Golden interfaces: The Surface of Self-Assembled Monolayers

Self-assembled monolayers (SAMs) of alkanethiols and disulfides on gold form organic interfaces with properties largely controlled by the end groups of the molecules composing the film. SAMs provide a unique link between the science of organic surfaces and technologies that seek to exploit their adaptable character. Many techniques are useful for probing the structure of SAMs although only scanning tunneling microscopy (STM) at picoamperes reveals the details of the packing of their end groups at the sub-angstrom level. This review demonstrates that STM effectively tests new types of control over the microscopic structure–property relationships characteristic of SAMs on gold that should prove useful to their application.     

Buchbesprechungen

Ohne Zusammenfassung

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Book reviews

     

Telephone booster sessions for optimizing smoking cessation for patients in rehabilitation centers.

Smokers with smoking-related diseases who are hospitalized in rehabilitation centers should be offered smoking cessation. This is the first study evaluating whether telephone booster sessions after intensive inpatient treatment are an effective strategy. The present study was conducted in 13 rehabilitation centers for somatic disorders as a prospective multicenter study with a randomized treatment-control group design. We compared abstinence rates after hospital discharge from treatment that included a group smoking cessation program with (treatment group) and without telephone booster sessions (control group). Data from 290 smokers were analyzed. After 6 and 12 months the treatment group achieved abstinence rates twice as high as those of the control group. Men profited more from telephone booster sessions than did women. Results indicated that telephone booster sessions were highly effective (even) after an inherently intensive group program during a hospital stay. Further research should focus on the special needs of women receiving telephone counseling.     

A new technique for on-line and off-line high speed computation

A novel technique for both online and offline computation is presented. With this technique, a reconstruction analysis in elementary particle physics, otherwise prohibitively long, has been accomplished. It will be used online in an upcoming Fermilab experiment to reconstruct more than 100000 events per second and to trigger on the basis of that information. The technique delivers 40 gigaoperations per second, has a bandwidth on the order of gigabytes per second, and has a modest cost. An overview of the program, details of the system, and performance measurements are presented     

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Ohne Zusammenfassung     

Factor XIIIa immunoreactivity in primary and secondary tumours of the meninges

Occasionally variants of meningeal hemangiopericytomas (HPC) may be confused with primary and secondary tumours of the meninges by virtue of their features and patterns of growth. Until now, a specific immunohistochemical marker for HPC could not be identified. HPC are reported to express factor XIIIa (F XIIIa) in the cytoplasm of the tumour cells. In an effort to assess the diagnostic value of F XIIIa for meningeal HPC, we investigated 38 primary meningeal tumours (6 HPC, 28 meningiomas of various subtypes, 4 meningeal sarcomas) and 23 secondary meningeal tumors (8 metastatic carcinomas, 6 gliosarcomas, 9 anaplastic gliomas) with anti-F XIIIa antibody. All HPC revealed 5%-20% of F-XIIIa-positive neoplastic cells. Malignant fibrous histiocytomas and gliosarcomas with MFH-like structures also exhibited multiple F-XIIIa-positive cells. Most of the F-XIIIa-positive cells in meningiomas were identified as macrophages. Furthermore, there was a population of small dark cells of uncertain histogenesis. Cells with positive immunoreactivity for F-XIIIa in metastatic carcinomas and gliomas apparently were of macrophage lineage. Though, in some cases, it would have been difficult to distinguish reactive from neoplastic cells without simultaneous immunohistochemical investigation with antibodies for macrophages, cytokeratin, EMA and GFAP. Because of these uncertainties, wo believe that the potential of F XIIIa-antibody in obtaining precise differential diagnostic information is limited.     

Danckwerts’ law for mean residence time revisited

This paper shows that Danckwerts’ law for mean residence time in a vessel with continuous and steady throughflow holds for a stochastic model based on a Markov chain for the particle spatial position, under a set of three very general conditions on the transfer probabilities. These are natural conditions and represent mass balance conditions on the transfer between spatial regions in the process. It is shown that a stochastic model for particle residence time distribution with these three conditions may describe almost any physical flow configuration, and also covers published mathematical RTD models, independent of their mathematical form or the nature of the associated boundary conditions, models for which Danckwert's law has hitherto been shown to be satisfied on a case-by-case basis. Two examples, namely those birth-death Markov chains and fluidized bed models are discussed.