Fluoridated elastomers: Effect on the microbiology of plaque

The objective of this study was to investigate the effect of fluoridated elastomeric ligatures on the microbiology of local dental plaque in vivo. This randomized, prospective, longitudinal, clinical trial had a split-mouth crossover design. The subjects were 30 patients at the beginning of their treatment with fixed orthodontic appliances in the orthodontic departments of the Liverpool and the Sheffield dental hospitals in the United Kingdom. The study consisted of 2 experimental periods of 6 weeks with a washout period between. Fluoridated elastomers were randomly allocated at the first visit to be placed around brackets on tooth numbers 12, 11, 33 or 22, 21, 43. Nonfluoridated elastomers were placed on the contralateral teeth. Standard nonantibacterial fluoridated toothpaste and mouthwash were supplied. After 6 weeks (visit 2), the elastomers were removed, placed in transport media, and plated on agar within 2 hours. Nonfluoridated elastomers were placed on all brackets for 1 visit to allow for a washout period. At visit 3, fluoridated elastomers were placed on the teeth contralateral to those that received them at visit 1. At visit 4, the procedures at visit 2 were repeated. Samples were collected on visits 2 and 4. A logistic regression was performed, with the presence or absence of streptococcal or anaerobic growth as the dependent variable. A mixed-effects analysis of variance was carried out with the percentage of streptococcal or anaerobic bacterial count as the dependent variable. The only significant independent variables were the subject variable (P = < .001) for the percentage of streptococcal and anaerobic bacterial count and the visit variable for the percentage of streptococcal count (P = < .001). The use of fluoridated or nonfluoridated elastomers was not significant for percentage of either streptococcal (P = .288) or anaerobic count (P = .230). Fluoridated elastomers are not effective at reducing local streptococcal or anaerobic bacterial growth after a clinically relevant time in the mouth

Modes of alphabet letter production during middle childhood and adolescence: Interrelationships with each other and other writing skills

Although handwriting is typically taught during early childhood and keyboarding may not be taught explicitly, both may be relevant to writing development in the later grades. Thus, Study 1 investigated automatic production of the ordered alphabet from memory for manuscript (unjoined), cursive (joined), and keyboard letter modes (alphabet 15 sec) and their relationships with each other and spelling and composing in typically developing writers in grades 4 to 7 (N = 113). Study 2 compared students with dysgraphia (impaired handwriting, n=27), dyslexia (impaired word spelling, n=40), or oral and written language learning disability (OWL LD) (impaired syntax composing, n=11) or controls without specific writing disabilities (n=10) in grades 4 to 9 (N=88) on the same alphabet 15 modes, manner of copying (best or fast), spelling, and sentence composing. In Study 1, sequential multilevel model regressions of predictor alphabet 15 letter production/selection modes on spelling and composition outcomes, measured annually from grade 4 to grade 7 (ages 9 to 13 years), showed that only the cursive mode uniquely, positively, and consistently predicted both spelling and composing in each grade. For composing, in grade 4 manuscript mode was positively predictive and in grades 5-7 keyboard selection was. In Study 2 all letter production modes correlated with each other and one’s best and fast sentence copying, spelling, and timed sentence composing. The groups with specific writing disabilities differed from control group on alphabet 15 manuscript mode, copy fast, and timed sentence composing. The dysgraphia and dyslexia groups differed on copying sentences in one’s best handwriting, with the dysgraphia group scoring lower. The educational and theoretical significance of the findings are discussed for multiple modes and manners of letter production/selection of the alphabet that support spelling and composing beyond the early grades in students with and without specific writing disabilities

Electrical Resistivity of Lanthanum, Praseodymium, Neodymium, and Samarium

The electrical resistivities of polycrystalline samples of La, Pr, Nd, and Sm are reported in the temperature range 1.3 to 300 deg K. La exhibits a superconducting transition at 5.8 deg K. The curve for Pr has slope changes at 61 and 95 deg K. The Nd curve shows small jumps at 5 and 20 deg K. Sm shows slope changes at 14 and 106 deg K. (auth

Forced Solid-State Interactions for the Selective “Turn-On” Fluorescence Sensing of Aluminum Ions in Water Using a Sensory Polymer Substrate

Selective and sensitive solid sensory substrates for detecting Al(III) in pure water are reported. The material is a flexible polymer film that can be handled and exhibits gel behavior and membrane performance. The film features a chemically anchored salicylaldehyde benzoylhydrazone derivative as an aluminum ion fluorescence sensor. A novel procedure for measuring Al(III) at the ppb level using a single solution drop in 20 min was developed. In this procedure, a drop was allowed to enter the hydrophilic material for 15 min before a 5 min drying period. The process forced the Al(III) to interact with the sensory motifs within the membrane before measuring the fluorescence of the system. The limit of detection of Al(III) was 22 ppm. Furthermore, a water-soluble sensory polymer containing the same sensory motifs was developed with a limit of detection of Al(III) of 1.5 ppb, which was significantly lower than the Environmental Protection Agency recommendations for drinking water.Spanish Ministerio de Economía y Competitividad-Feder (MAT2011-22544) and by the Consejería de Educación - Junta de Castilla y León (BU232U13)