Crossover behavior of the thermal conductance and Kramers' transition rate theory.

Kramers' theory frames chemical reaction rates in solution as reactants overcoming a barrier in the presence of friction and noise. For weak coupling to the solution, the reaction rate is limited by the rate at which the solution can restore equilibrium after a subset of reactants have surmounted the barrier to become products. For strong coupling, there are always sufficiently energetic reactants.

Coassemblies of the Anionic Polypeptide γ-PGA and Cationic β-Sheet Peptides for Drug Delivery to Mitochondria.

The effectiveness of a drug may be highly dependent on its delivery to its target organ and even to specific intracellular organelles. In this study we developed nanoparticles (NPs) composed of the anionic polypeptide poly-γ-glutamic acid (γ-PGA), and a designed amphiphilic and cationic β-sheet peptide (PFK), which tends to form fibril bilayer assemblies. These peptide assemblies generate hydrophobic niches within the NPs, which enhance the NPs' capacity to deliver amphiphilic drugs.

PbS nanosculptured thin film for phase retarder, anti-reflective, excellent absorber, polarizer and sensor applications.

Lead-sulphide (PbS) nanosculptured thin film (nSTF) is prepared using a glancing angle deposition (GLAD) technique and the physical vapour deposition (PVD) process. The morphology of the GLAD films clearly shows that an anisotropic structure is obtained and is composed of micro-sheets with sharp top edges (a few tens of nanometres tip width). Due to this anisotropy, optical birefringence is induced in the nSTF as well as linear dichroism.

Hierarchical multi-step organization during viral capsid assembly.

Formation of the HIV-1 core by the association of capsid proteins is a critical, not fully understood, step in the viral life cycle. Understanding the early stages of the mechanism may improve treatment opportunities. Here, spectroscopic analysis (opacity) is used to follow the kinetics of capsid protein assembly, which shows three stages: a lag phase, followed by a linear increase stage and terminated by a plateau.

Nucleosome Core Particle Disassembly and Assembly Kinetics Studied Using Single-Molecule Fluorescence.

The stability of the nucleosome core particle (NCP) is believed to play a major role in regulation of gene expression. To understand the mechanisms that influence NCP stability, we studied stability and dissociation and association kinetics under different histone protein (NCP) and NaCl concentrations using single-pair Förster resonance energy transfer and alternating laser excitation techniques. The method enables distinction between folded, unfolded, and intermediate NCP states and enables measurements at picomolar to nanomolar NCP concentrations where dissociation and association reactions can be directly observed.

Non-Amyloid-β Component of Human α-Synuclein Oligomers Induces Formation of New Aβ Oligomers: Insight into the Mechanisms That Link Parkinson's and Alzheimer's Diseases.

Parkinson's disease (PD) is characterized by the formation of Lewy bodies (LBs), of which their major component is the non-amyloid-β component (NAC) of α-synuclein (AS). Clinical studies have identified a link between PD and Alzheimer's disease (AD), but the question of why PD patients are at risk to develop various types of dementia, such as AD, is still elusive. In vivo studies have shown that Aβ can act as a seed for NAC/AS aggregation, promoting NAC/AS aggregation and thus contributing to the etiology of PD.

Graphene-Based Hybrid Composites for Efficient Thermal Management of Electronic Devices.

Thermal management has become a critical aspect in next-generation miniaturized electronic devices. Efficient heat dissipation reduces their operating temperatures and insures optimal performance, service life, and efficacy. Shielding against shocks, vibrations, and moisture is also imperative when the electronic circuits are located outdoors.

Enhancement in the excitonic spontaneous emission rates for Si nanocrystal multi-layers covered with thin films of Au, Ag, and Al.

The enhancement in the spontaneous emission rate (SER) for Ag, Au, and Al films on multilayer Si nanocrystals (SiNCs) was probed with time-resolved cathodoluminescence (CL). The SiNCs were grown on Si(100) using plasma enhanced chemical vapor deposition. Electron-hole pairs were generated in the metal-covered SiNCs by injecting a pulsed high-energy electron beam through the thin metal films, which is found to be an ideal method of excitation for plasmonic quantum heterostructures and nanostructures that are opaque to laser or light excitation.

Amylin-Aβ oligomers at atomic resolution using molecular dynamics simulations: a link between Type 2 diabetes and Alzheimer's disease.

Clinical studies have identified Type 2 diabetes (T2D) as a risk factor of Alzheimer's disease (AD). One of the potential mechanisms that link T2D and AD is the loss of cells associated with degenerative changes. Amylin1-37 aggregates (the pathological species in T2D) were found to be co-localized with those of Aβ1-42 (the pathological species in AD) to form the Amylin1-37-Aβ1-42 plaques, promoting aggregation and thus contributing to the etiology of AD.

