Electron-beam-initiated polymerization of poly(ethylene glycol)-based wood impregnants

The current study demonstrates that methacrylate and acrylate poly(ethylene glycol) (PEG) functional oligomers can be effectively impregnated into wood blocks, and cured efficiently to high conversions without catalyst by e-beam radiation, allowing for less susceptibility to leaching, and favorable properties including higher Brinell hardness values. PEG based monomers were chosen because there is a long history of this water-soluble monomer being able to penetrate the cell wall, thus bulking it and decreasing the uptake of water which further protects the wood from fungal attack. Diacrylate, dimethacrylate, and dihydroxyl functional PEG of M(w) 550-575, of concentrations 0, 30, 60, and 100 wt % in water, were vacuum pressure impregnated into Scots Pine blocks of 15 × 25 × 50 mm in an effort to bulk the cell wall. The samples were then irradiated and compared with nonirradiated samples. It was shown by IR, DSC that the acrylate polymers were fully cured to much higher conversions than can be reached with conventional methods. Leaching studies indicated a much lower amount of oligomer loss from the cured vinyl functional PEG chains in comparison to hydroxyl functional PEG indicating a high degree of fastening of the polymer in the wood. The Brinell hardness indicated a significant increase in hardness to hardwood levels in the modified samples compared to the samples of hydroxyl functional PEG and uncured vinyl PEG samples, which actually became softer than the untreated Scots Pine. By monitoring the dimensions of the sample it was found by weight percent gain calculations (WPG %) that water helps to swell the wood structure and allow better access of the oligomers into the cell wall. Further, the cure shrinkage of the wood samples demonstrated infiltration of the oligomers into the cell wall as this was not observed for methyl methacrylate which is well-documented to remain in the lumen. However, dimensional stability of the vinyl polymer modified blocks when placed in water was not observed to the same extent as PEG.     

Hyperendemicity associated with increased dengue burden

Over 105 million dengue infections are estimated to occur annually. Understanding the disease dynamics of dengue is often difficult due to multiple strains circulating within a population. Interactions between dengue serotype dynamics may result in complex cross-immunity dynamics at the population level and create difficulties in terms of formulating intervention strategies for the disease. In this study, a nationally representative 16-year time series with over 43 000 serotyped dengue infections was used to infer the long-run effects of between and within strain interactions and their impacts on past outbreaks. We used a novel identification strategy incorporating sign-identified Bayesian vector autoregressions, using structural impulse responses, historical decompositions and counterfactual analysis to conduct inference on dengue dynamics post-estimation. We found that on the population level: (i) across-serotype interactions on the population level were highly persistent, with a one time increase in any other serotype associated with long run decreases in the serotype of interest (range: 0.5–2.5 years) and (ii) over 38.7% of dengue cases of any serotype were associated with across-serotype interactions. The findings in this paper will substantially impact public health policy interventions with respect to dengue.     

Active and passive tobacco smoke exposure: a comparison of maternal and child hair cotinine levels.

The objective of this study was to compare tobacco smoke exposure in mothers and their healthy children less than 3 years old using hair cotinine (HC) levels as an objective long-term measure of exposure. Hair samples were obtained from mother/child pairs recruited from the Columbus Children's Hospital Primary Care Center, and were analyzed by radioimmunoassay to compare HC levels. Mothers were both self-reported smokers and nonsmokers. Contributing and confounding variables were assessed based on questionnaires completed by participants. Exclusion criteria for children were prematurity and presence of chronic cardiopulmonary disease. Hair samples and questionnaires were obtained from 104 mother/child pairs. Child and maternal HC levels were correlated for both self-reported maternal smokers (R2 = .13, p < .013) and self-reported maternal nonsmokers (R2 = .54, p < 001). Child HC levels were higher than maternal HC levels (1.18 ng/mg vs. .78 ng/mg, p < .001). Children of nonsmokers had higher HC levels than their mothers (.77 ng/mg vs. .35 ng/mg, p < .001), while HC levels of smokers and their children were no different (1.91 ng/mg vs. 1.92 ng/mg, p = .978). The relationship between child and maternal HC did not differ by child age, gender, or race. In conclusion, environmental tobacco smoke exposure in young children as reflected by HC is higher than expected based on prior studies of biomarkers and passive tobacco smoke exposure in adult nonsmokers.     

