ABSTRACT
The structures of inkjet coatings commonly contain a high concentration of fine diameter pores together with a large pore volume capacity. To clarify the interactive role of the porous structure and the coincidentally occurring swelling of binder during inkjet ink vehicle imbibition, coating structures were studied in respect to their absorption behaviour for polar and non-polar liquid. The absorption measurement was performed using compressed pigment tablets, based on a range of pigment types and surface charge polarity, containing either polyvinyl alcohol (PVOH) or styrene acrylic latex (SA) as the binder, by recording the liquid uptake with a microbalance. The results indicate that, at the beginning of liquid uptake, at times less than 2 s, the small pores play the dominant role with respect to the inkjet ink vehicle imbibition. Simultaneously, water molecules diffuse into and within the hydrophilic PVOH binder causing binder swelling, which diminishes the number of active small pores and reduces the diameter of remaining pores, thus slowing the capillary flow as a function of time. The SA latex does not absorb the vehicle, and therefore the dominating phenomenon is then capillary absorption. However, the diffusion coefficient of the water vapour across separately prepared PVOH and SA latex films seems to be quite similar. In the PVOH, the polar liquid diffuses into the polymer network, whereas in the SA latex the hydrophobic nature prevents the diffusion into the polymer matrix and there exists surface diffusion. At longer timescale, permeation flow into the porous coating dominates as the resistive term controlling the capillary driven liquid imbibition rate.
ABSTRACT
The results of a 2-year treatment study of children with learning problems are reported. During the first treatment year, half of the children participated in a multifaceted neurocognitive treatment and the other half in a treatment that provided supervision of school tasks and peer group support. During the second treatment year, all children participated in the neurocognitive treatment. The participants were 74 Chilean children 6 to 11 years old. The issues under investigation were the effect of treatment duration, and the relationship between pretreatment neurocognitive and behavioral characteristics and academic treatment outcome. The results indicated that significant gains occurred during both the first and the second treatment year. No major differences were found between the treatment groups. Pretreatment negative behavioral traits were associated with lesser academic growth in the group participating in the homework supervision treatment but not in the neurocognitive treatment group.
Subject(s)
Cognitive Behavioral Therapy , Learning Disabilities/therapy , Psychotherapy, Group , Analysis of Variance , Chi-Square Distribution , Child , Child Behavior , Female , Humans , Learning Disabilities/psychology , Male , Time Factors , Treatment OutcomeABSTRACT
The purpose of the study was to analyze the relative efficacies of two treatments for children with learning difficulties. The first treatment consisted of multiple training components targeting specific cognitive and behavioral factors; the second treatment provided emotional support and supervision of school tasks. The participants were 94 Chilean schoolchildren (6 to 11 years of age). The efficacies were compared on (a) neurocognitive tests, (b) school achievement tests, and (c) behavior in school and at home. The results indicated that both groups improved on most of the outcome measures. The first group showed best results in parents' rating of home behavior, and the second group in reading. The findings also emphasized the importance of emotional support and the inclusion of a parents' group in treatment for children with learning difficulties.
