Synthesis and carbothermal nitridation mechanism of ultra-long single crystal α-Si3N4 nanobelts.

One-dimensional Si3N4 nanostructures are desirable for constructing nanoscale electric and optoelectronic devices due to their peculiar morphologies. Herein, a facile and environmentally friendly catalyst-free method is proposed to synthesize ultra-long single crystal α-Si3N4 nanobelts via carbothermal nitridation of carbon nanotubes at 1750 °C. The obtained α-Si3N4 nanobelts with a flat surface (thickness of ∼150 nm, length of several millimeters) exhibited an extremely high aspect ratio, perfect crystal structure, and high specific surface area of 7.34-10.09 m2 g-1. In addition, the width was increased from approximately 80 nm to 8 µm by increasing the holding time from 1 to 3 h. The nanobelt formation was governed by the vapor-solid (VS) reaction between SiO vapor, N2 and carbon nanotubes, and the vapor-vapor reaction between SiO, CO and N2. The former was responsible for the initial nucleation and successive base-growth of α-Si3N4 nanotubes. The latter additionally contributed to the nanorod and subsequent proto-nanobelt formation and to the growth of the nanobelts. During high-temperature annealing at 1750 °C, the original Si3N4 nanotubes gradually transformed into nanorods, and, finally, nanobelts with stable shapes as a result of surface energy minimization.

Development of an Immunoassay for Chloramphenicol Based on the Preparation of a Specific Single-Chain Variable Fragment Antibody.

Specific antibodies are essential for the immune detection of small molecule contaminants. In the present study, the heavy and light variable regions (V(H )and V(L)) of the immunoglobulin genes from a hybridoma secreting a chloramphenicol (CAP)-specific monoclonal antibody (mAb) were cloned and sequenced. In addition, the light and heavy chains obtained from the monoclonal antibody were separated using SDS-PAGE and analyzed using Orbitrap mass spectrometry. The results of DNA sequencing and mass spectrometry analysis were compared, and the V(H) and V(L) chains specific for CAP were determined and used to construct a single-chain variable fragment (scFv). This fragment was recombinantly expressed as a soluble scFv-alkaline phosphatase fusion protein and used to develop a direct competitive ELISA. Compared with the parent mAb, scFv exhibits lower sensitivity but better food matrix resistance. This work highlights the application of engineered antibodies for CAP detection.

Surgical treatment of popliteal cyst: a systematic review and meta-analysis.

BACKGROUND: This systematic review and meta-analysis of the clinical efficacy of different surgical methods in the therapy of popliteal cysts may provide evidence about effective surgical treatments. METHODS: PubMed, EMBASE, and OVID were searched with the following terms: (popliteal cyst* OR baker's cyst*) AND (arthroscopic OR excision OR operative OR treat* OR surgery). Inclusion criteria included the following: studies reported the efficacy of different surgical methods in popliteal cyst patients; patients were ≥ 16 years; and studies must have involved a minimum of 10 patients. Studies were grouped according to the surgical methods, and a meta-analysis was employed to identify the success rate based on the pooled data. RESULTS: A total of 11 studies were included: The communication between the cyst and the articular cavity was enlarged in 7 studies; this communication was closed in 3 studies; and only intra-articular lesions were managed in 1 study. After the data were pooled, the success rates were 96.7 and 84.6 % in the communication-enlargement group and communication-closure group, respectively. Studies with communication enlargement were subgrouped into the cyst wall resection group and the non-cyst wall resection group, for which the success rates were 98.2 and 94.7 %, respectively. CONCLUSIONS: Based on the current available evidence, at present, any how arthroscopic excision of the cyst wall, arthroscopic management of intra-articular lesions, and enlarging the communication between the cyst and the articular cavity is an ideal strategy for the popliteal cyst. The current literature on the treatment of popliteal cysts is limited to retrospective case series. Future prospective studies with high-quality methodology and uniform scoring system are required to directly compare communication-enlargement surgery and communication-closure surgery and determine the optimal treatment of popliteal cysts. Cyst wall resection may improve the therapeutic efficacy, to draw definitive conclusions, and high-level clinical researches with a large number of patients and long-term follow-up should be initiated.

[Treatment of enophthalmos after severe malar-maxillary complex fracture with titanium mesh and high density polyethylene (Medpor)].

OBJECTIVE: To study the surgical management of enophthalmos after severe malar maxillary complex fracture. METHODS: The X-ray and CT examination were performed before operation to diagnose the orbital fracture and intraorbital tissue displacement. The fractured orbital rim was repositioned intraoperatively, followed by implantation of shaped titanium mesh to rebuild the orbital floor. The Medpor was inserted above the titanium mesh to correct the enophthalmos. RESULTS: From Sept. 2007 to Jan. 2009, 6 cases of enophthalmos after severe malar-maxillary complex fracture were treated. The enophthalmos was corrected or improved obviously in all the patients. CONCLUSIONS: The enophthalmos after severe malar-maxillary complex fracture can be corrected or obviously improved. Shaped titanium mesh can be used to rebuild the orbital floor with the Medpor to reconstruct the intraorbital tissue volume.

[Clinical research of angle-splitting ostectomy based on three dimensional computed tomography true-up technique].