Fundamental examination of nanoparticle heating kinetics upon near infrared (NIR) irradiation

Near infrared (NIR) light, which spans wavelengths from ~700-1100 nm holds particular promise in bionanotechnology-enabled applications because both NIR light and nanoparticles (NPs) have the potential for remote activation leading to exquisite localization and targeting scenarios. In this study, aqueous solutions of carbon and metal-based NPs (carbon black, single-walled carbon nanotubes, silver nanoparticles and copper nanoparticles) were exposed to continuous NIR laser (λ = 1064 nm) irradiation at powers of 2.2W and 4.5W. The differential heating of bulk aqueous suspension of NPs with varying physicochemical properties revealed maximum temperatures of 67 °C with visible evidence of condensation and bubble formation. The basis of the NP heating is due to the strong intrinsic optical absorbance in the NIR spectral window and the transduction of this NIR photon energy into thermal energy. In this regard, UV-vis measurements can accurately predict NP heating kinetics prior to NIR irradiation. Further, a uniform thermodynamic heating model demonstrates close agreement with the experimental data for the low NIR-absorbing NPs. However, the uniform thermodynamic heating model used in this study does not accurately portray the energy release upon localized NP heating because of bubble formation for the highly absorbing NPs. Therefore, this study reveals the differential heating kinetics of NPs excited with NIR with implications in the development of novel NIR-NP-based systems.     

Infants' ability to parse continuous actions.

In a series of 3 experiments, the authors examined 6- and 8-month-old infants' capacities to detect target actions in a continuous action sequence. In Experiment 1, infants were habituated to 2 different target actions and subsequently were presented with 2 continuous action sequences that either included or did not include the familiar target actions. Infants looked significantly longer at the sequences that were novel. Experiment 2 presented the habituation and test trials in the reverse order. The results showed that infants habituated to the sequence still showed reliable evidence of recognizing the target action during the test trials. Experiment 3 was comparable to Experiment 2, except it tested whether infants could detect a different event segment, namely the transitions between events. The results showed that infants did not discriminate between test trials suggesting that transitions between events are not as easy for infants to recognize. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Engineered Fibrillar Fibronectin Networks as Three‐Dimensional Tissue Scaffolds

Extracellular matrix (ECM) proteins, and most prominently, fibronectin (Fn), are routinely used in the form of adsorbed pre‐coatings in an attempt to create a cell‐supporting environment in both two‐ and three‐dimensional cell culture systems. However, these protein coatings are typically deposited in a form which is structurally and functionally distinct from the ECM‐constituting fibrillar protein networks naturally deposited by cells. Here, the cell‐free and scalable synthesis of freely suspended and mechanically robust three‐dimensional (3D) networks of fibrillar fibronectin (fFn) supported by tessellated polymer scaffolds is reported. Hydrodynamically induced Fn fibrillogenesis at the three‐phase contact line between air, an Fn solution, and a tessellated scaffold microstructure yields extended protein networks. Importantly, engineered fFn networks promote cell invasion and proliferation, enable in vitro expansion of primary cancer cells, and induce an epithelial‐to‐mesenchymal transition in cancer cells. Engineered fFn networks support the formation of multicellular cancer structures cells from plural effusions of cancer patients. With further work, engineered fFn networks can have a transformative impact on fundamental cell studies, precision medicine, pharmaceutical testing, and pre‐clinical diagnostics.     

Memory accessibility and association of alcohol use and its positive outcomes.

Theoretical predictions involving memory associations between alcohol use and its positive outcomes were examined. In 2 preliminary studies, the availability from memory of outcomes from drinking was investigated. In subsequent studies, a measurement paradigm was used that decreased the accessibility of the association between drinking behavior and positive outcomes so that individual differences in drinking frequency might predict the accessibility of memory responses. In a final study, this paradigm was refined further by manipulating various types of alcohol-related cues. The results converge on a class of theory of memory association in which repeated drinking experiences influence the accessibility of thoughts about alcohol use and its most normatively frequent outcomes. The increased association of this behavior and its outcomes in memory has important implications for the cognitive mediation of alcohol use and abuse. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Self-generated drug outcomes in high-risk adolescents.

The perceived outcomes of drug use were studied in a sample of high-risk adolescents. Participants' self-generated responses provided the actual words they used to describe drug outcomes as well as associative frequency norms valuable for future research. The authors also compared outcomes in terms of class of outcome (positive vs. negative) and class of drug (alcohol, marijuana, cigarettes, cocaine, speed, and LSD). Although the studied drugs have divergent pharmacological effects. participants self-generated some of the same outcomes (e.g., relaxation) across some of the drugs. In addition, outcomes self-generated as positive outcomes were very rarely also self-generated as negative outcomes. Finally, regressions revealed that self-generated responses were not predicted by ethnicity, gender, or previous drug use. Many drug use outcomes thus appeared to be available in memory regardless of previous drug use or other characteristics. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Memory association and ambiguous cues in models of alcohol and marijuana use.

In parallel models of memory and expectancy theory, memory associations between drug-related cues and drug use may have motivational implications. This study examined whether these types of memory associations can be considered both a product and a predictor of alcohol and marijuana use consistent with a motivational model of drug use memory association. Results from a diverse college sample indicated that participants' memory associations to ambiguous cues were significantly related to alcohol and marijuana use independent of a number of possible correlates of these variables (e.g., family history of alcohol use acculturation and friends' drug use). The analytical models showed that these relationships held whether memory association was analyzed as a predictor or as a product of drug use. The results were consistent with the view that memory association is related to drug use through a parallel memory process akin to R. C. Bolles's (1972) concept of expectancy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)