Excitonic Coupled-cluster Theory: Part I, General Formalism

<div> <div>A shortcoming of presently available fragment-based methods is that electron correlation (if included) is described at the level of individual electrons, resulting in many redundant evaluations of the electronic relaxations associated with any given fluctuation. A generalized variant of coupled-cluster (CC) theory is described, wherein the degrees of freedom are fluctuations of fragments between internally correlated states. The effects of intra-fragment correlation on the inter-fragment interaction is pre-computed and permanently folded into the effective Hamiltonian. This article provides a high-level description of the CC variant, establishing some useful notation, and it demonstrates the advantage of the proposed paradigm numerically on model systems. A companion article shows that the electronic Hamiltonian of real systems may always be cast in the form demanded. This framework opens a promising path to build finely tunable systematically improvable methods to capture precise properties of systems interacting with a large number of other systems. </div> </div

Excitonic Coupled-cluster Theory: Part II, Electronic Hamiltonian

<div> <div> <div>Generic equations were presented in a companion article for a variant of coupled-cluster theory that operates directly on fragment excitation coordinates (excitonic CC), and its promise was illustrated on model systems. Three conditions were asserted for the excitonic CC framework to be valid and practicable; these concerned (1) the existence of an appropriate fragment-decomposed complete basis, (2) the existence of single-fragment fluctuation operators referencing that basis, and (3) the existence and complexity of the Hamiltonian resolved in terms of strings of those operators. In this article, we take on these assertions specificially for fragment-decomposed electronic systems, proceeding ultimately to explicit recipes for resolving the Hamiltonian in a systematically improvable manner. Though framed in the context of excitonic CC theory, the derivations here are applicable to the general inter-fragment electron-exchange problem. The number of terms in the exactly transformed Hamiltonian formally scales quartically, but this can be reduced to quadratic within an arbitrary error tolerance. The vast majority of these terms are outside of exchange range and may be decomposed efficiently in terms of single-fragment information. </div> </div> </div

Adjustable Tribological Behavior of Glucose-Sensitive Hydrogels

Stimuli-responsive hydrogels have been considered to have various applications in numerous fields. In the present work, a double-network (DN) hydrogel has been synthesized. The copolymers of 2-acrylamide-2-methylpropane sulfonic acid (AMPS) and acrylamide (AM) [P­(AMPS-<i>co</i>-AM)] are prepared as the 1st network and poly­(acrylic acid) as the 2nd network. This DN hydrogel is sensitive to glucose by introducing the glucose-sensitive group phenylboronic acid to the network. The tribological properties of this glucose-sensitive DN hydrogel have been investigated using a universal mechanical tester (UMT-5). The tribological results show that the friction coefficient varied with the glucose solution. The friction coefficient increased to a maximum of 0.06, and finally decreased to 0.025 with the increase in the glucose concentration. An adjustable friction coefficient of the hydrogel, between 0.025 and 0.056, was achieved along with the change of lubricant. According to the tribological experimental results and the analysis of the DN structure, it can be deduced that a hydrated layer exists in the interface of the hydrogel. The hydrated layers consisting of water molecules are bounded with the hydrophilic group of the hydrogel network by hydrogen bonds. The change in the number of water molecules leads to the difference in the water content of the hydrogel, which further resulted in the various tribological properties. In addition, the hydrogel’s mesh size also has an impact on the change in friction coefficient. In general, the adjustable friction of the hydrogel in a glucose environment is achieved

Spirocyclic Nortriterpenoids with NGF-Potentiating Activity from the Fruits of <i>Leonurus heterophyllus</i>

Four new spirocyclic nortriterpenoids, leonurusoleanolide A (<b>1</b>), leonurusoleanolide B (<b>2</b>), leonurusoleanolide C (<b>3</b>), and leonurusoleanolide D (<b>4</b>), were isolated from the MeOH extract of the fruits of <i>Leonurus heterophyllus.</i> Compounds <b>1</b> and <b>2</b>, and compounds <b>3</b> and <b>4</b>, were found to exist as equilibrium mixtures of <i>trans</i> and <i>cis</i> isomers. Mixtures of <b>1</b> and <b>2</b>, and <b>3</b> and <b>4</b>, significantly enhanced the neurite outgrowth of nerve growth factor-treated PC12 cells at concentrations ranging from 1 to 30 μM. Compound <b>8</b> was also found to have a neurite outgrowth-promoting effect at concentrations of 1 and 10 μM. The structure–activity relationship of these compounds is discussed

Nerve Growth Factor-Potentiating Benzofuran Derivatives from the Medicinal Fungus <i>Phellinus ribis</i>

