Photophysical Properties of Silver Clusters in Faujasite Zeolites: Does the Crystal Size Matter?

Electrostatic interactions between the zeolite cavity and confined noble-metal nanoparticles govern the photophysical properties of these materials. A better understanding of these interactions can afford new perspectives in optoelectronics applications. We investigated this interplay by revealing the peculiar photophysical properties of Ag clusters embedded in nanosized faujasite zeolite structures.

iNSP-GCAAP: Identifying nonclassical secreted proteins using global composition of amino acid properties.

Nonclassical secreted proteins (NSPs) refer to a group of proteins released into the extracellular environment under the facilitation of different biological transporting pathways apart from the Sec/Tat system. As experimental determination of NSPs is often costly and requires skilled handling techniques, computational approaches are necessary. In this study, we introduce iNSP-GCAAP, a computational prediction framework, to identify NSPs.

Comparison of Perceptions About Patient Safety Culture Between Physicians and Nurses in Public Hospitals in Vietnam.

Introduction: Patient safety culture (PSC) is a vital component in ensuring high-quality and safe patient care. Assessment of physicians' and nurses' perceptions of existing hospital PSC is the first step to promoting PSC. This paper is aimed to assess physicians' and nurses' perceptions of PSC in 5 public general hospitals in Hanoi, Vietnam.

Formation of the quasi-planar B boron cluster: topological path from B and disk aromaticity.

Formation and stability of the B boron cluster were investigated using a topological approach and the disk aromaticity model. An extensive global energy minimum search for the B system which was carried out by means of the Mexican Enhanced Genetic Algorithm (MEGA) in conjunction with density functional theory computations, confirms a quasi-planar structure as its energetically most stable isomer. Such a structural motif is derived by applying a topological leapfrog operation to a B form.

Unexpected structures of the Au gold cluster: the stars are shining.

The Au gold cluster was experimentally produced in the gas phase and characterized by its vibrational spectrum recorded using far-IR multiple photon dissociation (FIR-MPD) of AuKr. DFT and coupled-cluster theory PNO-LCCSD(T)-F12 computations reveal that, at odds with most previous reports, Au prefers two star-like forms derived from a pentaprism added by two extra Au atoms on both top and bottom surfaces of the pentaprism, along with five other Au atoms each attached on a lateral face. A good agreement between calculated and FIR-MPD spectra indicates a predominant presence of these star-like isomers.

An octacoordinated Nb atom in the NbAlH cluster.

The NbAlH cluster was formed in a molecular beam and characterized by mass spectrometry and infrared spectroscopy. Density functional theory calculations show the lowest-energy isomer is a high symmetry singlet with the Nb atom placed at the center of a distorted hexagonal Al ring and coordinated by two AlH moieties, therefore exhibiting octacoordination. The unprecedented high-symmetric geometry is attributed to the 20 valence electrons; the central Nb atom adheres to the 18-electron rule and two additional delocalized electrons stabilize the hexagonal ring.

A remarkable mixture of germanium with phosphorus and arsenic atoms making stable pentagonal hetero-prisms [M@GeE], E = P, As and M = Fe, Ru, Os.

A pentagonal hetero-prismatic structural motif was found for singly transition metal doped M@GeE clusters, where the transition metal atom is located at the centre of a (5/5) GeE prism in which Ge is mixed with either P or As atoms. Structural characterization indicates that each (5/5) GeE prism is established by joining of two GeE and GeE strings in a prismatic fashion rather than two Ge and E strings. Each string results from a remarkable mixture of Ge and E atoms and contains only one E-E connection due to the fact that Ge-E bonds are much stronger than E-E connections.

Exenatide once weekly slows gastric emptying of solids and liquids in healthy, overweight people at steady-state concentrations.

Aims: To evaluate the effects of 8 weeks' administration of exenatide (EXE) once weekly on gastric emptying of solids and liquids (using the "gold standard" technique, scintigraphy), glucose absorption and postprandial glycaemia in healthy people.

Material And Methods: A total of 32 healthy participants were randomized to receive either EXE once weekly (2 mg/wk subcutaneously; six men, 10 women, mean age 59.9 ± 0.

Transformation between Hexagonal Prism and Antiprism of the Singly and Doubly Cr-Doped Ge Clusters.

