Graphene-Silicon Layered Structures on Single-crystalline Ir(111) Thin Films

Single-crystalline transition metal films are ideal playing fields for the epitaxial growth of graphene and graphene-base materials. Graphene-silicon layered structures were successfully constructed on Ir(111) thin film on Si substrate with an yttria-stabilized zirconia buffer layer via intercalation approach. Such hetero-layered structures are compatible with current Si-based microelectronic technique, showing high promise for applications in future micro- and nano-electronic devices.Comment: 14 pages, 6 figure

Defensin-related peptide 1 (Defr1) is allelic to Defb8 and chemoattracts immature DC and CD4+ T cells independently of CCR6

β-Defensins comprise a family of cationic, antimicrobial and chemoattractant peptides. The six cysteine canonical motif is retained throughout evolution and the disulphide connectivities stabilise the conserved monomer structure. A murine β-defensin gene (Defr1) present in the main defensin cluster of C57B1/6 mice, encodes a peptide with only five of the canonical six cysteine residues. In other inbred strains of mice, the allele encodes Defb8, which has the six cysteine motif. We show here that in common with six cysteine β-defensins, defensin-related peptide 1 (Defr1) displays chemoattractant activity for CD4+ T cells and immature DC (iDC), but not mature DC cells or neutrophils. Murine Defb2 replicates this pattern of attraction. Defb8 is also able to attract iDC but not mature DC. Synthetic analogues of Defr1 with the six cysteines restored (Defr1 Y5C) or with only a single cysteine (Defr1-1cV) chemoattract CD4+ T cells with reduced activity, but do not chemoattract DC. β-Defensins have previously been shown to attract iDC through CC receptor 6 (CCR6) but neither Defr1 or its related peptides nor Defb8, chemoattract cells overexpressing CCR6. Thus, we demonstrate that the canonical six cysteines of β-defensins are not required for the chemoattractant activity of Defr1 and that neither Defr1 nor the six cysteine polymorphic variant allele Defb8, act through CCR6

Probing Mechanical Properties of Graphene with Raman Spectroscopy

The use of Raman scattering techniques to study the mechanical properties of graphene films is reviewed here. The determination of Gruneisen parameters of suspended graphene sheets under uni- and bi-axial strain is discussed and the values are compared to theoretical predictions. The effects of the graphene-substrate interaction on strain and to the temperature evolution of the graphene Raman spectra are discussed. Finally, the relation between mechanical and thermal properties is presented along with the characterization of thermal properties of graphene with Raman spectroscopy.Comment: To appear in the Journal of Materials Scienc

Uncemented and cemented primary total hip arthroplasty in the Swedish Hip Arthroplasty Register: Evaluation of 170,413 operations

BACKGROUND AND PURPOSE: Since the introduction of total hip arthroplasty (THA) in Sweden, both components have most commonly been cemented. A decade ago the frequency of uncemented fixation started to increase, and this change in practice has continued. We therefore analyzed implant survival of cemented and uncemented THA, and whether the modes of failure differ between the two methods of fixation. PATIENTS AND METHODS: All patients registered in the Swedish Hip Arthroplasty Register between 1992 and 2007 who received either totally cemented or totally uncemented THA were identified (n = 170,413). Kaplan-Meier survival analysis with revision of any component, and for any reason, as the endpoints was performed. Cox regression models were used to calculate risk ratios (RRs) for revision for various reasons, adjusted for sex, age, and primary diagnosis. RESULTS: Revision-free 10-year survival of uncemented THA was lower than that of cemented THA (85% vs. 94%, p < 0.001). No age or diagnosis groups benefited from the use of uncemented fixation. Cox regression analysis confirmed that uncemented THA had a higher risk of revision for any reason (RR = 1.5, 95% CI: 1.4-1.6) and for aseptic loosening (RR = 1.5, CI: 1.3-1.6). Uncemented cup components had a higher risk of cup revision due to aseptic loosening (RR = 1.8, CI: 1.6-2.0), whereas uncemented stem components had a lower risk of stem revision due to aseptic loosening (RR = 0.4, CI: 0.3-0.5) when compared to cemented components. Uncemented stems were more frequently revised due to periprosthetic fracture during the first 2 postoperative years than cemented stems (RR = 8, CI: 5-14). The 5 most common uncemented cups had no increased risk of revision for any reason when compared with the 5 most commonly used cemented cups (RR = 0.9, CI: 0.6-1.1). There was no significant difference in the risk of revision due to infection between cemented and uncemented THA. INTERPRETATION: Survival of uncemented THA is inferior to that of cemented THA, and this appears to be mainly related to poorer performance of uncemented cups. Uncemented stems perform better than cemented stems; however, unrecognized intraoperative femoral fractures may be an important reason for early failure of uncemented stems. The risk of revision of the most common uncemented cup designs is similar to that of cemented cups, indicating that some of the problems with uncemented cup fixation may have been solved.Open Access - This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the source is credited

