From Graphene Nanoribbons on Cu(111) to Nanographene on Cu(110): Critical Role of Substrate Structure in the Bottom-Up Fabrication Strategy.

Bottom-up strategies can be effectively implemented for the fabrication of atomically precise graphene nanoribbons. Recently, using 10,10'-dibromo-9,9'-bianthracene (DBBA) as a molecular precursor to grow armchair nanoribbons on Au(111) and Cu(111), we have shown that substrate activity considerably affects the dynamics of ribbon formation, nonetheless without significant modifications in the growth mechanism. In this paper we compare the on-surface reaction pathways for DBBA molecules on Cu(111) and Cu(110). Evolution of both systems has been studied via a combination of core-level X-ray spectroscopies, scanning tunneling microscopy, and theoretical calculations. Experimental and theoretical results reveal a significant increase in reactivity for the open and anisotropic Cu(110) surface in comparison with the close-packed Cu(111). This increased reactivity results in a predominance of the molecular-substrate interaction over the intermolecular one, which has a critical impact on the transformations of DBBA on Cu(110). Unlike DBBA on Cu(111), the Ullmann coupling cannot be realized for DBBA/Cu(110) and the growth of nanoribbons via this mechanism is blocked. Instead, annealing of DBBA on Cu(110) at 250 °C results in the formation of a new structure: quasi-zero-dimensional flat nanographenes. Each nanographene unit has dehydrogenated zigzag edges bonded to the underlying Cu rows and oriented with the hydrogen-terminated armchair edge parallel to the [1-10] direction. Strong bonding of nanographene to the substrate manifests itself in a high adsorption energy of -12.7 eV and significant charge transfer of 3.46e from the copper surface. Nanographene units coordinated with bromine adatoms are able to arrange in highly regular arrays potentially suitable for nanotemplating.

Ni-Cu ion exchange observed for Ni(II)-porphyrins on Cu(111).

A Ni-Cu ion exchange has been observed for (5,15-dibromo-10,20-diphenylporphyrinato)nickel(II) (NiDBrDPP) and (5,10,15,20-tetrakis(4-bromophenyl)porphyrinato)nickel(II) (NiTBrPP) on Cu(111). The ion exchange proceeds at a faster rate for the NiDBrDPP/Cu(111) system compared to NiTBrPP/Cu(111). This is explained in terms of the macrocycle-substrate distance and the distortions that occur when the molecules are deposited on the Cu(111) surface.

Effect of delayed lumbar punctures on the diagnosis of acute bacterial meningitis in adults.

INTRODUCTION: Bacterial meningitis is a medical emergency, the outcome of which is improved by prompt antibiotic treatment. For patients with suspected meningitis and no features of severe disease, the British Infection Society recommends immediate lumbar puncture (LP) before antibiotics, to maximise the chance of a positive cerebrospinal (CSF) culture. In such patients, CT scanning before LP is not needed. METHODS: The case notes of adults with meningitis admitted to a large district general hospital over 3 years were reviewed. Patients were classified as Likely Bacterial Meningitis or Likely Viral Meningitis based on their CSF and peripheral blood results using the Meningitest Criteria, with microbiological and virological confirmation. RESULTS: Of 92 patients studied, 24 had Likely Bacterial Meningitis, including 16 with microbiologically confirmed disease (none had PCR tests for bacteria). Sixty-eight had Likely Viral Meningitis, four of whom had viral PCR, including one with herpes simplex virus. No patient had an LP before antibiotics. CSF culture was positive for eight (73%) of the 11 patients who had an LP up to 4 h after starting antibiotics, compared with eight (11%) of 71 patients with a later LP (p<0.001). None of the 34 LPs performed more than 8 h after antibiotics was culture-positive. For 62 (67%) of the 92 patients, the delay was due to a CT scan, although only 20 of these patients had a contraindication to an immediate LP. CONCLUSIONS: Too many patients with acute bacterial meningitis are being sent for unnecessary CT scans, causing delays in the LP, and reducing the chances of a positive CSF culture after starting antibiotics. However, even if antibiotics have been started, an LP within 4 h is still likely to be positive. Molecular tests for diagnosis should also be requested.

Localized tufts of fibrils on Staphylococcus epidermidis NCTC 11047 are comprised of the accumulation-associated protein.

Staphylococcus epidermidis is both a human skin commensal and an opportunistic pathogen, causing infections linked to implanted medical devices. This paper describes localized tufts of fibrillar appendages on a subpopulation (25%) of wild-type (WT) S. epidermidis NCTC 11047 cells. The fibrils (122.2 +/- 10.8 nm long) are usually in a lateral position on the cells. Fibrillar (Fib(+)) and nonfibrillar (Fib(-)) subpopulations were separated (enriched) by 34 sequential partitions of WT cells between a buffer phase and a hexadecane phase. Following enrichment, hydrophobic cells from the hexadecane phase comprised 70% Fib(+) cells and the less hydrophobic cells from the buffer phase entirely comprised Fib(-) cells. The Fib(+) and Fib(-) subpopulations did not revert on subculture (34 times) on solid medium. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of cell surface proteins from WT, Fib(+), and Fib(-) cells revealed two high-molecular-mass proteins (280 kDa and 230 kDa) on the WT and Fib(+) cells that were absent from the Fib(-) cells. Amino acid sequencing revealed that fragments of both the 280- and 230-kDa proteins had 100% identity to the accumulation-associated protein (Aap). Aap is known to cause biofilm formation if it is truncated by loss of the terminal A domain. Immunogold staining with anti-Aap antibodies labeled tuft fibrils of the WT and Fib(+) cells but not the cell surface of Fib(-) cells. The tufts were labeled with N-terminally directed antibodies (anti-A domain), showing that the fibrillar Aap was not truncated on the cell surface. Thus, the presence of full-length Aap correlated with the low biofilm-forming abilities of both WT and Fib(+) S. epidermidis NCTC 11047 populations. Reverse transcription-PCR showed that aap was transcribed in both Fib(+) and Fib(-) cells. We therefore propose that full-length Aap is expressed on cells of S. epidermidis NCTC 11047 as tufts of short fibrils and that fibril expression is regulated at a posttranscriptional level.