Theoretical study on the molecular stacking interactions and charge transport properties of triazasumanene crystals - from explanation to prediction.

Computational analyses of the solid-state properties of triazasumanene (TAS), a C3-symmetric nitrogen-doped sumanene derivative, were carried out in this work. The present studies are mainly divided into two parts. In the first part, we demonstrated the differences in the interactions of the crystal packing between the racemic and the homochiral structures: the former having perpendicular columnar packing and the latter forming slipped helical packing. Two geometries of the TAS monomer, a theoretically optimized structure under vacuum and an X-ray crystal structure in experiment, were compared. It can be found that it is not the total interaction energy, but the local interactions (mainly the electrostatic interactions) of the molecular dimer that dominate the columnar stacking conformation. The second part involves the investigation of the potential charge transport properties of the crystals according to the semiclassical Marcus theory with the hopping mechanism using the simple dimer model. The charge transfer integrals of the two sets of dimers, racemic and homochiral dimer models, were compared as well. The calculation results show that the TAS racemic crystal was predicted to have an advantage of hole transport properties. The perpendicular columnar stacking of the homochiral conformation should essentially have better charge transport properties than the racemic conformation. It is reasonable to employ the simple dimer model built using optimized monomers under vacuum for the purpose of the prediction of the molecular packing conformation by IES calculation and the charge transport properties of the perpendicular columnar-stacking crystal. Our work provides a simple approach to the deep understanding of the structure-property relationship of bowl-shaped molecular systems in theory. It can help to facilitate the design and preparation of heteroatom-doped sumanene derivatives with perpendicular columnar stacking crystals as novel organic semiconductor materials.

Reconstruction of auricular conchal defects with local flaps.

Reconstruction of the auricular conchal cavity is relatively difficult because of its unique structure, shape, and location. We compared different methods of repair of the auricular concha to determine the method that would cause the least injury to the donor site.The method selected was based on the location and size of the defect. If the defect was located in the upper part of the concha, or if the defect was >15 mm in diameter, we used a post-auricular subcutaneous pedicle island flap that was pulled through a post-auricular sulcus tunnel to cover the wound. If the defect was located in the lower part of the concha and was <15 mm in diameter, we used a pre-auricular translocation flap that was passed through the intertragic notch to cover the wound. The donor site was closed primarily. All flaps survived well and any scars associated with the surgery were unnoticeable. No tumor relapse or metastasis was observed over a mean follow-up period of 35 months. All patients were satisfied with the outcome.The periauricular flap technique chosen for reconstruction of skin defects in the auricular concha depends on the size and location of the defect. With appropriate flap selection, excellent functional, and aesthetic outcomes are achieved.

An "oxhorn"-shaped V-Y advancement flap unilaterally pedicled on a nasal superficial musculoaponeurotic system for nasal reconstruction.

BACKGROUND: Laterally based nasalis myocutaneous flaps pedicled on the superior nasal superficial musculoaponeurotic system (SMAS), which contains the bilateral dorsal nasal arteries, have not been utilized for the reconstruction of nasal defects. METHODS: According to the location and size of the nasal defects, a V-Y advancement nasalis myocutaneous flap was designed along the proximal alar groove and nasolabial fold. The flap was superficially elevated from the perichondrium, and the nasal SMAS above the flap was dissected as the unilateral pedicle. After the flap was rotated and advanced to the defect, the secondary defect was primarily closed. RESULTS: A total of 20 cases of nasal defects, including six cases of nasal dorsum, five cases of nasal tip, four cases of nasal tip-alar junctions and five cases of nasal tip-dorsum junctions, were reconstructed using this method. The defect size ranged from 0.8 × 0.8 cm to 2 × 1.8 cm. All of the flaps survived with satisfactory aesthetics and function. All of the patients were postoperatively followed up for 6-12 months. CONCLUSION: Application of the V-Y advancement nasalis myocutaneous flaps pedicled on a nasal SMAS is appropriate for the reconstruction of small to medium sized nasal tips and peri-tip defects, and it can achieve satisfactory results due to its simple design, convenient transfer, reliable blood supply and concealed incision.

[In vitro proliferation of rat Leydig cells].

OBJECTIVE: To investigate the feasibility of in vitro proliferation of rat Leydig cells by modifying the cell culture system. METHODS: Leydig cells were isolated from three-week-old rats by a procedure combining collagenase dispersion, stainless steel mesh infiltration and differential adhesion. The isolated cells were cultured in DMEM/F12 and modified media for stem cell proliferation, and the proliferation of the cultured cells was evaluated by cell counting and MTP test. The expression of 3beta-HSD in the cultured cells was detected by immunohistochemistry and flow cytometry, and testosterone productivity in the isolated Leydig cells with or without hCG stimulation was determined at 2 hours and 4 days after cell isolation. RESULTS: The Leydig cells cultured in the modified media proliferated actively, with a doubling time of (2.26 +/- .31) days, as compared with (16.32 +/- 2.14) days for those cultured in the traditional media (P <0.05). The 3beta-HSD positive rate in the cultured cells was (554.3 +/- 7.1)% after 2 hours and (93.6 +/- 4.6)% after 4 days of culture. All the proliferated cells exhibited testosterone productivity, and their testosterone secretion was significantly upregulated by hCG stimulation (P <0.05). CONCLUSION: Leydig cells isolated by differential adhesion proliferate actively in the modified culture media.

[The treatment of lower eyelid retraction at the different degree].

OBJECTIVE: To explore the effective methods for the correction of lower eyelid retraction at different degree. METHODS: 258 patients with lower eyelid retraction were treated in our department since 1999. The lower eyelid retraction could be divided into mild, moderate and severe degree. The lateral canthal anchoring (n = 150), Hamra's lower eyelid blepharoplasty (n = 80) and translid cheek lifting (n = 28) were adopted according to the severity. The therapeutic effect for different degree of lower eyelid retraction was compared. RESULTS: 98 patients were followed up for 3-12 months, including 51 patients of mild degree, 29 patients of moderate degree, and 18 patients of severe degree. The retraction were corrected completely in 91 patients. The lower eyelid was repositioned to the level of inferior limbus without inferior scleral show when eyes opened. The palpebral fissure could close completely. The blunt lateral canthus turned to be acute and the scar was inconspicious. The retraction was improved, but not corrected completely in 3 patients of moderate degree and 4 patients of severe degree. The complications included petechiae, chemosis, and so on. CONCLUSIONS: The lower eyelid retraction can be corrected effectively if the appropriate techniques are performed according to the degree of retraction.