Oxalic acid in clear and cloudy atmospheres: Analysis of data from International Consortium for Atmospheric Research on Transport and Transformation 2004

Oxalic acid is often the leading contributor to the total dicarboxylic acid mass in ambient organic aerosol particles. During the 2004 International Consortium for Atmospheric Research on Transport and Transformation (ICARTT) field campaign, nine inorganic ions (including SO_4^(2−)) and five organic acid ions (including oxalate) were measured on board the Center for Interdisciplinary Remotely Piloted Aircraft Studies (CIRPAS) Twin Otter research aircraft by a particle-into-liquid sampler (PILS) during flights over Ohio and surrounding areas. Five local atmospheric conditions were studied: (1) cloud-free air, (2) power plant plume in cloud-free air with precipitation from scattered clouds overhead, (3) power plant plume in cloud-free air, (4) power plant plume in cloud, and (5) clouds uninfluenced by local pollution sources. The aircraft sampled from two inlets: a counterflow virtual impactor (CVI) to isolate droplet residuals in clouds and a second inlet for sampling total aerosol. A strong correlation was observed between oxalate and SO_4^(2−) when sampling through both inlets in clouds. Predictions from a chemical cloud parcel model considering the aqueous-phase production of dicarboxylic acids and SO_4^(2−) show good agreement for the relative magnitude of SO_4^(2−) and oxalate growth for two scenarios: power plant plume in clouds and clouds uninfluenced by local pollution sources. The relative contributions of the two aqueous-phase routes responsible for oxalic acid formation were examined; the oxidation of glyoxylic acid was predicted to dominate over the decay of longer-chain dicarboxylic acids. Clear evidence is presented for aqueous-phase oxalic acid production as the primary mechanism for oxalic acid formation in ambient aerosols

Targeting deficiencies in the TLR5 mediated vaginal response to treat female recurrent urinary tract infection

Abstract The identification of the host defence peptides as target effectors in the innate defence of the uro-genital tract creates new translational possibilities for immunomodulatory therapies, specifically vaginal therapies to treat women suffering from rUTI, particularly those carrying the TLR5_C1174T SNP. Urinary tract infections (UTIs) are a microbial disease reported worldwide. Women are particularly susceptible with many suffering debilitating recurrent (r) infections. Treatment is by antibiotics, but such therapy is linked to antibiotic resistance and re-infection. This study explored the innate protective mechanisms of the urogenital tract with the aim of boosting such defences therapeutically. Modelling UTIs in vitro, human vaginal and bladder epithelial cells were challenged with uropathogenic Escherichia coli (CFT073) and microbial PAMPs including flagellin, LPS and peptidoglycan. Flagellin functioning via the TLR5/NFκB pathway was identified as the key UPEC virulence factor causing a significant increase (P < 0.05) in the production of the host-defence peptide (HDP), BD2. BD2-depleted urine samples from bladder infected mice supported increased UPEC growth, strengthening the significance of the HDPs in protecting the urogenital tissues from infection. Clinically, vaginal-douche BD2 concentrations were reduced (p < 0.05) in women suffering rUTIs, compared to age-matched healthy controls with concentrations further decreased (p < 0.05) in a TLR5392Stop SNP rUTI subgroup. Topical vaginal estrogen treatment increased (p < 0.001) BD2 concentrations in all women, including those carrying the SNP. These data identify therapeutic and antibiotic sparing roles for vaginal immunomodulatory agents that specifically target HDP induction, facilitate bacterial killing and disrupt the UPEC infection cycle