OBJECTIVE: To illustrate the morphological changes of mandible after angle-splitting ostectomy. METHODS: From January 2006 to April 2008, 10 cases had undergone mandibular angle-splitting ostectomy to reduce the width of the lower face. For each patient, CT datum of mandible at three stages (preoperative, immediate postoperative, 6 months postoperative) were collected. By the application software of reverse engineering (Surfacer V9) and true-up and dissection techniques based on three-dimensional spiral computed tomography (3D-CT), operative efficacy and bone regeneration at the operation area of angle-splitting ostectomy were evaluated 6 months postoperative. RESULTS: 1) Concavity could be seen at the angle-splitting ostectomy area 6 months postoperative, especially at the mandibular external oblique line region. Average cup depth was (3.64 +/- 1.67) mm by contrasted to preoperative. Diminution of bone volume was 55% +/- 9% for the local operative area 6 months postoperative. 2) Bone regeneration could be seen at the area that mandibular outer cortex had been removed. Compared with immediate postoperative, ratio of neoformative bone was 84.6% +/- 7.3% 6 months postoperative. The main region of bone regeneration was mandibular angle. CONCLUSION: Mandibular angle-splitting ostectomy is an effective technique for reducing the width of the lower face. Masseter muscular movement should be restricted postoperative to prevent hyperostosis at the angle area.

[Comparative study of onlay bone graft absorption of outer cortex from mandible and cranium].

OBJECTIVE: To investigate the value of application of mandibular outer cortex as bone graft by comparing its bone absorption with cranial outer cortex. METHODS: 8 minitype grown-up pigs at the age of 8 - 12 months underwent surgery of taking out the same size (2.5 cm x 1.0 cm) of outer cortex from mandible and craninium. The volume of the outer cortex was measured by volume-displacement method. Then the outer cortex of mandible and cranium were onlay grafted to the each side of the pig snout, respectively. 12 weeks later, 2 pigs were randomly selected for histological examination. The other 6 pigs were killed 24 weeks after surgery for measurement of the bone graft volume and histologic examination. RESULTS: The bone graft absorption rate was (41 +/- 5)% for mandibular outer cortex and (46 +/- 12)% for cranial outer cortex, showing no significant difference between them (P = 0.51). The histologic examination results also had no marked difference in the bony healing and reforming between the two graft. CONCLUSIONS: Mandibular outer cortex is a good donor site for onlay bone graft in craniofacial region.

[Experimental study about osteotomy of mandibular outer cortex].

OBJECTIVE: To investigate the change of morphology, biomechanics and histology after osteotomy of mandibular outer cortex. METHODS: The mandibular outer cortex that involves angle and part of body was removed at one side in 8 minitype pigs aged 8-12 months. 2 pigs were selected randomly for histologic examination 12 weeks after operation. The other 6 animals were killed 24 weeks after operation. The thickness of new-formed mandibular outer cortex was measured and compared with that of operated side. Biomechanical test was performed in bilateral angles. Histological observation was made in the operated side. RESULTS: The thickness of outer cortex was (2.1 +/- 0.3) mm and (2.5 +/- 0.4) mm in the operated side and opposite side, respectively, showing a significant difference between them (P < 0.01). The maximum load was (401.76 +/- 204.91) N and (585.42 +/- 413.07) N in the operated side and opposite side, respectively (P > 0.05). The Rigidity was (2172.19 +/- 1174.73) N/mm and (2363.90 +/- 1547.48) N/mm (P > 0.05). There was no statistical difference in biomechanics between the two sides. The histologic study showed histologically complete regeneration of outer cortex 24 weeks after mandibular outer cortex osteotomy. CONCLUSIONS: After resection of mandibular outer cortex, the histologic restoration is complete, but the new-formed outer cortex is thinner with local depression. Bone tubercle can be seen at the angle after bone regeneration. There is no obvious change in biomechanics after outer cortex osteotomy.

[Clinical research of craniofacial bone autograft using mandibular outer cortex].

OBJECTIVE: To illustrate the volume changes of mandibular outer cortex after been grafted to different recipient sites of facies cranii. METHODS: Six cases underwent onlay bone graft to the angle and body part of mandible and malar surface simultaneously by using mandibular outer cortex. Three dimensional computed tomography (3D-CT) datum of immediate postoperative and 6 months postoperative of each case were collected systematically. By true-up and dissection techniques based on 3D-CT, volume changes of bone graft at different recipient sites were observed and analyzed 6 months postoperative. RESULTS: 6 months after onlay bone grafted, bone resorption occurred. To different recipient sites, bone resorption rate was unequal. At the mandible area, bone resorption rate was 20.8% +/- 7.2%, the main site of resorption was at the lower and posterior border of mandible. At the anterior part of maxilla, bone resorption rate was 11.2% +/- 2.3%. Statistics showed significant difference of resorption rate between the two sites (P<0.05). CONCLUSION: Bone resorption of mandibular outer cortex after onlay graft treatment is variant according to different craniofacial recipient sites. The difference of mechanical environment at variant recipient sites is considered to be an influencing factor. Quantization of bone resorption rate can guide a better clinical use.