Structural transformation is a unique characteristic of atomic clusters, but it turns out very different from cluster to cluster. This theoretical study proves that the isomeric transformation between hexagonal prism and hexagonal antiprism is found for the doubly doped CrGe cluster but not for singly doped CrGe cluster. We confirm that the ground state of CrGe is the distorted hexagonal prism at the B triplet state instead of various shapes predicted in the previous studies.

Effects of single and double nickel doping on boron clusters: stabilization of tubular structures in BNi, n = 2-22, m = 1, 2.

A systematic investigation on structure, relative stabilities, dissociation behavior and bonding of the singly and doubly Ni doped boron clusters BnNim with n = 2-22 and m = 1-2, was carried out using density functional theory (TPSSh functional) calculations. Calculated results indicate that for n < 14, BnNim structures are generally formed by capping Ni atom(s) on the edge or the surface of the pure boron Bn frameworks. From n = 14, the Ni dopants exert stronger effects in such a way that the most stable isomers BnNim adopt the shape of the related double ring tubular boron structures.

Formation of the quasi-planar B boron cluster: topological path from B and disk aromaticity.

The lowest-lying isomer of the B50 boron cluster is confirmed to have a quasi-planar shape with two hexagonal holes. By applying a topological (leap-frog) dual operation followed by boron capping, we demonstrated that such a quasi-planar structure actually comes from the smallest elongated B102-, and its high thermodynamic stability is due to its inherent disk aromaticity arising from its 32 valent π electrons that fully occupy a disk configuration of [(1σ)2(1π)4(1δ)4(2σ)2(1φ)4(2π)4(1γ)4(2δ)4(1η)4]. The aromatic character of the quasi-planar B50 is further supported by a strong diatropic magnetic current flow.

Effects of lixisenatide on postprandial blood pressure, gastric emptying and glycaemia in healthy people and people with type 2 diabetes.

Aim: To evaluate the effects of the prandial glucagon-like peptide-1 receptor agonist lixisenatide on gastric emptying and blood pressure (BP) and superior mesenteric artery (SMA) blood flow, and the glycaemic responses to a 75-g oral glucose load in healthy people and those with type 2 diabetes (T2DM).

Materials And Methods: Fifteen healthy participants (nine men, six women; mean ± SEM age 67.2 ± 2.

Formation of a bi-rhodium boron tube RhB and its great CO capture ability.

The geometries, bonding and abilities for CO capture of the doubly rhodium-doped boron cluster RhB are presented. DFT calculations using the TPSSh functional show that the doubly doped RhB is stable in a high symmetry shape (D) in which two Rh dopants are vertically and oppositely coordinated to nonagonal faces of a (2 × 9) double ring B tube, having the form of a teetotum toy. Bonding of the tube is analysed using different schemes for partition of total electron density (EDI_D, AIM).

Effects of intraduodenal administration of the artificial sweetener sucralose on blood pressure and superior mesenteric artery blood flow in healthy older subjects.

Background: Postprandial hypotension (PPH) occurs frequently, particularly in older people and those with type 2 diabetes, and is associated with increased morbidity and mortality. The magnitude of the decrease in blood pressure (BP) induced by carbohydrate, fat, and protein appears to be comparable and results from the interaction of macronutrients with the small intestine, including an observed stimulation of mesenteric blood flow. It is not known whether artificial sweeteners, such as sucralose, which are widely used, affect BP.

B@Si: strong stabilizing effects of a triatomic cyclic boron unit on tubular silicon clusters.

Remarkably strong effects of the aromatic B cycle in stabilizing tubular silicon clusters were observed for the first time. The doped cluster B@Si presents a novel structural motif for silicon clusters in which a B cycle is encapsulated into a (6 × 2) Si prism giving rise to a high symmetry stable tubular structure (D). A large amount of electron density is transferred to the boron cycle, and the B unit not only retains a delocalized bonding pattern within the Si prism but also enables a two-fold aromaticity for the resulting silicon double ring.

Aromaticity of Some Metal Clusters: A Different View from Magnetic Ring Current.

The aromatic character of some small planar metallic clusters was revisited with an emphasis on their σ electrons. In contrast to previous reports, our approach based on magnetic ring current as an indicator for aromaticity points out that the σ electron delocalization in molecules behaves as an important contributor to their thermodynamic stability. Ring current maps were constructed using electron densities obtained from density functional theory calculations with the B3LYP functional and the 6-311G(d) basis set.

AuM (M=Cr, Mn, and Fe) as magnetic copies of the golden pyramid.

