Quantitative Model of Multiple Crystal Growth Rate Minima in Polymers with Regularly Spaced Substituent Groups.

A simple theory has been developed to explain quantitatively the multiple crystal growth rate minima observed experimentally in polyethylene brassylates (PEBs), polymers with regularly spaced "chemical defects", in this case, diester groups separated by 11 methylenes. The minima occur at the transitions where the fold length drops from 4 to 3 repeat units and from 3 to 2 units. An analytical rate-equation model was developed with elementary attachment and detachment steps of individual monomer repeat units, also including postattachment stem lengthening (stem conversion).

Systemic review of age brackets in pediatric emergency medicine literature and the development of a universal age classification for pediatric emergency patients - the Munich Age Classification System (MACS).

Currently arbitrary, inconsistent and non-evidence-based age cutoffs are used in the literature to classify pediatric emergencies. None of these classifications have valid medical rationale. This leads to confusion and poor comparability of the different study results.

A case of antiferrochirality in a liquid crystal phase of counter-rotating staircases.

Helical structures continue to inspire, prompted by examples such as DNA double-helix and alpha-helix in proteins. Most synthetic polymers also crystallize as helices, which relieves steric clashes by twisting, while keeping the molecules straight for their ordered packing. In columnar liquid crystals, which often display useful optoelectronic properties, overall helical chirality can be induced by inclusion of chiral chemical groups or dopants; these bias molecular twist to either left or right, analogous to a magnetic field aligning the spins in a paramagnet.

Quasi-continuous melting of model polymer monolayers prompts reinterpretation of polymer melting.

Condensed matter textbooks teach us that melting cannot be continuous and indeed experience, including with polymers and other long-chain compounds, tells us that it is a strongly first-order transition. However, here we report nearly continuous melting of monolayers of ultralong n-alkane CH on graphite, observed by AFM and reproduced by mean-field theory and MD simulation. On heating, the crystal-melt interface moves steadily and reversibly from chain ends inward.

Specific composition of polyphenolic compounds with fatty acids as an approach in helping to reduce spirochete burden in Lyme disease: and human observational study.

Background: Lyme disease (LD) is a tick-borne infection caused by sensu lato. The current therapeutic approach to this disease is limited to antibiotics. However, after their administration, about 20% of patients experience delayed onset of this illness manifesting as lingering persistent symptoms.

Competing magnetic effects due to the incorporation of oxygen in thin films of (ZnCo)O.

We have investigated the magnetic properties of ZnCoO thin films grown by pulsed laser deposition from targets made from pure ZnO combined with metallic Co, CoO or CoO as a function of oxygen pressure in the deposition chamber. We find that the structural and magnetic properties of films grown from targets containing CoO or CoO are similar and can be mapped on to each other by assuming that the films made from CoO require some additional oxygen to make them the same as those grown from CoO. The data suggest that the magnetism in these films is due to oxygen vacancies.

Molecular ejection transition in liquid crystal columns self-assembled from wedge-shaped minidendrons.

Fan-shaped molecules with aromatic head-groups and two or more flexible pendant chains often self-assemble into columns that form columnar liquid crystals by packing on a 2d lattice. Such dendrons or minidendrons are essential building blocks in a large number of synthetic self-assembled systems and organic device materials. Here we report a new type of phase transition that occurs between two hexagonal columnar phases, Colh1 and Colh2, of Na-salt of 3,4,5-tris-dodecyloxy benzoic acid.

Monte Carlo study of the ordering in a strongly frustrated liquid crystal.

We have performed Monte Carlo simulations to investigate the temperature dependence of the ordering of the side chains of the X-shaped liquid crystal molecules which are arranged in a hexagonal array. Each hexagon contains six side chains, one from each side of the hexagon. Each liquid crystal molecule has two, dissimilar, side chains, one that contains silicon and one that contains fluorine.

Morphology and magnetic properties of Fe3O 4 nanodot arrays using template-assisted epitaxial growth.

Arrays of epitaxial Fe3O4 nanodots were prepared using laser molecular beam epitaxy (LMBE), with the aid of ultrathin porous anodized aluminum templates. An Fe3O4 film was also prepared using LMBE. Atomic force microscopy and scanning electron microscopy images showed that the Fe3O4 nanodots existed over large areas of well-ordered hexagonal arrays with dot diameters (D) of 40, 70, and 140 nm; height of approximately 20 nm; and inter-dot distances (D int) of 67, 110, and 160 nm.

The clinically approved drugs amiodarone, dronedarone and verapamil inhibit filovirus cell entry.

Objectives: Filoviruses such as Ebola virus and Marburg virus cause a severe haemorrhagic fever syndrome in humans for which there is no specific treatment. Since filoviruses use a complex route of cell entry that depends on numerous cellular factors, we hypothesized that there may be drugs already approved for human use for other indications that interfere with signal transduction or other cellular processes required for their entry and hence have anti-filoviral properties.

Methods: We used authentic filoviruses and lentiviral particles pseudotyped with filoviral glycoproteins to identify and characterize such compounds.

Enhanced room temperature magnetoresistance and spin injection from metallic cobalt in Co/ZnO and Co/ZnAlO films.

