Forgotten monomers: access to α‐modified N‐vinylpyrrolidone polymers via C‐alkylation

Alkylation of N‐vinylpyrrolidone using lithium diisopropylamide and bis(2‐bromoethyl) ether was carried out to obtain 3‐(2‐(2‐bromoethoxy)ethyl)‐1‐vinyl‐2‐pyrrolidone ( 2 ). The derivative 2 represents a versatile starting molecule for further modification via nucleophilic displacement yielding, for example, the bicyclic 2‐vinyl‐8‐oxa‐2‐azaspiro[4.5]decan‐1‐one ( 4 ) or the ammonium salt 3‐diethoxy‐N,N′‐((dimethylbenzyl)ammonium bromide)‐1‐vinyl‐2‐pyrrolidone ( 10 ). Via free radical polymerization of 4 and 10 , the corresponding homopolymers were obtained. Copolymerization of 4 and 10 with N,N′‐diethylacrylamide yielded water‐soluble materials. The thermosensitive solubility of copolymers poly[(2‐vinyl‐8‐oxa‐2‐azaspiro[4.5]decan‐1‐one)‐co‐(N,N′‐diethylacrylamide)] and poly[(3‐diethoxy‐N,N′‐((dimethylbenzyl)ammonium bromide)‐1‐vinyl‐2‐pyrrolidone)‐co‐(N‐vinylpyrrolidone)] in water was investigated. © 2015 Society of Chemical Industry     

Analysis of electromigration phenomenon in thick-film and LTCC structures at elevated temperature

Studies on electromigration phenomenon in thick-film structures on alumina and LTCC substrates are presented in this paper. The effects of storage of Au and Ag electrode patterns in temperature range up to 300 °C under voltage bias were examined. The leakage characteristics of electrodes with 100 μm spacing at 50 V dc bias as a function of time and temperature are presented and analyzed. Scanning electron microscope (SEM) equipped with the energy-dispersive X-ray spectroscopy (EDX) detector was applied for determination of metal ions transport. Test structures with Au-based conductive material are much more resistant to electromigration than Ag-based layers.     

Microbial growth,communities and sensory characteristics of vacuum and modified atmosphere packaged lamb shoulders

Packaging fresh lamb in a vacuum (VAC) versus a 100% CO₂ modified atmosphere (MAP) may influence product shelf-life and the bacterial communities. While VAC is a common packing method and 100% CO₂ MAP is used in some countries, there is little information about how these different techniques affect the growth of spoilage bacteria and sensory attributes of lamb. The aim of this study was to assess changes in microbiological and organoleptic properties, and determine differences in microbial communities by terminal restriction fragment length polymorphism (TRFLP) and 454 pyrosequencing, in bone-in (BI) and bone-out (BO) MAP- and VAC-packed lamb shoulders stored at −0.3 °C over 12 wk. VAC and MAP lamb shoulders were acceptable in sensory test scores over 12 wk of storage at −0.3 °C, despite total viable count (TVC) and lactic acid bacteria (LAB) levels increasing to 8 log₁₀ CFU/cm² for VAC lamb and 4–6 log₁₀ CFU/cm² for MAP lamb. Similar to the sensory results, there were no significant differences in microbial communities between BI and BO product. However, types of bacteria were different between VAC and MAP packaging. Specifically, while VAC shoulder became dominated by Carnobacterium spp. in the middle of the storage period, the MAP shoulder microbial population remained similar from the start until later storage times.     

Effect of plasma treatment on the surface properties of polydimethylsiloxane

In this work, the analysis of the plasma modification of polydimethylsiloxane (PDMS) substrates was conducted. The influence of the modification onto the changes occurred within the geometrical structure and chemical composition of the surface was analyzed. Due to the study of the atomic force microscopy, it was possible to determine the relationships between the surface development and applied process parameters, defining the conditions facilitating to obtain isotropic or anisotropic orientations of wrinkles. A precise analysis of the chemical composition of the surface, executed before and after the modification processes, enabled to define the changes in their elementary composition. Moreover, the modification influence onto the changes of the contact angle and the surface free energy were also analyzed. So, based on the research it was stated that the increase of value of the surface free energy is proportional to the sp³ phase contents in the DLC coatings. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41635.     