Biocomposite based on reduced graphene oxide film modified with phenothiazone and flavin adenine dinucleotide-dependent glucose dehydrogenase for glucose sensing and biofuel cell applications.

A novel composite material for the encapsulation of redox enzymes was prepared. Reduced graphene oxide film with adsorbed phenothiazone was used as a highly efficient composite for electron transfer between flavin adenine dinucleotide (FAD)-dependent glucose dehydrogenase and electrodes. Measured redox potential for glucose oxidation was lower than 0 V vs Ag/AgCl electrode.

Photocatalytic hybrid Au/ZnO nanoparticles assembled through a one-pot method.

Growth of metal domains on semiconductor nanoparticles is known to enhance their photocatalytic properties. We prepared ZnO nanoparticles decorated with metallic Au domains through a new one-pot microwave-based strategy. The synthetic route utilized microwave-heating of a mixture of only three components: Zn(2+) salt, Au(SCN)4(-) which served as a precursor for metallic gold, and Tris base.

Static laser speckle contrast analysis for noninvasive burn diagnosis using a camera-phone imager.

Laser speckle contrast analysis (LASCA) is an established optical technique for accurate widefield visualization of relative blood perfusion when no or minimal scattering from static tissue elements is present, as demonstrated, for example, in LASCA imaging of the exposed cortex. However, when LASCA is applied to diagnosis of burn wounds, light is backscattered from both moving blood and static burn scatterers, and thus the spatial speckle contrast includes both perfusion and nonperfusion components and cannot be straightforwardly associated to blood flow. We extract from speckle contrast images of burn wounds the nonperfusion (static) component and discover that it conveys useful information on the ratio of static-to-dynamic scattering composition of the wound, enabling identification of burns of different depth in a porcine model in vivo within the first 48 h postburn.

Surface plasmon resonance in surfactant coated copper sulfide nanoparticles: Role of the structure of the capping agent.

Hypothesis: The optical properties of as-synthesized CuS nanoparticles are affected by shape, size and morphology and exhibit increased optical absorbance in the infrared range due to localized surface plasmon resonance (LSPR), which is also affected by these parameters. An additional parameter which affects the LSPR-related absorbance is crystallinity of the surfactant coating.

Experiments: CuS nanoparticles with varying morphologies were synthesized using a single source, single surfactant/solvent route.

A Proposed Atomic Structure of the Self-Assembly of the Non-Amyloid-β Component of Human α-Synuclein As Derived by Computational Tools.

α-Synuclein (AS) fibrils are the major hallmarks of Parkinson's disease (PD). It is known that the central domain of the 140-residue AS protein, known as the non-amyloid-β component (NAC), plays a crucial role in aggregation. The secondary structure of AS fibrils (including the NAC domain) has been proposed on the basis of solid-state nuclear magnetic resonance studies, but the atomic structure of the self-assembly of NAC (or AS itself) is still elusive.

Introducing improved structural properties and salt dependence into a coarse-grained model of DNA.

We introduce an extended version of oxDNA, a coarse-grained model of deoxyribonucleic acid (DNA) designed to capture the thermodynamic, structural, and mechanical properties of single- and double-stranded DNA. By including explicit major and minor grooves and by slightly modifying the coaxial stacking and backbone-backbone interactions, we improve the ability of the model to treat large (kilobase-pair) structures, such as DNA origami, which are sensitive to these geometric features. Further, we extend the model, which was previously parameterised to just one salt concentration ([Na(+)] = 0.

Observations of exciton-surface plasmon polariton coupling and exciton-phonon coupling in InGaN/GaN quantum wells covered with Au, Ag, and Al films.

The coupling of excitons to surface plasmon polaritons (SPPs) and longitudinal optical (LO) phonons in Au-, Ag-, and Al-coated InxGa1-xN/GaN multiple and single quantum wells (SQWs) was studied with time-resolved cathodoluminescence (CL) and CL wavelength imaging techniques. Excitons were generated in the metal-coated SQWs by injecting a pulsed high-energy electron beam through the thin metal films, which is found to be an ideal method of excitation for plasmonic quantum heterostructures and nanostructures which are opaque to laser/light excitation. The Purcell enhancement factor (Fp) at low temperatures was obtained by the direct measurement of changes in the carrier lifetime caused by the SQW exciton-SPP coupling.

The Use of Yeast Surface Display in Biofuel Cells.

