Few-layer MoS2 as nitrogen protective barrier.

We report experimental and theoretical investigations of the observed barrier behavior of few-layer MoS2 against nitrogenation. Owing to its low-strength shearing, low friction coefficient, and high lubricity, MoS2 exhibits the demeanor of a natural N-resistant coating material. Raman spectroscopy is done to determine the coating capability of MoS2 on graphene. Surface morphology of our MoS2/graphene heterostructure is characterized by using optical microscopy, scanning electron microscopy, and atomic force microscopy. In addition, density functional theory-based calculations are performed to understand the energy barrier performance of MoS2 against nitrogenation. The penetration of nitrogen atoms through a defect-free MoS2 layer is prevented by a very high vertical diffusion barrier, indicating that MoS2 can serve as a protective layer for the nitrogenation of graphene. Our experimental and theoretical results show that MoS2 material can be used both as an efficient nanocoating material and as a nanoscale mask for selective nitrogenation of graphene layer.

Bone anchor infections in female pelvic reconstructive procedures: a literature review of series and case reports.

PURPOSE: We determined the reported prevalence of infectious osseous complications due to the use of bone anchors for suture fixation in female pelvic reconstructive procedures. In addition, the type and method of bone anchors as well as the reported pathogens associated with osseous infections were reviewed. MATERIALS AND METHODS: Primary reported series of female pelvic reconstructive procedures involving bone anchor suture fixation referenced in Index Medicus from January 1990 to July 2000 were extracted using the MEDLINE bibliographic database on English language articles involving humans. All case reports of infectious osseous complications due to bone anchor use in female reconstructive procedures were also reviewed during this period. RESULTS: Since the inception of bone anchor suture fixation for female pelvic reconstructive procedures 10 years ago, the overall prevalence of related infectious complications has been 6 cases in 1,018 procedures (0.6%). This type of adverse event developed between followup weeks 1 and 24. The prevalence of suprapubic bone anchors has been 6 cases in 698 procedures (0.86%). For transvaginal bone anchor procedures no infectious cases have been reported in the combined series of 314 procedures and the same is true for 1 reported case of sacral bone anchor placement in 6 procedures. No statistical difference was noted in regard to the prevalence of infection in procedures involving suprapubic bone anchors and transvaginal bone anchor combined with sacral bone anchor placement (Fisher's exact test p = 0.19). The organisms reported in case reports suggest a coliform, skin or hematogenous source for contamination of the bone anchor site. CONCLUSIONS: An infectious bone anchor complication in female pelvic reconstructive procedures is an uncommon event with a reported prevalence of 0.6%. Currently there is no evidence of differences in the prevalence of osseous complications after transvaginal versus suprapubic bone anchor fixation. Preoperative broad-spectrum antibiotics are recommended to decrease the potential of infectious bone anchor complications.