Anti-Bacterial Effects of Poly-N-Acetyl-Glucosamine Nanofibers in Cutaneous Wound Healing: Requirement for Akt1

Treatment of cutaneous wounds with poly-N-acetyl-glucosamine nanofibers (sNAG) results in increased kinetics of wound closure in diabetic animal models, which is due in part to increased expression of several cytokines, growth factors, and innate immune activation. Defensins are also important for wound healing and anti-microbial activities. Therefore, we tested whether sNAG nanofibers induce defensin expression resulting in bacterial clearance.The role of sNAG in defensin expression was examined using immunofluoresence microscopy, pharmacological inhibition, and shRNA knockdown in vitro. The ability of sNAG treatment to induce defensin expression and bacterial clearance in WT and AKT1-/- mice was carried out using immunofluoresent microscopy and tissue gram staining. Neutralization, using an antibody directed against β-defensin 3, was utilized to determine if the antimicrobial properties of sNAG are dependent on the induction of defensin expression.sNAG treatment causes increased expression of both α- and β-type defensins in endothelial cells and β-type defensins in keratinocytes. Pharmacological inhibition and shRNA knockdown implicates Akt1 in sNAG-dependent defensin expression in vitro, an activity also shown in an in vivo wound healing model. Importantly, sNAG treatment results in increased kinetics of wound closure in wild type animals. sNAG treatment decreases bacterial infection of cutaneous wounds infected with Staphylococcus aureus in wild type control animals but not in similarly treated Akt1 null animals. Furthermore, sNAG treatment of S. aureus infected wounds show an increased expression of β-defensin 3 which is required for sNAG-dependent bacterial clearance. Our findings suggest that Akt1 is involved in the regulation of defensin expression and the innate immune response important for bacterial clearance. Moreover, these findings support the use of sNAG nanofibers as a novel method for enhancing wound closure while simultaneously decreasing wound infection

Polyethylene Oxidation in Total Hip Arthroplasty: Evolution and New Advances

Ultra-high molecular weight polyethylene (UHMWPE) remains the gold standard acetabular bearing material for hip arthroplasty. Its successful performance has shown consistent results and survivorship in total hip replacement (THR) above 85% after 15 years, with different patients, surgeons, or designs

Leukocyte Attraction by CCL20 and Its Receptor CCR6 in Humans and Mice with Pneumococcal Meningitis

We previously identified CCL20 as an early chemokine in the cerebrospinal fluid (CSF) of patients with pneumococcal meningitis but its functional relevance was unknown. Here we studied the role of CCL20 and its receptor CCR6 in pneumococcal meningitis. In a prospective nationwide study, CCL20 levels were significantly elevated in the CSF of patients with pneumococcal meningitis and correlated with CSF leukocyte counts. CCR6 deficient mice with pneumococcal meningitis and WT mice with pneumococcal meningitis treated with anti-CCL20 antibodies both had reduced CSF white blood cell counts. The reduction in CSF pleocytosis was also accompanied by an increase in brain bacterial titers. Additional in vitro experiments showed direct chemoattractant activity of CCL20 for granulocytes. In summary, our results identify the CCL20-CCR6 axis as an essential component of the innate immune defense against pneumococcal meningitis, controlling granulocyte recruitment