Transition-Metal-Doped NIR-Emitting Silicon Nanocrystals.

Impurity-doping in nanocrystals significantly affects their electronic properties and diversifies their applications. Herein, we report the synthesis of transition metal (Mn, Ni, Co, Cu)-doped oleophilic silicon nanocrystals (SiNCs) through hydrolysis/polymerization of triethoxysilane with acidic aqueous metal salt solutions, followed by thermal disproportionation of the resulting gel into a doped-Si/SiO composite that, upon HF etching and hydrosilylation with 1-n-octadecene, produces free-standing octadecyl-capped doped SiNCs (diameter≈3 to 8 nm; dopant <0.2 atom %).

Comparative effects of adaptation on layers II-III and V-VI neurons in cat V1.

V1 is fundamentally grouped into columns that descend from layers II-III to V-VI. Neurons inherent to visual cortex are capable of adapting to changes in the incoming stimuli that drive the cortical plasticity. A principle feature called orientation selectivity can be altered by the presentation of non-optimal stimulus called 'adapter'.

Nanostickers for cells: a model study using cell-nanoparticle hybrid aggregates.

We present direct evidence that nanoparticles (NPs) can stick together cells that are inherently non-adhesive. Using cadherin-depleted S180 murine cells lines, which exhibit very low cell-cell adhesion, we show that NPs can assemble dispersed single cells into large cohesive aggregates. The dynamics of aggregation, which is controlled by diffusion and collision, can be described as a second-order kinetic law characterized by a rate of collision that depends on the size, concentration, and surface chemistry of the NPs.

Refolding of Aggregation-Prone ScFv Antibody Fragments Assisted by Hydrophobically Modified Poly(sodium acrylate) Derivatives.

ScFv antibody fragments are a promising alternative to full-length antibodies for both therapeutic and diagnosis applications. They can be overexpressed in bacteria, which enables easy large scale production. Since scFv are artificial constructs, they are poorly soluble and prone to aggregation, which makes them difficult to manipulate and to refold.

A Systematic Review of Reported Exposure to Engineered Nanomaterials.

Background: Engineered nanomaterials (ENMs) have a large economic impact in a range of fields, but the concerns about health and safety of occupational activities involving nanomaterials have not yet been addressed. Monitoring exposure is an important step in risk management. Hence, the interest for reviewing studies that reported a potential for occupational exposure.

Regulation and production of Tcf, a cable-like fimbriae from Salmonella enterica serovar Typhi.

tcf (Typhi colonization factor) is one of the 12 putative chaperone/usher fimbrial clusters present in the Salmonella enterica serovar Typhi genome. We investigated the production, expression and regulation of tcf as well as its role during interaction with human cells. The tcf gene cluster was cloned and induced in Escherichia coli and S.

Boron nitride nanotubes as vehicles for intracellular delivery of fluorescent drugs and probes.

Aim: To evaluate the response of cells to boron nitride nanotubes (BNNTs) carrying fluorescent probes or drugs in their inner channel by assessment of the cellular localization of the fluorescent cargo, evaluation of the in vitro release and biological activity of a drug (curcumin) loaded in BNNTs.

Methods: Cells treated with curcumin-loaded BNNTs and stimulated with lipopolysaccharide were assessed for nitric oxide release and stimulation of IL-6 and TNF-α. The cellular trafficking of two cell-permeant dyes and a non-cell-permeant dye loaded within BNNTs was imaged.

Influence of Confinement on the Chain Conformation of Cyclic Poly(-isopropylacrylamide).

In thin and ultrathin supported films, the conformations of flexible linear polymer chains might be considerably confined, in particular, for film thicknesses smaller than a few times the radius of gyration. For ring polymers in solution or in melt, the radii of gyration are significantly reduced as compared to those of their linear counterparts. We study here the influence of geometrical confinement on the chain conformation of cyclic PNIPAM in silicon-supported films.

Poly(N-isopropylacrylamide) Phase Diagrams: Fifty Years of Research.

