Eliminating common biases in modelling the electrical conductivity of carbon nanotube-polymer nanocomposites.

Modelling carbon nanotube-polymer nanocomposites to predict their electrical conductivity demands high computational power. Past research has led to the assumption that conductive networks follow a periodic pattern; however, the impact of the underlying biases had never been investigated. This work provides insights into evaluating such biases and eliminating them to improve simulation accuracy.

Microanatomic study of the vascular and duct system of the submandibular gland.

PURPOSE: Autologous microvascular submandibular gland (SMG) transfer is an effective treatment for severe keratoconjunctivitis sicca (KCS). However, epiphora (excessive tear secretion) may occur after the successful transfer of whole submandibular gland because tear secretion level is closely related to the size of the transferred gland. The aim of this study was to investigate the microanatomy of SMG to explore the possibility of partial SMG transfer to prevent postoperative epiphora. MATERIALS AND METHODS: Sixty intact and histologically normal human SMGs from patients with benign tumor of the mandible who underwent vascularized mandibular reconstruction and removal of the SMG for anastomosis of the blood vessels were included in the study. SMGs were perfused with methacrylate to form resin casts of blood vessels and ducts. The length and diameter of the blood vessels and ducts in the casts were measured using a sliding caliper. The numbers of lobules, distribution of arteries, veins, and ducts, as well as the relationship among them, were analyzed. RESULTS: The resin cast of the gland showed a treelike structure, with the vessels gradually dividing into multiple branches. The arteries, veins, and ducts run in parallel and were roughly divided into 3 levels: from the stem extending into the main branches (level I), into the narrower secondary branches (level II), and then the secondary branches subsequently divided into terminal branches (level III). The structures of the blood vessels and ducts were similar at each level in the lobules. In the vein casts, communicating vessels were found between the anterior facial vein and the concomitant vein of the facial artery. CONCLUSION: The characteristic treelike structure of the SMG vascular and ductal system may provide useful information for partial gland transfers.

Clinical and anatomic study on the ducts of the submandibular and sublingual glands.

PURPOSE: To investigate the relationship between the ducts of the submandibular gland (SMG) and sublingual gland (SLG) and discuss its clinical application relating to SMG radiologic examinations and transfer. MATERIALS AND METHODS: The microanatomy of the SMG and SLG was investigated by use of 30 adult cadavers through anatomic dissection by use of a microscope. The relationship between the SMG and SLG ducts was observed and recorded during operations of microvascular autologous SMG transfer in 63 cases of severe keratoconjunctivitis sicca. RESULTS: There were 3 patterns of SLG and SMG duct anatomic variation: 1) The SMG and SLG have their own respective ducts that secrete separately at the orifices of the ducts in the floor of the mouth. 2) The SLG has a major duct that joins the duct of the SMG. 3) The SLG only has many fine ducts (7-15) that secrete in the floor of the mouth. CONCLUSIONS: The anatomy of the ducts of the SMG and SLG is quite complicated. More attention should be paid to the anatomy of the ducts during surgery or imaging procedures related to the SMG.

Application of 99mTc-pertechnetate scintigraphy to microvascular autologous transplantation of the submandibular gland in patients with severe keratoconjunctivitis sicca.

UNLABELLED: Our objective was to evaluate the role of (99m)Tc-pertechnetate scintigraphy on microvascular autologous transplantation of the submandibular gland in patients with severe keratoconjunctivitis sicca (KCS). METHODS: (99m)Tc-Pertechnetate scintigraphy was performed on 106 patients with severe KCS. The patients were examined before surgery and at 1 wk and 3 mo afterward using a standardized protocol that included static scintigrams, time-activity curves, and delayed scintigrams to check the function and secretion of the major salivary glands. The scintigraphic findings were assessed visually. When possible, the scintigraphic findings were compared with the clinical appearance of the transplanted gland. RESULTS: The function of all 4 major salivary glands was almost completely lost in 10 patients, indicating that these patients were not suitable for transplantation. The other 96 patients were treated by autologous transplantation of the submandibular gland. In 14 patients, the function of the major salivary glands was below normal. One patient's scintigram, obtained on the second day after surgery, showed no uptake of (99m)Tc-pertechnetate in the transplanted gland. Surgical exploration showed embolism of the artery of the transplanted gland. Scintigraphy was performed 1 wk after surgery in 90 patients. There was no uptake of (99m)Tc-pertechnetate in the temporal region in 8 patients, indicating that the glands were not revascularized. Scintigraphy showed obvious uptake of (99m)Tc-pertechnetate in the temporal region of the other 82 patients, indicating that the transplanted glands were viable. At more than 3 mo after surgery, scintigraphy was again performed on 30 patients. Scintigraphy after a 120-min delay showed that (99m)Tc-pertechnetate drained into the orbit through the duct of the transplanted gland in 26 patients. However, no secretion into the orbit was found in 4 patients, indicating obstruction of the duct. CONCLUSION: Scintigraphy plays an important role in microvascular autologous transplantation of the submandibular gland in patients with severe KCS. Scintigraphy can be used to select patients and donor glands, to evaluate the viability of the graft, and to check the patency of Wharton's duct of the transplanted gland.

