Label-Free Single Nanoparticle Identification and Characterization in Demanding Environment, Including Infectious Emergent Virus.

Unknown particle screening-including virus and nanoparticles-are keys in medicine, industry, and also in water pollutant determination. Here, RYtov MIcroscopy for Nanoparticles Identification (RYMINI) is introduced, a staining-free, non-invasive, and non-destructive optical approach that is merging holographic label-free 3D tracking with high-sensitivity quantitative phase imaging into a compact optical setup. Dedicated to the identification and then characterization of single nano-object in solution, it is compatible with highly demanding environments, such as level 3 biological laboratories, with high resilience to external source of mechanical and optical noise.

Viscoelasticity of Low-Molecular-Weight Polyelectrolytes.

Shear-thickening fluids that absorb the impact energy of high-velocity projectiles are of great interest for aerospace and body-armor applications. In such a frame, we investigate transient states of neat and aqueous polyelectrolytes (PE) having low molecular weights and containing poly([2-(methacryloyloxy)ethyl]trimethylammonium) as polycations and poly(acrylamide--acrylic acid) as polyanions. We compare results with those of bulk water.

Neat and Aqueous Polyelectrolytes under a Steady-Shear Flow.

Materials enabling impact-energy absorption of high-velocity projectiles are of great interest for applications like aerospace. In such a frame, shear thickening fluids were found very useful. Here, we investigated nanorheological properties of neat and aqueous polyelectrolytes of low molecular weights containing poly([2-(methacryloyloxy) ethyl] trimethyl ammonium) as polycations and poly(acrylamide--acrylic acid) as polyanions.

Douglas fir stimulates nitrification in French forest soils.

Douglas fir trees presumable stimulate nitrification in the soil. We studied in 21 French Douglas fir forests if and how nitrification is modulated by soil properties, past land use and current forest management. Soil (0-10 cm depth) was collected and initial concentrations of N-NH and N-NO, potential net nitrogen mineralization (PNM) and net nitrification (PNN) rates and microbial biomass were measured.

Impact of vegetation on the methane budget of a temperate forest.

Upland forest soils are known to be the main biological sink for methane, but studies have shown that net methane uptake of a forest ecosystem can be reduced when methane emissions by vegetation are considered. We estimated the methane budget of a young oak plantation by considering tree stems but also the understorey vegetation. Automated chambers connected to a laser-based gas analyser, on tree stems, bare soil and soil covered with understorey vegetation, recorded CH fluxes for 7 months at 3 h intervals.

Effect of the Titanium Nanoparticle on the Quantum Chemical Characterization of the Liquid Sodium Nanofluid.

Suspension state of a titanium nanoparticle in the liquid sodium was quantum chemically characterized by comparing physical characteristics, viz., electronic state, viscosity, and surface tension, with those of liquid sodium. The exterior titanium atoms on the topmost facet of the nanoparticle were found to constitute a stable Na-Ti layer, and the Brownian motion of a titanium nanoparticle could be seen in tandem with the surrounding sodium atoms.

Interaction grand potential between calcium-silicate-hydrate nanoparticles at the molecular level.

Calcium-silicate-hydrate (or C-S-H), an inosilicate, is the major binding phase in cement pastes and concretes and a porous hydrated material made up of a percolated and dense network of crystalline nanoparticles of a mean apparent spherical diameter of ∼5 nm that are each stacks of multiple C-S-H layers. Interaction forces between these nanoparticles are at the origin of C-S-H chemical, physical, and mechanical properties at the meso- and macroscales. These particle interactions and the resulting properties may be affected significantly by nanoparticle density and environmental conditions such as the temperature, relative humidity, or concentration of chemical species in the bulk solution.

Solvated calcium ions in charged silica nanopores.

Hydroxyl surface density in porous silica drops down to nearly zero when the pH of the confined aqueous solution is greater than 10.5. To study such extreme conditions, we developed a model of slit silica nanopores where all the hydrogen atoms of the hydroxylated surface are removed and the negative charge of the resulting oxygen dangling bonds is compensated by Ca(2+) counterions.

Thermodynamics of water confined in porous calcium-silicate-hydrates.

Water within pores of cementitious materials plays a crucial role in the damage processes of cement pastes, particularly in the binding material comprising calcium-silicate-hydrates (C-S-H). Here, we employed Grand Canonical Monte Carlo simulations to investigate the properties of water confined at ambient temperature within and between C-S-H nanoparticles or "grains" as a function of the relative humidity (%RH). We address the effect of water on the cohesion of cement pastes by computing fluid internal pressures within and between grains as a function of %RH and intergranular separation distance, from 1 to 10 Å.

Molecular simulation of water confined in nanoporous silica.

This paper reports on a molecular simulation study of the thermodynamics, structure and dynamics of water confined at ambient temperature in hydroxylated silica nanopores of a width H = 10 and 20 Å. The adsorption isotherms for water in these nanopores resemble those observed for experimental samples; the adsorbed amount increases continuously in the multilayer adsorption regime until a jump occurs due to capillary condensation of the fluid within the pore. Strong layering of water in the vicinity of the silica surfaces is observed as marked density oscillations are observed up to 8 Å from the surface in the density profiles for confined water.