Biofuel cells are electrochemical devices which convert chemical energy to electricity using biochemical pathways and redox enzymes. In enzymatic fuel cells purified redox enzymes catalyze the reactions in the anode and cathode compartments whereas in microbial fuel cells (MFCs) the entire metabolism of the microorganisms is exploited. Here, a hybrid biofuel cell concept is presented, which is based on yeast surface display (YSD) of redox enzymes to catalyze the different cell reactions.

Crystal structure of the magnetobacterial protein MtxA C-terminal domain reveals a new sequence-structure relationship.

Magnetotactic bacteria (MTB) are a diverse group of aquatic bacteria that have the magnetotaxis ability to align themselves along the geomagnetic field lines and to navigate to a microoxic zone at the bottom of chemically stratified natural water. This special navigation is the result of a unique linear assembly of a specialized organelle, the magnetosome, which contains a biomineralized magnetic nanocrystal enveloped by a cytoplasmic membrane. The Magnetospirillum gryphiswaldense MtxA protein (MGR_0208) was suggested to play a role in bacterial magnetotaxis due to its gene location in an operon together with putative signal transduction genes.

Mitotic slippage and expression of survivin are linked to differential sensitivity of human cancer cell-lines to the Kinesin-5 inhibitor monastrol.

The mitotic Kinesin-5 motor proteins crosslink and slide apart antiparallel spindle microtubules, thus performing essential functions in mitotic spindle dynamics. Specific inhibition of their function by monastrol-like small molecules has been examined in clinical trials as anticancer treatment, with only partial success. Thus, strategies that improve the efficiency of monastrol-like anticancer drugs are required.

Deletion of the Tail Domain of the Kinesin-5 Cin8 Affects Its Directionality.

The bipolar kinesin-5 motors are one of the major players that govern mitotic spindle dynamics. Their bipolar structure enables them to cross-link and slide apart antiparallel microtubules (MTs) emanating from the opposing spindle poles. The budding yeast kinesin-5 Cin8 was shown to switch from fast minus-end- to slow plus-end-directed motility upon binding between antiparallel MTs.

Alginate biomaterial for the treatment of myocardial infarction: Progress, translational strategies, and clinical outlook: From ocean algae to patient bedside.

Alginate biomaterial is widely utilized for tissue engineering and regeneration due to its biocompatibility, non-thrombogenic nature, mild and physical gelation process, and the resemblance of its hydrogel matrix texture and stiffness to that of the extracellular matrix. In this review, we describe the versatile biomedical applications of alginate, from its use as a supporting cardiac implant in patients after acute myocardial infarction (MI) to its employment as a vehicle for stem cell delivery and for the controlled delivery and presentation of multiple combinations of bioactive molecules and regenerative factors into the heart. Preclinical and first-in-man clinical trials are described in details, showing the therapeutic potential of injectable acellular alginate implants to inhibit the damaging processes after MI, leading to myocardial repair and tissue reconstruction.

The role of steric interactions in dispersion of carbon nanotubes by poly(3-alkyl thiophenes) in organic solvents.

The dispersion mechanism of carbon nanotubes (CNTs) in organic solutions of poly(3-alkyl thiophenes, P3ATs) was examined in a study that combines experimental investigation of the dispersion mechanism and molecular theory calculations of the effective intertube potential for polymer wrapped CNTs. The minimal polymer concentration required for dispersion of CNT served as a comparative measure of the efficiency of P3AT derivatives that differ in the length of the alkyl side chains or the regiochemistry of the monomers in three solvents: 1,2 and 1,3 dichlorobenzene and chloroform. While previous studies focused on the adsorption mechanism of P3ATs onto SWNT, we find that the dispersing efficiency depends not only on the stacking of the polymer backbone onto the CNT ("wrapping"), but also on the steric repulsion among the side chains of adsorbed P3ATs.

Laser speckle spatiotemporal variance analysis for noninvasive widefield measurements of blood pulsation and pulse rate on a camera-phone.

Photoplethysmography is a well-established technique for the noninvasive measurement of blood pulsation. However, photoplethysmographic devices typically need to be in contact with the surface of the tissue and provide data from a single contact point. Extensions of conventional photoplethysmography to measurements over a wide field-of-view exist, but require advanced signal processing due to the low signal-to-noise-ratio of the photoplethysmograms.

Small membranes under negative surface tension.

We use computer simulations and a simple free energy model to study the response of a bilayer membrane to the application of a negative (compressive) mechanical tension. Such a tension destabilizes the long wavelength undulation modes of giant vesicles, but it can be sustained when small membranes and vesicles are considered. Our negative tension simulation results reveal two regimes-(i) a weak negative tension regime characterized by stretching-dominated elasticity and (ii) a strong negative tension regime featuring bending-dominated elastic behavior.