An investigation on structure, stability, and magnetic properties of singly doped AuM (M=Cr, Mn, and Fe) clusters is carried out by means of density functional theory calculations. The studied clusters prefer forming magnetic versions of the unique tetrahedral Au. Stable sextet AuCr is identified as the least reactive species and can be qualified as a magnetic superatom.

Theoretical Investigation of Metallic Heterofullerenes of Silicon and Germanium Mixed with Phosphorus and Arsenic Atoms M-A8E6, A = Si, Ge; E = P, As; and M = Cr, Mo, W.

Recently, metallic heterofullerenes were experimentally prepared from mixed Ge-As clusters and heavier elements of groups 14 and 15. We found that the shape of these heterofullerenes doped by transition metals appears to be a general structural motif for both silicon and germanium clusters when mixing with phosphorus and arsenic atoms. Structural identifications for MSiP, MSiAs, MGeP, and MGeAs clusters, with M being a transition metal of group 6 (Cr, Mo and W), showed that most MAE clusters, except for Cr-doped derivatives CrSiAs CrGeP, and CrGeAs, exhibit a high-symmetry fullerene shape in which metal dopant is centered in a D AE heterocage consisting of six AE pentagonal faces and three AE rhombus faces.

4d and 5d bimetal doped tubular silicon clusters SiM with M = Nb, Ta, Mo and W: a bimetallic configuration model.

Geometries and electronic properties related to the ground state stabilities of several SiM clusters (M: second-row (Nb and Mo) and third-row (Ta and W) transition metals, and their mixed bimetallic clusters M: NbMo and TaW) were explored using density functional theory (DFT) computations. The computed results show that two different structural motifs emerge as the global energy minima of such clusters. They are basically singlet tubular structures in either a C prism (A) or a C antiprism (A) form.

Theoretical Study of Small Scandium-Doped Silver Clusters ScAg with n = 1-7: σ-Aromatic Feature.

Geometry, chemical bonding, and aromatic feature of a series of small silver clusters doped by an Sc atom (ScAg with n = 1-7) were investigated by means of density functional theory calculations. A planar shape is found for ScAg including n from 4 to 7. The growth mechanism is established for the formation of the hexagonal and heptagonal metallic cycles following increase of the number of Ag atoms.

A Systematic Investigation on CrCun Clusters with n = 9-16: Noble Gas and Tunable Magnetic Property.

A systematic investigation on structure, dissociation behavior, chemical bonding, and magnetic property of Cr-doped Cun clusters (n = 9-16) is carried out using the mean of density functional theory calculations. It is found that CrCu12 is a crucial size, preferring an icosahedral Cu12 cage with the central Cr dopant. Smaller cluster sizes appear as on the way to form the CrCu12 icosahedron while larger ones are produced by attaching additional Cu atoms to the CrCu12 core.

Aromatic character of planar boron-based clusters revisited by ring current calculations.

The planarity of small boron-based clusters is the result of an interplay between geometry, electron delocalization, covalent bonding and stability. These compounds contain two different bonding patterns involving both σ and π delocalized bonds, and up to now, their aromaticity has been assigned mainly using the classical (4N + 2) electron count for both types of electrons. In the present study, we reexplored the aromatic feature of different types of planar boron-based clusters making use of the ring current approach.

Mn2@Si15: the smallest triple ring tubular silicon cluster.

The smallest triple ring tubular silicon cluster Mn2@Si15 is reported for the first time. Theoretical structural identification shows that the Mn2@Si15 tubular structure whose triple ring is composed by three five-membered Si rings in anti-prism motif, is stable in high symmetry (D5h) and singlet ground state ((1)A1'). The dimer Mn2 is placed inside the tubular along the C5 axis, and the Mn dopant form single Si-Mn bonds with Si skeleton, whereas the Mn-Mn is characterized as a triple bond.

Effects of bimetallic doping on small cyclic and tubular boron clusters: B7M2 and B14M2 structures with M = Fe, Co.

Using density functional theory with the TPSSh functional and the 6-311+G(d) basis set, we extensively searched for the global minima of two metallic atoms doped boron clusters B6M2, B7M2, B12M2 and B14M2 with transition metal element M being Co and Fe. Structural identifications reveal that B7Co2, B7Fe2 and B7CoFe clusters have global minima in a B-cyclic motif, in which a perfectly planar B7 is coordinated with two metallic atoms placed along the C7 axis. The B6 cluster is too small to form a cycle with the presence of two metals.