Biomedical subjects

Jianmin Shi

Publications and source records attributed to Jianmin Shi.

6 recordsLinked to original sources

PubMed2005

Photophysical properties of anthanthrene-based tunable blue emitters.

Anthanthrene (1) derivatives substituted at the 4,10 and 6,12 positions (2-6) were synthesized as promising candidates for organic light emitting diodes (OLEDs). The emission of these compounds can be manipulated in the blue region (lambda(max) = 437-467 nm) through structural modifications. Photophysical and electrochemical properties (phi(F) = 0.20-0.47; tau(F) = 2.97-6.06 ns; HOMO-LUMO energy gap = 2.25-2.56 eV) as well as geometry optimized structures of 1-6 are reported.

Journal Article↗

PubMed2005

Photophysical and electrochemical properties of heteroleptic tris-cyclometalated iridium(III) complexes.

Mixed (difluoro)phenylpyridine/(difluoro)phenylpyrazole tris-cyclometalated iridium complexes were prepared in order to study the effect of fluorination and the pyridine/pyrazole ratio on the emission and electrochemical properties. Increasing fluorination and replacement of pyridine by pyrazole both leads to a widening of the HOMO-LUMO gap and generally leads to a blue shift in emission.

Journal Article↗

PubMed2004

Effect of time on bond strength in indirect bonding.

The purpose of this in vitro investigation was to determine the influence of a reduced time interval before debonding on shear bond strength of stainless steel brackets bonded with a custom base indirect technique. A total of 135 bovine permanent mandibular incisors was randomly divided into nine groups of 15 specimens each. Three base composite-sealant combinations were investigated: (1) Phase II base composite, Custom I.Q. sealant, (2) Phase II base composite, Maximum Cure sealant, and (3) Transbond XT base composite, Sondhi Rapid Set sealant. Shear bond strength was measured for three different debonding time intervals: (1) time of transfer tray removal as recommended by the manufacturer, (2) 30 minutes after bonding of the sealant, and (3) 24 hours after bonding of the sealant. For groups bonded with Maximum Cure or Sondhi Rapid Set sealants, no influence of debonding time on shear bond strength was found. The Custom I.Q. sealant groups showed significantly lower bond strength measurements when debonded at the recommended tray removal time, and the Weibull analysis indicated a higher risk of bond failure at clinically relevant levels of stress. All base composite-sealant combinations showed acceptable bond strength at 30 minutes and 24 hours after bonding of the sealant.

Analysis of Variance↗

PubMed2003

In vitro investigation of indirect bonding with a hydrophilic primer.

The aim of this in vitro investigation was to evaluate bond strength for a custom base indirect bonding technique using a hydrophilic primer on moisture-contaminated tooth surfaces. Stainless steel brackets were bonded to 100 permanent bovine incisors using a light-cured custom base composite adhesive, a chemically cured sealant, and the hydrophilic primer Transbond MIP (3M-Unitek, Monrovia, Calif). Five groups (A-E) of 20 teeth each were formed according to the time of contamination (before or after application of the primer) and the type of contaminant (distilled water or saliva): A, control group with no contamination; B, contamination with saliva before application of the primer; C, contamination with water before application of the primer; D, contamination with saliva before and after application of the primer; and E, contamination with water before and after application of the primer. Mean bond strength for the group without contamination (A) was 15.07 +/- 4.14 MPa and was not significantly different from bond strengths for groups B (14.91 +/- 3.99 MPa) and C (16.12 +/- 3.67 MPa), in which contamination occurred before application of the hydrophilic primer. Average bond strength in group D was 11.92 +/- 4.76 MPa. The lowest mean bond strength was measured for group E (9.85 +/- 3.77 MPa) and was significantly lower than for groups A, B, and C. Contamination after primer application resulted in an increased risk of bond failure at clinically relevant levels of stress.

Adhesives↗

PubMed2003

In vitro evaluation of a moisture-active adhesive for indirect bonding.

The aim of this in vitro investigation was to evaluate bond strength for a cyanoacrylate adhesive in combination with an indirect bonding technique. Eighty bovine permanent mandibular incisors were randomly divided into four groups of 20 teeth each. The influence of two factors on shear bond strength was investigated: (1) type of adhesive (Smartbond cyanoacrylate, Sondhi Rapid Set composite sealant) and (2) time of debonding (30 minutes and 24 hours after bonding). Stainless steel mesh-based brackets were used. Although, bond strength was not significantly different for the two debonding time periods, significantly lower bond strength measurements were found for the cyanoacrylate adhesive (P < .001). The mean bond strength for the cyanoacrylate adhesive group was 5.44 +/- 1.65 MPa for debonding 30 minutes and 6.92 +/- 1.48 MPa for debonding 24 hours after the bonding procedure vs 16.16 +/- 5.25 MPa and 14.98 +/- 2.85 MPa for the composite adhesive groups debonded at 30 minutes and 24 hours, respectively. The Weibull analysis indicated that there was an increased risk of bond failure at clinically relevant levels of stress for indirect bonding with the cyanoacrylate adhesive.

Adhesives↗

PubMed2003

Bond strength with custom base indirect bonding techniques.

Different types of adhesives for indirect bonding techniques have been introduced recently. But there is limited information regarding bond strength with these new materials. In this in vitro investigation, stainless steel brackets were bonded to 100 permanent bovine incisors using the Thomas technique, the modified Thomas technique, and light-cured direct bonding for a control group. The following five groups of 20 teeth each were formed: (1) modified Thomas technique with thermally cured base composite (Therma Cure) and chemically cured sealant (Maximum Cure), (2) Thomas technique with thermally cured base composite (Therma Cure) and chemically cured sealant (Custom I Q), (3) Thomas technique with light-cured base composite (Transbond XT) and chemically cured sealant (Sondhi Rapid Set), (4) modified Thomas technique with chemically cured base adhesive (Phase II) and chemically cured sealant (Maximum Cure), and (5) control group directly bonded with light-cured adhesive (Transbond XT). Mean bond strengths in groups 3, 4, and 5 were 14.99 +/- 2.85, 15.41 +/- 3.21, and 13.88 +/- 2.33 MPa, respectively, and these groups were not significantly different from each other. Groups 1 (mean bond strength 7.28 +/- 4.88 MPa) and 2 (mean bond strength 7.07 +/- 4.11 MPa) showed significantly lower bond strengths than groups 3, 4, and 5 and a higher probability of bond failure. Both the original (group 2) and the modified (group 1) Thomas technique were able to achieve bond strengths comparable to the light-cured direct bonded control group.

Acrylic Resins↗