Co/ZnO and Co/ZnAlO films were prepared by depositing ultrathin cobalt layers and semiconductor layers on glass substrates at room temperature. The films consist of metallic Co particles, semiconductor matrix, and an interfacial magnetic semiconductor with the substitution of Co(2+) for Zn(2+) in the ZnO lattice at the interface between Co particles and the semiconductor matrix. Large room temperature negative tunneling magnetoresistance was observed in the films.

Complex multicolor tilings and critical phenomena in tetraphilic liquid crystals.

T-shaped molecules with a rod-like aromatic core and a flexible side chain form liquid crystal honeycombs with aromatic cell walls and a cell interior filled with the side chains. Here, we show how the addition of a second chain, incompatible with the first (X-shaped molecules), can form honeycombs with highly complex tiling patterns, with cells of up to five different compositions ("colors") and polygonal shapes. The complexity is caused by the inability of the side chains to separate cleanly because of geometric frustration.

Volumetric diffusers: pseudorandom cylinder arrays on a periodic lattice.

Most conventional diffusers take the form of a surface based treatment, and as a result can only operate in hemispherical space. Placing a diffuser in the volume of a room might provide greater efficiency by allowing scattering into the whole space. A periodic cylinder array (or sonic crystal) produces periodicity lobes and uneven scattering.

Tunable optical time delay of quantum signals using a prism pair.

We describe a compact, tunable, optical time-delay module that functions by means of total internal reflection within two glass prisms. The delay is controlled by small mechanical motions of the prisms. The device is inherently extremely broad band, unlike time delay modules based on "slow light" methods.

Diffusive benefits of cylinders in front of a Schroeder diffuser.

A numerical investigation is performed into the diffusive effects of cylinders positioned in front of a Schroeder diffuser. A regular line of cylinders is shown to offer notable improvements to diffusion from a periodic Schroeder device, provided lateral cylinder spacing is incommensurable with the Schroeder period width. Further investigation considers angular dependence and low frequency results in greater detail, as well as the effects on narrowband and modulated Schroeder devices.

Magnetoresistance of magnetically doped ZnO films.

Magnetoresistance measurements have been made at 5 K on doped ZnO thin films grown by pulsed laser deposition. ZnCoO, ZnCoAlO and ZnMnAlO samples have been investigated and compared to similar films containing no transition metal dopants. It is found that the Co-doped samples with a high carrier concentration have a small negative magnetoresistance, irrespective of their magnetic moment.

Two magnetic regimes in doped ZnO corresponding to a dilute magnetic semiconductor and a dilute magnetic insulator.

Films of ZnO doped with magnetic ions Mn and Co and, in some cases, with Al have been fabricated with a very wide range of carrier densities. Ferromagnetic behavior is observed in both insulating and metallic films, but not when the carrier density is intermediate. Insulating films exhibit variable range hopping at low temperatures and are ferromagnetic at room temperature due to the interaction of the localized spins with static localized states.

Reducing pulse distortion in fast-light pulse propagation through an erbium-doped fiber amplifier.

When a pulse superposed on a cw background propagates through an erbium-doped fiber amplifier with a negative group velocity, either pulse broadening or pulse compression can be observed. These effects can be explained in terms of two competing mechanisms: gain recovery and pulse spectrum broadening. The distortion of the pulse shape caused by these effects depends on input pulse width, pump power, and background-to-pulse power ratio.

Room-temperature magneto-optics of ferromagnetic transition-metal-doped ZnO thin films.

Magneto-optic studies of ZnO doped with transition metals Co, Mn, V, and Ti indicate a significant magnetic circular dichroism (MCD) at the ZnO band edge at room temperature, together with an associated dispersive Faraday rotation. Similar spectra occur for each dopant, which implies that the ferromagnetism is an intrinsic property of the bulk ZnO lattice. At 10 K, additional paramagnetic contributions to the MCD are observed, but above about 150 K, the magnitude of the MCD signal is dominated by the ferromagnetism and is almost temperature independent.

Observation of backward pulse propagation through a medium with a negative group velocity.

The nature of pulse propagation through a material with a negative value of the group velocity has been mysterious, as simple models seem to predict that pulses will propagate "backward" through such a material. Using an erbium-doped optical fiber and measuring the time evolution of the pulse intensity at many points within the fiber, we demonstrate that the peak of the pulse does propagate backward inside the fiber, even though the energy flow is always in the forward direction.

Ferromagnetism above room temperature in bulk and transparent thin films of Mn-doped ZnO.

The search for ferromagnetism above room temperature in dilute magnetic semiconductors has been intense in recent years. We report the first observations of ferromagnetism above room temperature for dilute (<4 at.%) Mn-doped ZnO.

The Fermi surface of [Formula: see text].

The heavy-fermion compound [Formula: see text] has been studied using the fully relativistic spin-polarized mean muffin-tin orbital method within the local density approximation. Two separate calculations, one where the f electron is treated as a valence electron and the other where it is treated as part of the core, have been performed and the Fermi surface is obtained. The angular-dependent de Haas - van Alphen (dHvA) frequencies are calculated in both cases and they are compared with the experimental dHvA frequencies.