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As a system shrinks down in size, more and more molecules are found in its surface region, so surface contribution becomes a large or even a dominant part of its thermodynamic potentials. Surface tension is a venerable scientific concept; Gibbs defined it as the excess of grand potential of an inhomogeneous system with respect to its bulk value per interface area [J. W. Gibbs, “The Collected Works” in Thermodynamics (1928), Vol. 1]. The mechanical definition expresses it in terms of pressure tensor. So far, it has been believed the two definitions always give the same result. We show that the equivalence can break down for fluids confined in narrow pores. New concepts of integral and differential surface tensions, along with integral and differential adsorptions, need to be introduced for extending Gibbs thermodynamics of interfaces. We derived two generalized Gibbs adsorption equations. These concepts are indispensable for an adequate description of nanoscale systems. We also find a relation between integral surface tension and Derjaguin’s disjoining pressure. This lays down the basis for measuring integral and differential surface tensions from disjoining pressure by using an atomic force microscope.

Disjoining pressure was discovered by Derjaguin in 1930’s, which describes the difference between the pressure of a strongly confined fluid and the corresponding one in a bulk phase. It has been revealed recently that the disjoining pressure is at the origin of distinct differential and integral surface tensions for strongly confined fluids. Here we show how the twin concept, disjoining chemical potential, arises in a reminiscent way although it comes out eighty years later. This twin concept advances our understanding of nanoscale thermodynamics. Ensemble-dependence (or environment-dependence) is one hallmark of thermodynamics of small systems. We show that integral surface tension is ensemble-dependent while differential surface tension is not. Moreover, two generalized Gibbs-Duhem equations involving integral surface tensions are derived, as well as two additional adsorption equations relating surface tensions to adsorption-induced strains. All the results obtained in this work further evidence that an approach alternative of Hill’s nanothermodynamics is possible, by extending Gibbs surface thermodynamics instead of resorting to Hill’s replica trick. Moreover, we find a compression-expansion hysteresis without any underlying phase transition. Matter behaves differently at the nanoscale. Here, the author introduces the concept of a disjoining chemical potential for nanoscale thermodynamics, showing that thermodynamic functions depend on the environment, and suggests possible experimental verifications.

AbstractA novel sandwich-like heterotrinuclear [Zn(II)2Mn(III)] complex, [Zn(L)Cl2Mn]Cl, has been constructed successfully from a bicompartmental 3-MeOSalphen ligand (H2L), N,N′-bis(3-methoxy-salicylidene)phenylene-1,2-diamine. The chemically obained structure was determined through single crystal X-ray diffraction and spectrochemical (IR and UV-Vis) analyses. The structural studies revealed that characteristic inner N2O2 compartment of H2L is occupied by Zn(II) atom and outer O2O2 compartment is coordinated by Mn(III) atom in the Zn(II)–Mn(III) complex. The Zn(II)–Mn(III) complex can be used as a potential light-emitting material owing to the fluorescent property. In addition, density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations were performed to take insight of experimental electronic spectra. Interaction region indicator (IRI) analyses were calculated to show relative chemical bond changes before and after coordination.

The optical properties of the symmetric salamo-like chemical probe (H2CS) of Cu2+ were studied in EtOH/H2O (1:1, v/v) solution by UV-Vis and fluorescence spectroscopy. In the fluorescence spectrum, the coordination of Cu2+ with H2CS results in fluorescence quenching owing to the paramagnetic nature of Cu2+ ions. The binding constant of Cu2+ to the H2CS sensor was calculated as 1.17 × 1011 M–1 and LOD was obtained as 5.3 × 10–8 M. When Cu2+ ions were added, the UV-Vis spectra changed, obviously due to the electron transfer from sensor to metal bond, and a new absorption band appeared at 372 nm. When the ethylenediaminetetraacetic acid (EDTA) solution was added to the H2CS–Cu2+ solution, causing a large binding constant, with EDTA releasing the free sensor molecule and finally achieving a fluorescence shutdown phenomenon.

AbstractA new bis(salamo)-type ligand has been designed and synthesized, and its hetero-trinuclear [Cu(II)2Ca(II)] complex has been successfully prepared. It is characterized by elemental analyses, IR spectra, UV-Vis absorption spectra and X-ray single crystal diffraction. Meanwhile, Hirshfeld surfaces and fluorescence properties were investigated. The hetero-trinuclear [Cu(II)2Ca(II)] complex was obtained by 2 equiv. Cu(NO3)2·3H2O and 1 equiv. Ca(OAc)2·2H2O with 1 equiv. H4L. Obviously, there is the ligand, metal Cu(II) and Ca(II) ratio of 1:2:1 which formed the hetero-trinuclear [Cu(II)2Ca(II)] complex. X-ray diffraction result showed that Cu(II) and Ca(II) atoms in the crystal are geometric polyhedrons with different shapes. Both Cu(II) atoms are located respectively in N2O2 cavities of the completely deprotonated ligand (L)4– unit. Cu(II) and Ca(II) atoms are bridged by nitrate groups, so that the two Cu(II) (Cu1 and Cu2) atoms have slightly distorted square pyramid geometries. In addition, Ca(II) atom is located in a O6 cavity of the ligand (L)4– unit and possesses square antiprism with eight coordination.