Anisotropic united atom model including the electrostatic interactions of benzene.

An optimization including electrostatic interactions has been performed for the parameters of an anisotropic united atoms intermolecular potential for benzene for thermodynamic and transport property prediction using Gibbs ensemble, isothermal-isobaric (NPT) Monte Carlo, and molecular dynamic simulations. The optimization procedure is based on the minimization of a dimensionless error criterion incorporating various thermodynamic data (saturation pressure, vaporization enthalpy, and liquid density) at ambient conditions and at 350 and 450 K. A comprehensive comparison of the new model is given with other intermolecular potentials taken from the literature.

[Intestinal perforations in percutaneous surgery of the kidney].

Using 9 personal surveys and 11 cases found in the literature, the authors analyse the etiologies of this iatrogenic accident, the often secondary modalities of the diagnosis and the benign nature of the fistula which usually heals spontaneously.

[The Carboclip, a new, atraumatic vascular access for hemodialysis].

The Carboclip is a no-needle vascular access device made of an inverted Titanium body. The horizontal bar of 6 mm inner diameter is connected with artery and vein via a vascular graft. The vertical body houses an elastic plug in which is inserted a double canula diving in the blood stream for extracorporeal blood circulation (EBC).

[Preserved saphenous grafts in hemodialysis. 20 years' experience].

From 1972 to 1992, 790 vascular conduits were implanted as vascular access in hemodialysis patients, of whom 402 were "longs" (length above 15 cm), with 168 PTFE grafts and 234 homosaphenous preserved vein grafts matching 136 manufactured and 98 self-prepared grafts. Functional period of time as 10 years has been obtained with the two materials, and up to twelve years with one manufactured graft. Among complications were observed 12% serious infection with PTFE graft compared to 2% with homosaphenous graft; aneurysm on 9% of PTFE grafts and 11% of saphenous graft, stenosis on vein graft anastomosis in 65% of the PTFE cases and 85% of the saphenous cases.

Expanded polytetrafluoroethylene prostheses as secondary blood access sites for hemodialysis: pathological findings in 29 excised grafts.

The popularity of expanded polytetrafluoroethylene (PTFE) arteriovenous fistulas for hemodialysis access is increasing. The low infection rate, low thrombogenicity and low body reactivity make it an important blood access for patients on routine hemodialysis. The authors examined 29 PTFE graft fistulas surgically excised from patients on hemodialysis for one or more of the following complications: infection 7, 2 with associated hemorrhage; thrombosis 9; aneurysm 11, 3 with associated thrombosis; stenosis 5, 3 with associated thrombosis; hemorrhage 4 and arterial steal 2.

[Stripped veins for secondary vascular access in hemodialysis. Pathologic study of the grafts after surgical excision].

The suitability of stripping vein homografts as AV fistulae for intermittent hemodialysis has been evaluated. Microscopic investigation of stored veins indicated the superiority of cryopreservation over refrigeration. A systematic study of 12 venous homograft fistulae surgically excised from hemodialysis patients revealed that the homograft walls are the sites of both connective tissue proliferation and of mural degeneration.

[Progressive complications associated with the use of a bovine heterograft for vascular access].

Three bovine carotid heterografts, used for vascular access, were analysed after removal following the development of aneurysms in two cases and thrombosis in one. The first prosthesis was implanted in a 17-year-old man who suffered from myasthenia gravis and was undergoing plasmapheresis. It became notably dilated several months after implantation, and resection was necessary 14 months after insertion.

[Results of a serological survey made in France (Vendeé region) in domestic ducks].

The sera of domestic ducks were examined for antibodies to several infectious agents of palmipeds during the winter of 1982 in the abattoirs in la Vendée, an important region of duck production in the West of France. The performance of each batch and their antecedents was also studied. In Barbary ducks and crossbred ducks (from male wild ducks and female domestic ducks), antibodies were found to the virus of egg drop syndrome 16 (EDS 76), to Newcastle disease virus (NDV), to duck hepatitis virus and to chlamydia psittici.

["Suspended" segmental replacement of the ureter using the ileum. Experimental results at five years (author's transl)].

Segmental replacement of the ureter using an intestinal segment has given good long term experimental results. Preservation of the pelvic ureter has two advantages:--The use of a short intestinal loop, which decreases the secretion of mucus, stagnation and electrolyte reabsorption;--preservation of the normal uretero-vesical junction, thereby avoiding reflux. At the beginning of this experimental study, it was feared that the pelvic ureter would become obstructed by mucus and that the insufficiently contractile and atonic ileal loop would dilate, forming a "pool" of stagnant urine.

Renoureteral bypass in obstructions and losses of substance of the initial ureter.

When the renal pelvis and the proximal ureter are destroyed, surgical repair is always difficult. In case of a loss of substance of the upper ureter, it is possible to replace the obstructed (or destroyed) segment and to preserve the healthy iliopelvic ureter. The 'renoureteric bypass' consists of the insertion of an intermediate segment between the lower calyx of the kidney and the lumboiliac ureter.