ⁻, ClO₄ ⁻, BF₄ ⁻, and PF₆ ⁻; m = 0, 2; n = 0, 2, 4; bip = 1,4-bis(2-isonicotinoyloxyethyl)piperazine) were carried out. Each bip spacer acts as an N₄ tetradentate ligand and is linked to four silver(I) centers through two pyridine and two piperazine moieties, producing a double strand consisting of two 20-membered ring units. The coordinating environment around the silver(I) center is subtly determined by the competition of the polyatomic anions with acetonitrile, that is, by the Ag···NCCH₃ versus Ag···X interactions. The coordinating ability of acetonitrile is inversely proportional to the order of the coordination ability of the Hoffmeister series of polyatomic anions, NO₃ ⁻ ≫ CF₃SO₃ ⁻ > ClO₄ ⁻ > BF₄ ⁻ ≫ PF₆ ⁻.     

Quantitation of surface-bound proteins on biochips using MALDI-TOF MS

We report on a novel method for the quantitation of proteins specifically bound on a ligand-presenting biochip by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS). The bound protein was digested by trypsin, and the resulting peptide fragments were analyzed by MALDI-TOF MS in the presence of an isotope-labeled internal standard (IS). The IS has the same sequence as a reference peptide (RP) of the target protein digest, but a different molecular weight. The absolute amount of the specifically bound protein on a biochip is then quantitated by comparison of mass intensities between the RP and the IS. Because they have the same molecular milieu, the mass intensities of these two analytes represent the real amounts of analytes on the chip. As a model system, we tested glutathione s-transferase (GST) and a GST-fusion protein, which were captured on glutathione-presenting biochips. We observed that the glutathione densities on biochips showed a good correlation with the absolute quantity of the proteins. We believe that our method will provide an alternative to currently existing tools for the absolute quantitation of surface-bound proteins.     

Interlaboratory comparison for the determination of pesticide residues in Chinese cabbage

The results of and findings from an interlaboratory comparison among laboratories carrying out food testing of pesticide residues in the APEC (Asia–Pacific Economic Cooperation) region are presented and discussed to show critical roles of chemical metrology infrastructure in establishing traceability of measurements and in supporting existing measurement capability in safety and quality of food trade. The study material, which was prepared and certified by Korea Research Institute of Standards and Science (KRISS), was freeze-dried Chinese cabbage powder fortified with two organophosphorous pesticides (diazinon and chlorpyrifos). Among 14 participants, 12 laboratories were accredited based on ISO/IEC17025 and one laboratory was under assessment for the accreditation at the time of this study. Though all participants demonstrated very good intra-day repeatability and inter-day intermediate precision, many of them showed a large bias from the certified values. It is suggested that in addition to the accreditation system, economies are encouraged to develop appropriate chemical metrology infrastructure, which could effectively support laboratories to assure measurement traceability to SI, for which NMIs could play significant roles through their metrological services recognized in Mutual Recognition Arrangement (MRA) of the International Committee for Weights and Measures (Comité International des Poids et Mesures, CIPM).     

Transfer, amplification, and inversion of helical chirality mediated by concerted interactions of C3-supramolecular dendrimers

The synthesis, structural, and retrostructural analysis of two libraries containing 16 first and second generation C(3)-symmetric self-assembling dendrimers based on dendrons connected at their apex via trisesters and trisamides of 1,3,5-benzenetricarboxylic acid is reported. A combination of X-ray diffraction and CD/UV analysis methods demonstrated that their C(3)-symmetry modulates different degrees of packing on the periphery of supramolecular structures that are responsible for the formation of chiral helical supramolecular columns and spheres self-organizable in a diversity of three-dimensional (3D) columnar, tetragonal, and cubic lattices. Two of these periodic arrays, a 3D columnar hexagonal superlattice and a 3D columnar simple orthorhombic chiral lattice with P222(1) symmetry, are unprecedented for supramolecular dendrimers. A thermal-reversible inversion of chirality was discovered in helical supramolecular columns. This inversion is induced, on heating, by the change in symmetry from a 3D columnar simple orthorhombic chiral lattice to a 3D columnar hexagonal array and, on cooling, by the change in symmetry from a 2D hexagonal to a 2D centered rectangular lattice, both exhibiting intracolumnar order. A first-order transition from coupled columns with long helical pitch, to weakly or uncorrelated columns with short helical pitch that generates a molecular rotator, was also discovered. The torsion angles of the molecular rotator are proportional to the change in temperature, and this effect is amplified in the case of the C(3)-symmetric trisamide supramolecular dendrimers forming H-bonds along their column. The structural changes reported here can be used to design complex functions based on helical supramolecular dendrimers with different degree of packing on their periphery.     

Guiding, distribution, and storage of trains of shape-dependent droplets

We present a simple method of guiding, distributing, and storing of a train of shape-dependent droplets by using side flows, cavity guiding tracks, and storage chambers. The squeezing flow makes a train of flattened droplets to align to one side of the wall and the pushing flow guides it to one of the designated guiding tracks. Then the guided droplets move along the guiding track due to the lowered surface energy when they flow along the track. In addition, simultaneous droplet guiding and storing process has been demonstrated. An array of storage chambers placed in each track could store each train containing differently concentrated droplets. The proposed method will be useful for distribution of droplets for further processes or storing for multiplex, large-scale, dynamic assays over time.     

CMOS image sensor for detection of interferon gamma protein interaction as a point-of-care approach

Complementary metal oxide semiconductor (CMOS)-based image sensors have received increased attention owing to the possibility of incorporating them into portable diagnostic devices. The present research examined the efficiency and sensitivity of a CMOS image sensor for the detection of antigen–antibody interactions involving interferon gamma protein without the aid of expensive instruments. The highest detection sensitivity of about 1 fg/ml primary antibody was achieved simply by a transmission mechanism. When photons are prevented from hitting the sensor surface, a reduction in digital output occurs in which the number of photons hitting the sensor surface is approximately proportional to the digital number. Nanoscale variation in substrate thickness after protein binding can be detected with high sensitivity by the CMOS image sensor. Therefore, this technique can be easily applied to smartphones or any clinical diagnostic devices for the detection of several biological entities, with high impact on the development of point-of-care applications.