Nanoparticles with cubic symmetry: classification of polyhedral shapes.

Structural studies of polyhedral bodies can help to analyze geometric details of observed crystalline nanoparticles (NP) where we consider compact polyhedra of cubic point symmetry as simple models. Their surfaces are described by facets with normal vectors along selected Cartesian directions () together with their symmetry equivalents forming a direction family {}. Here we focus on polyhedra with facets of families {100}, {110}, and {111}, suggested for metal and oxide NPs with cubic lattices.

Fragment motion in motor molecules: basic concepts and application to intra-molecular rotations.

The complex motion of atoms inside large molecules can be analyzed by considering translation, rotation, and flexibility of corresponding molecular fragments and by applying classical mechanics based on Pulay forces on the atoms, as in molecular dynamics. We propose a fragment motion analysis that provides a basic qualitative understanding of the motion of the different molecular components. Further, it can help to describe or design simplified fragment motions, e.

Interlocking Molecular Gear Chains Built on Surfaces.

Periodic chains of molecular gears in which molecules couple with each other and rotate on surfaces have been previously explored by us theoretically using ab initio simulation tools. On the basis of the knowledge and experience gained about the interactions between neighboring molecular gears, we here explore the transmission of rotational motion and energy over larger distances, namely, through a longer chain of gear-like passive "slave" molecules. Such microscopic gears exhibit quite different behaviors compared to rigid cogwheels in the macroscopic world due to their structural flexibility affecting intermolecular interaction.

Interlocking Mechanism between Molecular Gears Attached to Surfaces.

While molecular machines play an increasingly significant role in nanoscience research and applications, there remains a shortage of investigations and understanding of the molecular gear (cogwheel), which is an indispensable and fundamental component to drive a larger correlated molecular machine system. Employing ab initio calculations, we investigate model systems consisting of molecules adsorbed on metal or graphene surfaces, ranging from very simple triple-arm gears such as PF and NH to larger multiarm gears based on carbon rings. We explore in detail the transmission of slow rotational motion from one gear to the next by these relatively simple molecules, so as to isolate and reveal the mechanisms of the relevant intermolecular interactions.

Intramolecular torque, an indicator of the internal rotation direction of rotor molecules and similar systems.

Rotation-inducing torque is ubiquitous in many molecular systems. We present a straightforward theoretical method based on forces acting on atoms and obtained from atomistic quantum mechanics calculations to quickly and qualitatively determine whether a molecule or sub-unit thereof has a tendency to rotate and, if so, around which axis and in which sense: clockwise or counterclockwise. The method also indicates which atoms, if any, are predominant in causing the rotation.

Computational prediction of optimal metal ions to induce coordinated polymerization of muscle-like [c2]daisy chains.

Recently, a muscle-like organometallic polymer has been successfully synthesized using Fe(2+) as a linker atom. The polymer exhibits acid-base controllable muscle-like expansion and contraction on the micrometer scale. Further development could be facilitated by revealing the polymerization mechanism and by searching for optimal linker atoms.

Revealing highly unbalanced energy barriers in the extension and contraction of the muscle-like motion of a [c2]daisy chain.

Nanoscale muscle-like materials have aroused great interest as they may provide controllable mechanical operations by artificial actuations. Molecular designs to achieve the desired motion at the macroscopic scale in experiments require atomic level understanding. By systematic quantum chemical and molecular dynamics calculations we reveal that the length change is not only due to the linear telescoping from the dibenzo[24]crown-8 recognition at two docking stations but also the folding/unfolding of two bulky stoppers.

Analysis of the near-edge X-ray-absorption fine-structure of anthracene: a combined theoretical and experimental study.

The near-edge fine structure of the carbon K-edge absorption spectrum of anthracene was measured and theoretically analyzed by density functional theory calculations implemented in the StoBe code. It is demonstrated that the consideration of electronic relaxation of excited states around localized core holes yields a significant improvement of the calculated excitation energies and reproduces the experimentally observed fine structure well. The detailed analysis of excitation spectra calculated for each symmetry inequivalent excitation center allows in particular to examine the influence of chemical shifts and core hole effects on the excitation energies.

How strain affects the reactivity of surface metal oxide catalysts.

Highly dispersed molybdenum oxide supported on mesoporous silica SBA-15 has been prepared by anion exchange resulting in a series of catalysts with changing Mo densities (0.2-2.5 Mo atoms nm(-2) ).

Reduced skin reactivity to vasoconstrictor and vasodilator substances in atopic eczema.

Unlabelled: Atopic eczema is a common chronic inflammatory disease with itchy skin and altered skin reactions to acetylcholine and nicotinic acid compared to healthy non-atopic individuals.

Aim: The aim of this study was to evaluate skin reactivity to 11 vasoactive substances and peptides by skin prick and intradermal tests in 20 patients with atopic eczema and 20 healthy controls.

Methods: Skin reactions, blanching, wheal and flare areas were measured by planimetry, 15 minutes after provocation.

Periodic overlayers and moiré patterns: theoretical studies of geometric properties.

