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Traditionally, two approaches have been employed for structural equation modeling: covariance structure analysis and partial least squares. A third alternative, generalized structured component analysis, was introduced recently in the psychometric literature. The authors conduct a simulation study to evaluate the relative performance of these three approaches in terms of parameter recovery under different experimental conditions of sample size, data distribution, and model specification. In this study, model specification is the only meaningful condition in differentiating the performance of the three approaches in parameter recovery. Specifically, when the model is correctly specified, covariance structure analysis tends to recover parameters better than the other two approaches. Conversely, when the model is misspecified, generalized structured component analysis tends to recover parameters better. Finally, partial least squares exhibits inferior performance in parameter recovery compared with the other approaches. In particular, this tendency is salient when the model involves cross-loadings. Thus, generalized structured component analysis may be a good alternative to partial least squares for structural equation modeling and is recommended over covariance structure analysis unless correct model specification is ensured.

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The high-volume synthesis of two-dimensional (2D) materials in the form of platelets is desirable for various applications. While water is considered an ideal dispersion medium, due to its abundance and low cost, the hydrophobicity of platelet surfaces has prohibited its widespread use. Here we exfoliate 2D materials directly in pure water without using any chemicals or surfactants. In order to exfoliate and disperse the materials in water, we elevate the temperature of the sonication bath, and introduce energy via the dissipation of sonic waves. Storage stability greater than one month is achieved through the maintenance of high temperatures, and through atomic and molecular level simulations, we further discover that good solubility in water is maintained due to the presence of platelet surface charges as a result of edge functionalization or intrinsic polarity. Finally, we demonstrate inkjet printing on hard and flexible substrates as a potential application of water-dispersed 2D materials.

Due to its strong correlation with the pathophysiology of many diseases, information about human red blood cells (RBCs) has a crucial function in hematology. Therefore, measuring and understanding the morphological, chemical, and mechanical properties of individual RBCs is a key to understanding the pathophysiology of a number of diseases in hematology, as well as to opening up new possibilities for diagnosing diseases in their early stages. In this study, we present the simultaneous and quantitative measurement of the morphological, chemical, and mechanical parameters of individual RBCs employing optical holographic microtomography. In addition, it is demonstrated that the correlation analyses of these RBC parameters provide unique information for distinguishing and understanding diseases.

Abstract:The objective of this study was to determine the relationship between the plucking periods and the major constituents and the antioxidant activity in green tea. Green tea was prepared from leaves plucked from the end of April 2013 to the end of May 2013 at intervals of one week or longer. The contents of theanine, theobromine, caffeine, catechin (C), and gallocatechin gallate (GCg) were significantly decreased, whereas those of epicatechin (EC), epigallocatechin gallate (EGCg) and epigallocatechin (EGC) were significantly increased along with the period of tea leaf plucking. In addition, antioxidant activity of green tea and standard catechins was investigated using ABTS, FRAP and DPPH assays. The highest antioxidant activity was observed in relatively the oldest leaf, regardless of the assay methods used. Additionally, the order of antioxidant activity of standard catechins was as follows: EGCg ≥ GCg ≥ ECg > EGC ≥ GC ≥ EC ≥ C. Moreover, the cis-catechins contents were the key factor affecting the antioxidant activity of green tea in all assays employed (ABTS, r = 0.731, p < 0.01; FRAP, r = 0.886, p < 0.01; DPPH, r = 0.778, p < 0.01).

We functionally analyzed the role of metal ions in RNA-dependent RNA synthesis by three recombinant RNA-dependent RNA polymerases (RdRps) from GB virus-B (GBV), bovine viral diarrhea virus (BVDV), and hepatitis C virus (HCV), with emphasis on the HCV RdRp. Using templates capable of both de novo initiation and primer extension and RdRps purified in the absence of metal, we found that only reactions with exogenously provided Mg 2؉ and Mn 2؉ gave rise to significant amounts of synthesis. Mg 2؉ and Mn 2؉ affected the mode of RNA synthesis by the three RdRps. Both metals supported primer-dependent and de novo-initiated RNA by the GBV RdRp, while Mn 2؉ significantly increased the amount of de novo-initiated products by the HCV and BVDV RdRps. For the HCV RdRp, Mn 2؉ reduced the K m for the initiation nucleotide, a GTP, from 103 to 3 M. However, it increased de novo initiation even at GTP concentrations that are comparable to physiological levels. We hypothesize that a change in RdRp structure occurs upon GTP binding to prevent primer extension. Analysis of deleted proteins revealed that the C terminus of the HCV RdRp plays a role in Mn 2؉ -induced de novo initiation and can contribute to the suppression of primer extension. Spectroscopy examining the intrinsic fluorescence of tyrosine and tryptophan residues in the HCV RdRp produced results consistent with the protein undergoing a conformational change in the presence of metal. These results document the fact that metal can affect de novo initiation or primer extension by flaviviral RdRps.Polymerases are metal-activated enzymes that use divalent metals for nucleotide polymerization. The paradigm for catalysis by DNA-dependent RNA polymerases is that two Mg 2ϩ ions coordinate the nucleotides and catalyze the formation of the phosphodiester bonds (11). These metals are specifically recognized by amino acids in the catalytic pocket of the polymerase.

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