Parallel-stacked aromatic molecules in hydrogen-bonded inorganic frameworks.

By precisely constructing molecules and assembling these into well-defined supramolecular structures, novel physical properties and functionalities can be realized, and new areas of the chemical space can be accessed. In both materials science and biology, a deeper understanding of the properties and exploitation of the reversible character of weak bonds and interactions, such as hydrogen bonds and π-π interactions, is anticipated to lead to the development of materials with novel properties and functionalities. We apply the hydrogen-bonded organic frameworks (HOFs) strategy to inorganic materials science using the cubic octamer of orthosilicic acid, [SiO][OH], as a building block, and find that various types of hydrogen-bonded inorganic frameworks (HIFs).

Treating octasilanol [SiO][OH] with tetramethoxysilane and trimethoxyvinylsilane: a halogen-free synthetic route to alkoxysilyl-substituted double-four-ring siloxanes.

The synthesis of methoxysilyl-substituted siloxanes with a double-four-ring (D4R) framework [Si8O12][OSiR(OMe)2]8 (R = OMe or vinyl) via the dealcoholative coupling between silanol [Si8O12][OH]8 and alkoxysilane was accomplished and achieved a halogen-free synthetic process. The solid-state structure of [Si8O12][OSi(OMe)3]8 was determined via a single-crystal X-ray diffraction analysis.

A catalyst- and additive-free synthesis of alkoxyhydrosiloxanes from silanols and alkoxyhydrosilanes.

A convenient method for the selective synthesis of alkoxyhydrosiloxanes that bear SiH and SiOR groups on the same silicon atom, RSi-O-SiR(OR)H (n = 0, 1, or 2), via a simple catalyst- and additive-free dealcoholization reaction between silanols and alkoxyhydrosilanes has been developed. These alkoxyhydrosiloxanes can be easily converted into Si(OR)-containing siloxanes by zinc catalyzed alkoxylation and alkoxy-containing silphenylene polymers by platinum catalyzed hydrosilylation.

Methanol extract of mycelia from Phytophthora infestans-induced resistance in potato.

Plants recognize certain microbial compounds as elicitors in their active defence mechanisms. It has been shown that a series of defence reactions are induced in potato plant cells after treatment with water-soluble hyphal wall components prepared from Phytophthora infestans. In this study, a methanol extract from mycelia of P.

A three-die cast technique for duplicating free gingival form in zirconia crowns: two case reports.

This report describes a duplication technique of free gingival form from a provisional restoration to a zirconia crown. Three die casts were manufactured from a silicone impression with an acrylic resin ring tray. The first die cast was for the zirconia framework, the second for the provisionalized transfer coping, and the third for relining the provisional restoration.

Intentional Gingival Retraction With Provisional Direct Restoration: A Novel Approach to Facial Crown Lengthening.

Introduction: Achieving a harmonious marginal gingiva is an important factor in esthetic dentistry. However, surgical crown lengthening of single teeth risks asymmetry of the gingival outline in the esthetic zone. In restorative dentistry, excessive gingival retraction or deep subgingival preparation can cause facial gingival recession.

Isolable p- and m-[((t)Bu2MeSi)2Si]2C6H4: disilaquinodimethane vs triplet bis(silyl radical).

Isomeric p- and m-disilaquinodimethanes 2 and 4 were synthesized by the reductive dehalogenation of the corresponding p- and m-bis(halosilyl)benzenes 1 and 3, respectively, and were isolated and structurally characterized. The X-ray diffraction and solid-state NMR studies of 2 revealed its singlet quinodimethane structure featuring two exocyclic Si═C double bonds with some singlet biradical contribution. In contrast, the X-ray crystallography and EPR measurements of 4 disclosed its biradical nature, described as a triplet ground state bis(silyl radical).

The distances between the facial and palatal papillae in the maxillary anterior dentition.

This study examined the distances between the facial and palatal papillae (DFPP) in the maxillary anterior dentition. A total of 360 filled interdental papillae in 72 study models were examined (Group A: 36 young patients, Group B: 36 adult patients). The DFPP was measured directly on alginate impressions.

A free gingival impression for achieving optimal interdental papilla height: a case report.

Failure to tend to inadequate crown contours in the crown trial can cause long-term disharmony of the free gingival form. This case report describes a novel technique for free gingival impression from a final provisional restoration to a zirconia crown. Two die casts were manufactured from a silicone impression.

The concept of the interdental gingival midpoint line in cervical line management.

The first purpose of this study was to investigate the relationship between the lowest cervical point and the interdental gingival midpoint (IGM) line in the maxillary anterior region. After marking the lowest cervical points and the mesial and distal interdental gingival midpoints on study models of 77 patients, the shortest distances from the IGM lines that connect both interdental gingival midpoints to the lowest cervical points were measured on silicone impressions. The findings showed that the average position of the lowest cervical points in the central incisors coincides with the IGM line.

Biologic height-width ratio of the buccal supra-implant mucosa.

Recently, esthetic implant dentistry has focused on changes in buccal implant mucosal height. The purpose of this article was to investigate the relationship between the height and width of buccal supra-implant mucosa based on the physiologic mucosal form surrounding the implant. Fourteen patients who had buccal supra-implant mucosal heights of more than 1.

Buccal and coronal bone augmentation using forced eruption and buccal root torque: a case report.

The following case report describes the buccal and coronal bone augmentation around an irretrievable tooth using forced eruption and buccal root torque for immediate nonsubmerged implant placement. A mandibular left second premolar with degree 2 mobility, severe buccal bone resorption, and interproximal angular bony defects was subjected to forced eruption and buccal root torque. Five months after this process, the tooth was displaced 15 mm coronally and the root apex faced buccally.

Connective tissue-bone onlay graft with enamel matrix derivative for treatment of gingival recession: a case report.

We describe a case of gingival recession in which root coverage and coronal bone regrowth were achieved after treatment with a connective tissue-bone graft and enamel matrix derivative. The connective tissue-bone graft was harvested from a maxillary edentulous area and then curved to fit the root surfaces of the maxillary left central and lateral incisors. Enamel matrix derivative was applied to the root surfaces, and the connective tissue-bone graft was fixed to the interdental bone by a titanium screw.