AbstractAn unprecedented dinuclear Ni(II) complex [Ni2(L)(HL)(μ-OAc)(H2O)2]·3CH3CH2OH is successfully synthesized by the complexation of an asymmetric salamo-based ligand (H2L) and Ni(II) acetate tetrahydrate and characterized by elemental analyses, UV-Vis and IR spectra, and X-ray crystallography analyses. Surprisingly, in the asymmetric unit of the Ni(II) complex, a fully deprotonated ligand (L)2– unit and a partially deprotonated ligand (HL)– unit wrapps two Ni(II) atoms, with the μ-OAc– anion bridging two adjacent Ni(II) atoms. The two Ni(II) atoms possess different coordination environments and twisted octahedral geometries. The hexacoordinated Ni(II) atom (Ni1) is located in the N2O4 donor cavity, but another hexacoordinated Ni(II) atom (Ni2) is located in a NO5 donor coordination environment. Meanwhile, a1D chain structure is formed by two N–O⋯π interactions. Hirshfeld surfaces and fluorescent properties are investigated.

Mind wandering is often characterized by attention oriented away from an external task towards our internal, self-generated thoughts. This universal phenomenon has been linked to numerous disruptive functional outcomes, including performance errors and negative affect. Despite its prevalence and impact, studies to date have yet to identify robust behavioral signatures, making unobtrusive, yet reliable detection of mind wandering a difficult but important task for future applications. Here we examined whether electrophysiological measures can be used in machine learning models to accurately predict mind wandering states. We recorded scalp EEG from participants as they performed an auditory target detection task and self-reported whether they were on task or mind wandering. We successfully classified attention states both within (person-dependent) and across (person-independent) individuals using event-related potential (ERP) measures. Non-linear and linear machine learning models detected mind wandering above-chance within subjects: support vector machine (AUC = 0.715) and logistic regression (AUC = 0.635). Importantly, these models also generalized across subjects: support vector machine (AUC = 0.613) and logistic regression (AUC = 0.609), suggesting we can reliably predict a given individual’s attention state based on ERP patterns observed in the group. This study is the first to demonstrate that machine learning models can generalize to “never-seen-before” individuals using electrophysiological measures, highlighting their potential for real-time prediction of covert attention states.

Background. The Maraviroc versus Optimized Therapy in Viremic Antiretroviral Treatment-Experienced Patients (MOTIVATE) studies compared maraviroc versus placebo in treatment-experienced patients with CCR5-using (R5) human immunodeficiency virus type 1 (HIV-1), screened using the original Trofile assay. A subset with non-R5 HIV infection entered the A4001029 trial. We retrospectively examined the performance of a genotypic tropism assay based on deep sequencing of the HIV env V3 loop in predicting virologic response to maraviroc in these trials. Methods. V3 amplicons were prepared from 1827 screening plasma samples and sequenced on a Roche/454 GS-FLX to a depth of >3000 sequences/sample. Samples were considered non-R5 if ≥2% of their viral population scored greater than or equal to -4.75 or ≤3.5 using the PSSM x4/R5 or geno2pheno algorithms, respectively. Results. Deep sequencing identified more than twice as many maraviroc recipients as having non-R5 HIV, compared with the original Trofile. With use of genotyping, we determined that 49% of maraviroc recipients with R5 HIV at screening had a week 48 viral load <50 copies/mL versus 26% of recipients with non-R5. Corresponding percentages were 46% and 23% with screening by Trofile. In cases in which screening assays differed, median week 8 log₁₀ copies/mL viral load decrease favored 454. Other parameters predicted by genotyping included likelihood of changing to non-R5 tropism. Conclusions. This large study establishes deep V3 sequencing as a promising tool for identifying treatment-experienced individuals who could benefit from CCR5-antagonist—containing regimens.

People constantly invest effort to seek information in everyday life, even if the information is of no instrumental value for the decision at hand. However, the mechanism underlying people’s willingness to exert effort in exchange for information remains unclear. Previous work has suggested that desirability and uncertainty are two key factors influencing information-seeking, but few studies have tested if these factors are important when exerting physical effort in exchange for information. Additionally, it remains unknown whether different kinds of uncertainty, i.e., risk and ambiguity, have differential impacts. In the current study, we developed a novel information-seeking task to quantify the value of non-instrumental information using incentive-compatible physical effort to examine how effort changes as a function of desirability and uncertainty. Across two studies ( N = 123), we found that people’s willingness to exert effort is positively associated with outcome expected value under both risk and ambiguity. Additionally, people exert more effort when outcome distribution uncertainty increases in risky situations, but are insensitive to ambiguity, except when facing extreme ambiguity. Our results demonstrate an unexpected dissociation. Humans will engage in effort-based information-seeking, even for non-instrumental information, when facing risk. In contrast, they show a much lower willingness to expend effort to resolve non-instrumental ambiguity.

The emergence of the H7N9 influenza virus in humans in Eastern China has raised concerns that a new influenza pandemic could occur. Here, we used a ferret model to evaluate the infectivity and transmissibility of A/Shanghai/2/2013 (SH2), a human H7N9 virus isolate. This virus replicated in the upper and lower respiratory tracts of the ferrets and was shed at high titers for 6 to 7 days, with ferrets showing relatively mild clinical signs. SH2 was efficiently transmitted between ferrets via direct contact, but less efficiently by airborne exposure. Pigs were productively infected by SH2 and shed virus for 6 days but were unable to transmit the virus to naïve pigs or ferrets. Under appropriate conditions, human-to-human transmission of the H7N9 virus may be possible.