Search results for "engineering.material"
showing 10 items of 2352 documents
Ecotoxicity of halloysite nanotube-supported palladium nanoparticles inRaphanus sativusL
2016
Halloysite nanotubes (HNTs) are natural nanomaterials that are biocompatible and available in large amounts at low prices. They are emerging nanomaterials with appealing properties for applications like support for metal nanoparticles (NPs). The potential environmental impacts of NPs can be understood in terms of phytotoxicity. Current research has been focusing on HNT applications in cell or animal models, while their use in plants is limited so their ecotoxicological impact is poorly documented. To date there are no studies on the phytotoxic effects of functionalized halloysites (functionalized-HNTs). To develop a quantitative risk assessment model for predicting the potential impact of H…
Telechelic Star Polymers as Self-Assembling Units from the Molecular to the Macroscopic Scale
2012
By means of multiscale molecular simulations, we show that telechelic-star polymers are a simple, robust, and tunable system, which hierarchically self-assembles into soft-patchy particles and mechanically stabilizes selected, open crystalline structures. The self-aggregating patchy behavior can be fully controlled by the number of arms per star and by the fraction of attractive monomeric units at the free ends of the arms. Such self-assembled soft-patchy particles while forming, upon augmenting density, gel-like percolating networks, preserve properties as particle size, number, and arrangement of patches per particle. In particular, we demonstrate that the flexibility inherent in the soft…
Magneto-optical nanomaterials: a SPIO–phthalocyanine scaffold built step-by-step towards bimodal imaging
2013
A SPIO-phthalocyanine nanohybrid is developed as a bimodal contrast agent for Optical and Magnetic Resonance Imaging. The organic coating was covalently attached onto SPIO in a step-by-step approach. Each coated-SPIO was thoroughly characterized. The hydrodynamic size of the SPIO-Pc is ca. 60 nm with a coverage of ca. 690 Pc/SPIO.
Elastic torsion effects in magnetic nanoparticle diblock-copolymer structures
2011
Magnetic properties of thin composite films, consisting of non-interacting polystyrene-coated γ-Fe(2)O(3) (maghemite) nanoparticles embedded into polystyrene-block-polyisoprene P(S-b-I) diblock-copolymer films are investigated. Different particle concentrations, ranging from 0.7 to 43 wt%, have been used. The magnetization measured as a function of external field and temperature shows typical features of anisotropic superparamagnets including a hysteresis at low temperatures and blocking phenomena. However, the data cannot be reconciled with the unmodified Stoner-Wohlfarth-Néel theory. Applying an appropriate generalization we find evidence for either an elastic torque being exerted on the …
Water barrier properties of treated-papers and application to sponge cake storage
2006
Abstract Water barrier properties of three treated papers and of one plastic film were compared and the potential of these packaging films to prevent moisture loss from a sponge cake during storage in standard conditions (25 °C and 50% relative humidity gradient) was evaluated. Sorption isotherms were established at 25 °C for both sponge cake and papers, from which diffusivity values in papers were determined for the whole range of A w . Permeability of packaging films was determined in standard conditions. Water sorption was close for all papers, regardless of their treatment, whereas water diffusivity was reduced by coating or calendering. Water vapor permeability in papers was controlled…
Solubility of the assemblage albite+K-feldspar+andalusite+quartz in supercritical aqueous chloride solutions at 650 °C and 2 kbar
2003
Abstract The solubility of the high grade pelite assemblage albite+K-feldspar+andalusite+quartz at 650 °C and 2 kbar was determined in aqueous solutions over a total chloride range of 0.01–3 mCltot using rapid-quench hydrothermal technique. The concentration of Na, K, Si, and Al was determined in the fluid phase after quench. The K/Na ratio was determined by approaching the equilibrium from below and above. It is 0.34 at low chloride concentrations and decreases slightly to 0.31 with increasing total chloride. Silica and aluminum concentrations were determined only from undersaturation. The silica solubility is found to be independent of chloride concentration and is ∼0.13 molal. Aluminum i…
Experimental study on the solubility of the “model”-pelite mineral assemblage albite + K-feldspar + andalusite + quartz in supercritical chloride-ric…
2001
A total of 34 solubility experiments using the “model”-pelite mineral assemblage microcline + low albite + andalusite + quartz were performed at 600°C and 0.2 GPa over a total chloride range of 0.03–2.9 molal. The concentrations of sodium, potassium, aluminum, and silica were measured and the results are compared with four different thermodynamic datasets. The K/Na ratio was approached from below and above for the thermodynamically buffered mineral assemblage microcline + low albite + andalusite + quartz. Tight brackets were obtained for experiments performed in up to 1 molal chloride concentration. From 0.03 to ∼1 molal chloride concentration, a constant K/Na ratio of 0.33 was obtained. At…
Intentional replantation for the management of maxillary sinusitis.
2007
AIM: To present a case that emphasizes the importance of the use of intentional replantation as a technique to successfully treat a periapical lesion and an odontogenic maxillary sinusitis through the alveolus at the same time. SUMMARY: This case report presents a patient with odontogenic maxillary sinusitis secondary to periapical disease of a maxillary molar that had previously received root canal treatment. The molar was extracted, with drainage and rinsing of the maxillary sinus. The apices were resected extra-orally, the retrograde cavities prepared with ultrasound and retrograde fillings of silver amalgam placed. The tooth was then replanted. After 2 years, the patient was asymptomati…
Effect of rotary cutting instruments on the resin-tooth interfacial ultra structure: An in vivo study
2013
Objectives: To evaluate the effect of cutting teeth with different types of burs at various speeds on surface topogra - phy of tooth surface and interfacial gap formation at resin-tooth interface. Material and Methods: The human molars were divided into seven groups: Diamond bur in airrotor (DA) & mi - cromotor (DM), crosscut carbide bur in airrotor (CCA) & micromotor (CCM), plain carbide bur in airrotor (CA) & micromotor (CM) and #600-grit silicon carbide paper (SiC). In five samples from each group Class II box-only cavities were restored. The occlusal surface of four teeth per group was flattened. Two out of four teeth were acid etched. Teeth were subjected for scanning electron microsco…
In-vitro-Studie der Interferenz von kieferorthopädischer Bebänderung und Füllungswerkstoffen
1992
Discoloring and layers on bands and restorations during fixed orthodontic therapy are well known clinical phenomenon. Because of the complexity of etiological factors an in-vitro model was used in this study. Aim of the study was to examine the amounts and sort of metals which are dissolved. Therefore, respectively 25 normed MOD-cavities in Frasaco-teeth were filled with a non-gamma-2-amalgam (Amalcap plus, Vivadent) and condensed manually or mechanically. In addition, ten crowns of a high golden (Maingold SG, Heraeus) as well as a palladium basis alloy (Albabond A, Heraeus) were casted. Then they were banded with stainless steel bands (Dentaurum) and cemented with a glass ionomer cement (K…