Anatomy of arteries and veins of submandibular glands.

BACKGROUND: Transplanting a vascularized autologous submandibular gland (SMG) is considered an effective method to treat severe keratoconjunctivitis sicca. But the operation may fail due to the anatomic variances in the blood vessels of SMG. The present study aimed to investigate the submandibular glands at the microanatomy level. METHODS: The microanatomy of blood vessels including arteries and veins of submandibular gland was investigated using 30 adult corpses and 60 submandibular glands were anatomized under a surgical microscope. The lengths and diameters of the arterial and venous glandular branches were measured using sliding caliper. RESULTS: The submandibular gland was mainly supplied by the facial artery and submental artery, partly by the lingual artery and external jugular artery. The venous drainage of the submandibualr gland occurred through the anterior facial vein, the venae comitantes of facial artery, the vein close to the Whaston's duct (the hilum vein), and seldom drained to external jugular vein and other veins. CONCLUSIONS: The anatomy of SMG is a complicated structure. Determining the main blood vessels of the submandibular gland is very important to achieve a successful vascularized autologous SMG transplant.

[Eye socket reconstruction with free flap].

OBJECTIVE: To discuss the effect of eye reconstruction with free flap. METHODS: Free flap was used in 21 patients of contracted eye socket and anophthalmos. The forearm free flap was utilized in 19 patients,the scapular flap in 2. Free flap with microvascular anastomoses was transferred into contracted eye socket. And hydroxyapatite implant was selectively inserted for intraorbital implantation according to the extent of contracted eye socket postoperation. Eye socket was reconstructed in one stage operation. RESULTS: The flaps were transferred successfully in all patients. All patients were followed up between 4 to 42 months, better cosmetic results were achieved and well-fitted eye prosthesis was weaned. CONCLUSION: Free flap is a useful alternative in treatment of severe contracted eye socket.

[Management of blood vessels in the vascularized autogenous submandibular gland transfer for severe keratoconjunctivitis sicca].

OBJECTIVE: To summarize the management of blood vessels in the transfer of vascularized autogenous submandibular gland. METHODS: Sixty-eight cases of vascularized transfer of autogenous submandibular gland for severe keratoconjunctivitis sicca performed from August 1999 to April 2004 were reviewed. Data collected for each patient included general items, donor and recipient vessels, vessel crisis, salvage of the vessel thrombosis, and survival of transferred glands. RESULTS: Among the 68 cases, all the donor and recipient arteries were facial artery and superficial temporal artery respectively. For donor veins, 55 were facial veins, 1 was vein near the duct, and 12 were venae comitantes of facial artery. For recipient veins, 62 were superficial temporary veins and five were veins in the upper neck, one was deep temporary vein. Vessel thromboses occurred in 10 cases, 9 were venous and 1 were arterial. The salvage rate was 10.0%, with the overall survival rate of 86.8% of transferred gland. CONCLUSIONS: Variation in venous outflow is common in microvascular transfer of submandibular gland, and anastomosis between venae comitante of facial artery and superficial temporal vein is most dependable. Vessel anastomosis under microscope may reduce the vessel thrombosis rate after operation.

[Eye socket reconstruction with free radial forearm flap in anophthalmic orbital syndrome and contracted eye socket].

OBJECTIVE: To assess the effect of eye socket reconstruction with free radial forearm flap. METHODS: Reconstructive procedures were performed in 7 patients underwent orbital exenteration for malignant tumors and in 9 patients underwent enucleation and postoperative irradiation of the orbit for the treatment of retinoblastoma. These patients were suffered from anophthalmic orbital syndrome and contractive eye socket. A microvascular surgical technique with a free radial forearm flap was adopted. Hydroxyapatite implant was inserted as an intraorbital implantation. RESULTS: All patients were followed up for 6 months to 5 years and good cosmetic results were obtained. A large eye socket was achieved permanently. Artificial eye could be fitted with satisfactory results. CONCLUSION: Free radial forearm flap transplantation offers a useful option for the treatment of anophthalmic orbital syndrome.