Four new benzofuran derivatives, ribisin A (<b>1</b>), ribisin B (<b>2</b>), ribisin C (<b>3</b>), and ribisin D (<b>4</b>), were isolated from the MeOH extract of the fruiting bodies of <i>Phellinus ribis.</i> Their structures including their absolute configurations were determined by NMR and CD exciton chirality methods. Compounds <b>1</b>–<b>4</b> were found to promote neurite outgrowth in NGF-mediated PC12 cells at concentrations ranging from 1 to 30 μM. The structure–activity relationships of these compounds are also discussed

Reducing Adhesion Force by Means of Atomic Layer Deposition of ZnO Films with Nanoscale Surface Roughness

Adhesion is a big concern for the design of Si-based microelectromechanical devices. A ZnO film with nanoscale surface roughness is a promising candidate to decrease adhesion as the protective coating. In this study, the adhesion force of ZnO films prepared by atomic layer deposition (ALD) on a Si (100) substrate was studied. The root-mean-square (RMS) roughness of the ZnO films was in the range of 0.7–4.28 nm, and the contact angle of water was in the range of 85–88°. The adhesion force was measured by atomic force microscopy (AFM) at both low (12%) and high (60%) relative humidities. The results show that the adhesion force decreases as the surface roughness increases. A low adhesion force at high RMS roughness is attributed to the large asperities on the film, and a large adhesion force at high humidity is attributed to the large capillary force. The experimental adhesion force was compared to the force calculated using the Rabinovich model. Although the theoretical value underestimates the experimental value, the proportion of the two components of the adhesion force is clearly shown. At the low humidity, the van der Waals force component differs not greatly with the capillary force component, while at the high humidity, the capillary force component becomes dominant

Mitochondrial-targeted MsrA overexpression does not alter expression of mitochondrial unfolded protein response in muscle from HFD-fed mice.

<p>(A) Representative blots for indicated proteins. Complex I subunit NDUFB8 (CI-20) was used as a loading control. (B). Quantification of (A). Bars represent mean (relative to mean values in WT) ± SEM. Asterisks represent p<0.05 between genotypes by Student’s t-test.</p

Overexpression of MsrA in the mitochondria prevents obesity-induced insulin resistance without altering weight gain.

<p>(A) Body weights of WT (n = 26), TgMito MsrA (n = 19), and TgCyto MsrA (n = 12) mice fed standard rodent chow (SD) or high fat diet (HFD). Bars represent mean body weight ± SEM. (B) Body weight gain of mice in (A) with HFD feeding. (C) Glucose tolerance tests of WT (n = 22), TgMito MsrA (n = 13), and TgCyto MsrA (n = 7) maintained on standard rodent chow (SD) or high fat diet (HFD). Circles represent mean body weight ± SEM.</p

Mitochondrial MsrA overexpression prevents insulin resistance and hyperinsulinemia caused by obesity.

<p>(A) Insulin tolerance tests of WT (n = 22), TgMito MsrA (n = 13), and TgCyto MsrA (n = 7) mice maintained on standard rodent chow (SD) or high fat diet (HFD). All values for each genotype are normalized to the fasting blood glucose level of that genotype prior to injection of insulin. Asterisks represent p<0.05 by one-way ANOVA. (B) Area under curve (AUC) calculated for Insulin tolerance tests in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0139844#pone.0139844.g001" target="_blank">Fig 1</a>. Bars represent mean AUC x SEM. (C) Fasting (6 hour) plasma insulin concentration and HOMA-IR (normalized to mean WT value) of indicated mice maintained on high fat diet. (D) Relative plasma concentrations of leptin (Lep), adiponectin (Adip), and triglycerides (TAG) from overnight fasted, high fat diet-fed animals (values normalized to mean WT levels for each). Bars represent mean values ± SEM. For all, asterisks represent p<0.05 by one-way ANOVA.</p

Increased MsrA in the mitochondria prevents insulin resistance even in the absence of cytosolic MsrA.

<p>(A) Insulin tolerance tests for HFD-fed MsrA KO (n = 6), TgMito MsrA (n = 4), and TgMito MsrA X KO (n = 7) mice. Circles represent mean blood glucose ± SEM. All values for each genotype are normalized to the fasting blood glucose level of that genotype prior to injection of insulin. (B) Area under curve (AUC) calculated for data in (A). Asterisks represent p<0.05 by one-way ANOVA (C) Representative blot of phosphorylation of Akt (Ser473) and GSK-3α (Ser21) in muscle (gastrocnemius) from HFD-fed mice. (D) Quantitation of phosphorylation of Akt and GSK-3α in muscle (gastrocnemius), visceral white adipose tissue (epigonadal) and liver. Values are normalized relative to mean WT value. Asterisks represent p<0.05 between genotypes by Student’s t-test. For all, bars represent mean AUC ± SEM.</p