Single crystal surfaces with periodic overlayers, such as graphene on hexagonal metal substrates, are found to exhibit, apart from their intrinsic periodicity, additional long-range order expressed by approximate surface lattices with large lattice constants. This phenomenon can be described as geometrically analogous to lateral interference effects resulting in periodic moiré patterns which are characterized by two-dimensional moiré lattices. Here we discuss in detail the mathematical formalism determining such moiré patterns based on concepts of two-dimensional Fourier transformation including coincidence lattices.

Revision rates after total ankle arthroplasty in sample-based clinical studies and national registries.

Background: The aim of this study was to evaluate the outcome of specific implants in total ankle arthroplasty as reported in clinical studies and determined by national registries.

Materials And Methods: A structured literature review was conducted regarding sample-based clinical studies and national registry data. To allow for comparative analyses, registry data had to be available for the implants included.

Identification of the human/mouse syntenic common fragile site FRA7K/Fra12C1--relation of FRA7K and other human common fragile sites on chromosome 7 to evolutionary breakpoints.

Common fragile sites (CFSs) are expressed as chromosome gaps in cells of different species including human and mouse as a result of the inhibition of DNA replication. They may serve as hot spots for DNA breakage in processes such as tumorigenesis and chromosome evolution. Using multicolor fluorescence in situ hybridization mapping, the authors describe here human CFS FRA7K on chromosome band 7q31.

Common fragile sites are conserved features of human and mouse chromosomes and relate to large active genes.

Common fragile sites (CFSs) are seen as chromosomal gaps and breaks brought about by inhibition of replication, and it is thought that they cluster with tumor breakpoints. This study presents a comprehensive analysis using conventional and molecular cytogenetic mapping of CFSs and their expression frequencies in two mouse strains, BALB/c and C57BL/6, and in human probands. Here we show that induced mouse CFSs relate to sites of spontaneous gaps and breaks and that CFS expression levels in chromosome bands are conserved between the two mouse strains and between syntenic mouse and human DNA segments.

Molecular profiling of laser-microdissected matched tumor and normal breast tissue identifies karyopherin alpha2 as a potential novel prognostic marker in breast cancer.

Purpose: The aim of the present study was to identify human genes that might prove useful in the diagnosis and therapy of primary breast cancer.

Experimental Design: Twenty-four matched pairs of invasive ductal breast cancer and corresponding benign breast tissue were investigated by a combination of laser microdissection and gene expression profiling. Differential expression of candidate genes was validated by dot blot analysis of cDNA in 50 pairs of matching benign and malignant breast tissue.

Transcriptional census of 36 microdissected colorectal cancers yields a gene signature to distinguish UICC II and III.

UICC stage II and III colorectal cancers (CRC) differ fundamentally in prognosis and therapeutic concepts. To analyze differential gene expression between both stages and to establish a relationship between molecular background and clinical presentation, tumor material from 36 unselected consecutive patients presenting with sporadic CRC, 18 UICC stage II and 18 UICC stage III, were laser microdissected to separate epithelial tumor cells. Gene expression levels were measured using U133A Affymetrix gene arrays.

Critical influence of adsorption geometry in the heterogeneous epoxidation of "allylic" alkenes: structure and reactivity of three phenylpropene isomers on Cu(111).

It has long been conjectured that the difficulty of heterogeneously epoxidizing higher alkenes such as propene is due to the presence in the molecule of "allylic" H atoms that are readily stripped off by the oxygenated surface of the metal catalyst resulting in combustion. Here, taking advantage of the intrinsically higher epoxidation selectivity of Cu over Ag under vacuum conditions, we have used three phenylpropene structural isomers to examine the correlation between adsorption geometry and oxidation chemistry. It is found that under comparable conditions alpha-methylstyrene, trans-methylstyrene, and allylbenzene behave very differently on the oxygenated Cu(111) surface: the first undergoes extensive epoxidation accompanied by relatively little decomposition of the alkene; the second leads to some epoxide formation and extensive alkene decomposition; and the third is almost inert with respect to both reaction pathways.

The interaction of C6H6 and C6H12 with noble metal surfaces: electronic level alignment and the origin of the interface dipole.

The electronic interaction of two molecules, the aromatic benzene (C6H6) and the saturated hydrocarbon cyclohexane (C6H12) with a Cu(111) surface, have been determined using precise, ab initio electronic structure calculations. For the interaction of these adsorbates with the substrate, we present a detailed analysis and decomposition of various individual chemical mechanisms that contribute. A novel aspect of this analysis is the use of charge-density difference contour plots to graphically display the chemistry.

Loss of SFRP1 is associated with breast cancer progression and poor prognosis in early stage tumors.

Aberrant activation of the Wnt signaling pathway plays an important role in the development of solid tumors such as breast and colon cancer. Secreted Frizzled-related protein 1 (SFRP1) is a negative regulator of the Wnt pathway. It has been described that SFRP1 mRNA is strongly down-regulated in breast cancer and a putative tumor suppressor function has been postulated.

Changes in Angiotensin Peptides in Plasma and Urine in Patients with Anaphylaxis.

Angiotensins (ANG) I and II were measured in the plasma of patients with hymenoptera venom allergy and found to be significantly decreased as compared to controls. An inverse correlation between the plasma levels of ANG I and ANG II and the intensity of clinical symptoms of anaphylaxis was observed. In a separate study, ANG I and ANG II were measured in urine from healthy volunteers and from patients with anaphylactic reactions to drugs, food, and additives.