In 1968, Heskins and Guillet published the first systematic study of the phase diagram of poly(N-isopropylacrylamide) (PNIPAM), at the time a "young polymer" first synthesized in 1956. Since then, PNIPAM became the leading member of the growing families of thermoresponsive polymers and of stimuli-responsive, "smart" polymers in general. Its thermal response is unanimously attributed to its phase behavior.

Pharmacological Mechanisms of Cortical Enhancement Induced by the Repetitive Pairing of Visual/Cholinergic Stimulation.

Repetitive visual training paired with electrical activation of cholinergic projections to the primary visual cortex (V1) induces long-term enhancement of cortical processing in response to the visual training stimulus. To better determine the receptor subtypes mediating this effect the selective pharmacological blockade of V1 nicotinic (nAChR), M1 and M2 muscarinic (mAChR) or GABAergic A (GABAAR) receptors was performed during the training session and visual evoked potentials (VEPs) were recorded before and after training. The training session consisted of the exposure of awake, adult rats to an orientation-specific 0.

Formation of Tethers from Spreading Cellular Aggregates.

Membrane tubes are commonly extruded from cells and vesicles when a point-like force is applied on the membrane. We report here the unexpected formation of membrane tubes from lymph node cancer prostate (LNCaP) cell aggregates in the absence of external applied forces. The spreading of LNCaP aggregates deposited on adhesive glass substrates coated with fibronectin is very limited because cell-cell adhesion is stronger than cell-substrate adhesion.

Network-selectivity and stimulus-discrimination in the primary visual cortex: cell-assembly dynamics.

Visual neurons coordinate their responses in relation to the stimulus; however, the complex interplay between a stimulus and the functional dynamics of an assembly still eludes neuroscientists. To this aim, we recorded cell assemblies from multi-electrodes in the primary visual cortex of anaesthetized cats in response to randomly presented sine-wave drifting gratings whose orientation tilted in 22.5° steps.

Overview on Sleep Bruxism for Sleep Medicine Clinicians.

Sleep bruxism (SB) is a common sleep-related jaw motor disorder observed in 8% of the adult population. SB diagnosis is based on history of tooth grinding and clenching and is confirmed by the polysomnographic recording of the electromyographic activity of jaw muscles during sleep. SB may be associated with orofacial pain, headaches, and sleep-disordered breathing.

Stimulus-dependent augmented gamma oscillatory activity between the functionally connected cortical neurons in the primary visual cortex.

Neuronal assemblies typically synchronise within the gamma oscillatory band (30-80 Hz) and are fundamental to information processing. Despite numerous investigations, the exact mechanisms and origins of gamma oscillations are yet to be known. Here, through multiunit recordings in the primary visual cortex of cats, we show that the strength of gamma power (20-40 and 60-80 Hz) is significantly stronger between the functionally connected units than between the unconnected units within an assembly.

Modulation of extracellular ATP content of mast cells and DRG neurons by irradiation: studies on underlying mechanism of low-level-laser therapy.

Low-level-laser therapy (LLLT) is an effective complementary treatment, especially for anti-inflammation and wound healing in which dermis or mucus mast cells (MCs) are involved. In periphery, MCs crosstalk with neurons via purinergic signals and participate in various physiological and pathophysiological processes. Whether extracellular ATP, an important purine in purinergic signaling, of MCs and neurons could be modulated by irradiation remains unknown.

Strong antibacterial properties of anion transporters: a result of depolarization and weakening of the bacterial membrane.

The development of low molecular weight anionophores is an emerging topic in chemistry, as the need for these compounds increases with the continuous discovery of pathologies involving anomalies in anion transport processes. Development of new concepts to initiate anion imbalance in living cells while fighting multidrug-resistant bacteria is a paramount topic. In this study, three series of compounds including N,N'-diphenylethynylbenzyl benzimidazolium salts (1 and 2), 1,1'-(pyridine-2,6-diyl)bis(3-(4-(phenylethynyl)benzyl)-1H-benzo[d]imidazol-3-ium) salts (3-5), and 1,1'-(pyridine-2,6-diylbis(methylene))bis(3-(4-(phenyl ethynyl)benzyl)-1H-benzo[d]imidazol-3-ium) salts (6-8) displaying high antimicrobial activity and low toxicity against human cells were designed, synthesized, and studied.

