Properties of nanoporous organosilicate hybrid thin films with a bimodal pore size distribution

Low dielectric poly[methylsilsesquioxane‐ran‐trifluoropropylsilsesquioxane‐ran‐(2,4,6,8‐tetramethyl‐2,4,6,8‐tetraethylenecyclotetrasiloxane)silsesquioxane]s {P[M‐ran‐TFP‐ran‐(TCS)]SSQs} having various compositions were synthesized using trifluoropropyl trimethoxysilane, methyl trimethoxysilane and 2,4,6,8‐tetramethyl‐2,4,6,8‐tetra(trimethoxysilylethyl)cyclotetrasiloxane. The chemical composition of the polymers and the content of SiOH end‐groups were controlled by adjusting the reaction conditions, and they were characterized by ¹H‐NMR. The thermally decomposable trifluoropropyl groups on the P[M‐ran‐TFP‐ran‐(TCS)]SSQ backbone and heptakis(2,3,6‐tri‐O‐methyl)‐β‐cyclodextrin (CD) were employed as pore generators. The dielectric constants of the porous CD/P[M‐ran‐TFP‐ran‐(TCS)]SSQ films were in the range 2.0–2.7 (at 100 kHz) depending on the concentration of the porogens, and showed no change over 4 days under aqueous conditions. The pore size of the films showed a bimodal distribution, with diameters of ca 0.5–1.0 nm for those originating from the trifluoropropyl groups and 1.7 nm from the CD. The elastic modulus and hardness of the 30 vol% CD‐blended film with a dielectric constant of 2.26 were 2.40 and 0.38 GPa, respectively, as determined by a nanoindenter. Copyright © 2005 Society of Chemical Industry     

Laboratory issues in the detection and reporting of antibacterial resistance

The emergence of antimicrobial resistance among several common bacterial pathogens requires that clinical microbiology laboratories have the ability to promptly and accurately recognize resistance in patients' isolates. Laboratories have several options for performing routine susceptibility testing, including the broth microdilution procedure (with or without instrumentation for test reading), automated instrument systems that provide rapid results, antibiotic gradient diffusion, and disk diffusion procedures. In addition, there are definitive screening tests capable of recognizing resistance to drugs of choice among several common bacterial species based on single drug concentration tests or rapid spot tests. The likely emergence of still newer resistance mechanisms will provide a challenge to clinical microbiologists to devise accurate, yet cost-effective strategies for use in the future.     

What is new in bladder cancer imaging

Treatment and prognosis of urinary bladder cancer largely are determined by the tumor stage and presence of metastases. MR imaging and clinical staging complement each other. MR imaging is the most accurate technique for differentiating the various stages of deep tumor infiltration and detection of metastases, whereas clinical staging is the best technique for differentiating between postbiopsy effects and the various stages of superficial tumors. The role of MR imaging in staging of this disease and monitoring of therapy is reviewed and illustrated. Finally, the authors present an overview of current and future applications of this technique.     

A prospective study of hyperactive boys with conduct problems and normal boys: adolescent and adult criminality

OBJECTIVE: To examine the relationship between attention deficit disorder with hyperactivity in childhood and criminality in adolescence and adulthood in 89 hyperactive and 87 normal control subjects. METHOD: In this prospective study, adolescent follow-up intervals ranged from 13 to 21 years and adult follow-up ranged from 18 to 23 years. The official arrest records for all subjects were obtained. RESULTS: Hyperactive subjects had significantly higher juvenile (46% versus 11%) and adult (21% versus 1%) arrest rates. Juvenile and adult incarceration rates were also significantly higher. Childhood conduct problems predicted later criminality, and serious antisocial behavior in adolescence predicted adult criminality. CONCLUSIONS: Hyperactive children are at risk for both juvenile and adult criminality. The risk for becoming an adult offender is associated with conduct problems in childhood and serious antisocial behavior (repeat offending) in adolescence. Hyperactive children who do not have conduct problems are not at increased risk for later criminality.