[Retention after orthodontic treatment].

In general, the result of orthodontic treatment is not stable. After active treatment, changes can occur as a result of a number of biological processes. The application of retention aims to counteract such changes and thereby preserve the result of orthodontic treatment.

[Orthodontic retention: problems and problem-solving strategies].

The aim of orthodontic retention is to counteract post-treatment changes and thereby to preserve the result of active treatment. For active orthodontic treatment, a certain level of patient compliance is necessary and the same applies for the retention phase. Ideally, the retainer will never fail or get lost, the patient will adhere to all recommendations and will wear the retainer in accordance with the instructions, necessary precautions with the fixed retainer are followed, the patient reports a problem immediately, and appointments for retention check-ups will always be met.

N-Heterocyclic Carbenes Reduce and Functionalize Copper Oxide Surfaces in One Pot.

Benzimidazolium hydrogen carbonate salts have been shown to act as N-heterocyclic carbene precursors, which can remove oxide from copper oxide surfaces and functionalize the resulting metallic surfaces in a single pot. Both the surfaces and the etching products were fully characterized by spectroscopic methods. Analysis of surfaces before and after NHC treatment by X-ray photoelectron spectroscopy demonstrates the complete removal of copper(II) oxide.

N-heterocyclic carbene-functionalized magic-number gold nanoclusters.

Magic-number gold nanoclusters are atomically precise nanomaterials that have enabled unprecedented insight into structure-property relationships in nanoscience. Thiolates are the most common ligand, binding to the cluster via a staple motif in which only central gold atoms are in the metallic state. The lack of other strongly bound ligands for nanoclusters with different bonding modes has been a significant limitation in the field.

Epidemiologic study of orthodontic retention procedures.

Introduction: The aims of this study were to survey current retention procedures applied by Dutch orthodontists and to examine their acquaintance with "unintentionally active retainers."

Methods: A questionnaire was sent to all 306 Dutch orthodontists involved in patient treatment. Questions were clustered in 4 parts: (1) general information, (2) retention procedures, (3) characteristics of wire materials for bonded retainers, and (4) acquaintance with "unintentionally active retainers.

N-Heterocyclic Carbene Self-Assembled Monolayers on Gold as Surface Plasmon Resonance Biosensors.

Surface plasmon resonance (SPR)-based biosensing is a powerful tool to study the recognition processes between biomolecules in real-time without need for labels. The use of thiol chemistry is a critical component in surface functionalization of various SPR biosensor surfaces on gold. However, its use is hampered by the high propensity for oxidation of the gold-thiol linkage even in ambient atmosphere, resulting in a short lifetime of SPR sensor chips unless strict precautions are taken.

Characterizing Substrate-Surface Interactions on Alumina-Supported Metal Catalysts by Dynamic Nuclear Polarization-Enhanced Double-Resonance NMR Spectroscopy.

The characterization of nanometer-scale interactions between carbon-containing substrates and alumina surfaces is of paramount importance to industrial and academic catalysis applications, but it is also very challenging. Here, we demonstrate that dynamic nuclear polarization surface-enhanced NMR spectroscopy (DNP SENS) allows the unambiguous description of the coordination geometries and conformations of the substrates at the alumina surface through high-resolution measurements of C-Al distances. We apply this new technique to elucidate the molecular-level geometry of C-enriched methionine and natural abundance poly(vinyl alcohol) adsorbed on γ-AlO-supported Pd catalysts, and we support these results with element-specific X-ray absorption near-edge measurements.

[Gingival recessions and periodontal plastic surgery].

Periodontal plastic surgery is defined as the set of surgical procedures that are performed to prevent or correct developmental disorders and anatomical, traumatic and pathological abnormalities of the gingiva, alveolar mucosa, and alveolar bone. Root coverage procedures fall under this term and have been applied for more than fifty years with varying degrees of success. There are several indications for the treatment of gingival recessions.

[Gingival recessions and orthodontics].

Gingival recessions represent the most visible periodontal disease. The prevalence of gingival recessions is high. The root surface is literally exposed to negative influences such as erosion, abrasion, discoloration and decay.

Impact of protecting ligands on surface structure and antibacterial activity of silver nanoparticles.

Silver nanoparticles (Ag NPs) have attracted much attention in the past decade because of their unique physicochemical properties and notable antibacterial activities. In particular, thiol-protected Ag NPs have come to the forefront of metal nanoparticle studies, as they have been shown to possess high stability and interesting structure-property relationships. However, a clear correlation between thiol-protecting ligands, the resulting Ag NP surface structure, and their antibacterial properties has yet to be determined.

Hepatic steatosis assessment with CT or MRI in patients with colorectal liver metastases after neoadjuvant chemotherapy.

Purpose: Preoperative radiological assessment of hepatic steatosis is recommended in patients undergoing a liver resection, but few studies investigated the diagnostic accuracy after neoadjuvant chemotherapy. The aim of this study was to compare diagnostic accuracy of preoperative CT or MRI measurements of steatosis in patients with colorectal liver metastases after induction chemotherapy.

Methods: MRI measurements (relative signal intensity decrease; RSID), N = 36, and CT scan measurements (Hounsfield units; HU), N = 32, were compared with histological steatosis assessment.

Gold nanoparticles on titanium and interaction with prototype protein.

Modifying titanium (Ti) implant surfaces with functional proteins can strengthen the interface between prosthesis and bone. A prototype system was developed using gold nanoparticles (AuNPs) to immobilize proteins onto Ti. An electroless (galvanic displacement) deposition method was first used to form AuNPs of controlled size and coverage on commercial Ti foil (giving Ti-AuNPs).

Structural and electronic properties of protein/thiolate-protected gold nanocluster with "staple" motif: A XAS, L-DOS, and XPS study.

Following the recent breakthrough of total structural determination of a Au-thiolate nanocluster [P. Jadzinsky et al., Science 318, 430 (2007)], extensive interests have been stimulated to unveil (or revisit) the structure-property relationship of various thiolate-Au nanostructures in light of the new finding of -SR-(Au-SR)(x)- "staple" motif.

Surface structural characteristics and tunable electronic properties of wet-chemically prepared Pd nanoparticles.

The ligand substitution reaction, Pd L(3,2,1)-edge and S K-edge x-ray absorption fine structure (XAFS), XAFS simulations, and valence-band and core-level x-ray photoelectron spectroscopy (XPS) have been used to systematically study the surface chemical and electronic properties of wet-chemically prepared Pd nanoparticles of varied size, molecular capping, and metal composition. It was found that the replacement of weakly interacting capping molecules (amine and tetra-alkylphosphonium bromide) with strongly binding thiols caused a considerable change in the surface bonding of Pd nanoparticles. However, the Pd d-electron counts (number of d electrons) remained almost unchanged before and after ligand substitution, which is unexpected since Pd atoms normally lose electrons to the more electronegative S atoms.