Tethered poly(2-isopropyl-2-oxazoline) chains: temperature effects on layer structure and interactions probed by AFM experiments and modeling.

Thermoresponsive polymer layers on silica surfaces have been obtained by utilizing electrostatically driven adsorption of a cationic-nonionic diblock copolymer. The cationic block provides strong anchoring to the surface for the nonionic block of poly(2-isopropyl-2-oxazoline), referred to as PIPOZ. The PIPOZ chain interacts favorably with water at low temperatures, but above 46 °C aqueous solutions of PIPOZ phase separate as water becomes a poor solvent for the polymer.

Phosphorylcholine-modified chitosan films as effective promoters of cell aggregation: correlation between the films properties and cellular response.

This study describes chitosan-phosphorylcholine (CH-PC) films able to support the formation of cell aggregates (spheroids), which are important for tissue engineering and pharmacological studies. The surface topography, charge, thickness, and rheology of CH-PC thin films were characterized by AFM, zeta-potential measurements, SPR spectroscopy, and QCM-D measurements. The CH-PC films are highly hydrated gels, independently of the level of PC incorporation (15-40 mol-% PC/glucosamine units).

Biological reformation of ethanol to hydrogen by Rhodopseudomonas palustris CGA009.

A future hydrogen economy requires the sustainable production of renewable hydrogen. One method to produce hydrogen from stored renewable energy could be through reformation of bioethanol. However, chemically catalyzed reformation processes, although well studied, still present a number of significant technical challenges.

Optimized triazine-mediated amidation for efficient and controlled functionalization of hyaluronic acid.

Triazine-based coupling agents have the potential to replace carbodiimides in the functionalization of hyaluronic acid (HA) giving derivatives with high degrees of substitution (DS) under mild conditions with excellent efficiency. Kinetics of the triazine-mediated amidation of HA in aqueous solution were investigated to understand the reaction mechanism and the role of the amine reagent. The DS decreased with increasing basicity of the amine.

Life-stage differences in spatial genetic structure in an irruptive forest insect: implications for dispersal and spatial synchrony.

Dispersal determines the flux of individuals, energy and information and is therefore a key determinant of ecological and evolutionary dynamics. Yet, it remains difficult to quantify its importance relative to other factors. This is particularly true in cyclic populations in which demography, drift and dispersal contribute to spatio-temporal variability in genetic structure.

Quantitative characterization by asymmetrical flow field-flow fractionation of IgG thermal aggregation with and without polymer protective agents.

Complexes formed between poly(acrylates) and polyclonal immunoglobulin G (IgG) in its native conformation and after heat stress were characterized using asymmetric flow field-flow fractionation (AF4) coupled with on-line UV-Vis spectroscopy and multi-angle light-scattering detection (MALS). Mixtures of IgG and poly(acrylates) of increasing structural complexity, sodium poly(acrylate) (PAA), a sodium poly(acrylate) bearing at random 3 mol % n-octadecyl groups, and a random copolymer of sodium acrylate (35 mol%), N-n-octylacrylamide (25 mol%) and N-isopropylacrylamide (40 mol%), were fractionated in a sodium phosphate buffer (0.02 M, pH 6.

Prediction of poor outcomes six months following total knee arthroplasty in patients awaiting surgery.

Background: Identification of patients experiencing poor outcomes following total knee arthroplasty (TKA) before the intervention could allow better case selection, patient preparation and, likely, improved outcomes. The objective was to develop a preliminary prediction rule (PR) to identify patients enrolled on surgical wait lists who are at the greatest risk of poor outcomes 6 months after TKA.

Methods: 141 patients scheduled for TKA were recruited prospectively from the wait lists of 3 hospitals in Quebec City, Canada.

Repetitive and retinotopically restricted activation of the dorsal lateral geniculate nucleus with optogenetics.

Optogenetics allows the control of cellular activity using focused delivery of light pulses. In neuroscience, optogenetic protocols have been shown to efficiently inhibit or stimulate neuronal activity with a high temporal resolution. Among the technical challenges associated with the use of optogenetics, one is the ability to target a spatially specific population of neurons in a given brain structure.