Measuring errors and violations on the road: A bifactor modeling approach to the Driver Behavior Questionnaire

The Driver Behavior Questionnaire (DBQ) is a self-report measure of driving behavior that has been widely used over more than 20 years. Despite this wealth of evidence a number of questions remain, including understanding the correlation between its violations and errors sub-components, identifying how these components are related to crash involvement, and testing whether a DBQ based on a reduced number of items can be effective. We address these issues using a bifactor modeling approach to data drawn from the UK Cohort II longitudinal study of novice drivers. This dataset provides observations on 12,012 drivers with DBQ data collected at .5, 1, 2 and 3 years after passing their test. A bifactor model, including a general factor onto which all items loaded, and specific factors for ordinary violations, aggressive violations, slips and errors fitted the data better than correlated factors and second-order factor structures. A model based on only 12 items replicated this structure and produced factor scores that were highly correlated with the full model. The ordinary violations and general factor were significant independent predictors of crash involvement at 6 months after starting independent driving. The discussion considers the role of the general and specific factors in crash involvement.     

Liquid-liquid extraction of protease from cold-adapted yeast Rhodotorula mucilaginosa L7 using biocompatible and biodegradable aqueous two-phase systems

This work aimed to optimize the extraction of an extracellular protease produced by the cold-adapted yeast Rhodotorula mucilaginosa L7 using aqueous two-phase systems (ATPS) comprising polyethylene glycol (PEG) and sodium citrate or sodium tartrate. First, the biocompatibility of the phase forming agents was assessed. The results obtained with PEG-2000, PEG-4000, and PEG-6000 demonstrated that even at large PEG concentrations (32 wt%) the protease maintains its activity after 3 h of reaction, whereas an increase in salt concentration provokes a gradual decrease in protease stability. Subsequently, the partitioning of the protease in both types of ATPS was assessed, evaluating the effect of temperature, molecular weight, and concentration of PEG on protease purification, using two 2³-full factorial designs. The best partitioning conditions were obtained in PEG-6000/sodium tartrate-based ATPS, at 30ºC (with a yield of 81.09 ± 0.66% and a purification factor of 2.51 ± 0.03). Thus, considering the biodegradable characteristics of the system, the PEG/sodium tartrate ATPS is a viable and economic low-resolution step in protease purification, with a strong potential for future industrial application.     

trans Fatty Acids in Colostrum,Mature Milk and Diet of Lactating Adolescents

The purpose of this study was to investigate the trans fatty acids (TFA) content and distribution in colostrum, mature milk, and diet of adolescent mothers, after TFA declaration in food labels became mandatory in Brazil. Participants were healthy adolescents (n 54, 15–19 years, 1–90 days postpartum) practicing exclusive breastfeeding. Milk samples were collected 3 days after delivery (colostrum) and in the third month postpartum (mature milk) by hand expression. The fatty acid composition of the milk samples was determined by gas chromatography. TFA intake corresponded to 1.23 % of total energy value. Total 18:2 TFA accounted for less than 0.5 % of the energy intake. The amount of total 18:1 TFA (mean ± SEM) was 1.9 % ± 0.14 in colostrum and 1.5 % ± 0.2 in mature milk. The total content of n‐3 PUFA was inversely correlated with the total content of 18:1 TFA in colostrum. Both in colostrum and in mature milk, vaccenic acid (11t‐18:1) was found to be the most abundant 18:1 trans isomer, followed by elaidic acid (9t‐18:1), whereas rumenic acid (9c,11t‐18:2 CLA) was the predominant 18:2 trans isomer. In conclusion, the levels of TFA of industrial sources found in the mother's diet and breast milk (colostrum and mature milk) showed a decrease in relation to those observed in studies conducted prior to the TFA labeling resolution in Brazil. However, the current low intake levels of n‐3 LCPUFA and DHA content in the milk of lactating adolescents may be insufficient for supporting adequate neurological development of the infants.     

Structure–property relationship of sodium deoxycholate based poly(ester ether)urethane ionomers for biomedical applications

New sodium deoxycholate based poly(ester ether)urethane ionomers were prepared for the development of biomedical materials. A structure–property relationship in the tested biomaterials was established by cross‐examination of the dynamic mechanical and dielectric properties, attenuated total reflection–Fourier transform infrared investigation, thermogravimetric analysis, and surface morphology characterization. A stronger ionic interaction and solvation capacity of the ions and a higher ionic conductivity were manifested in the case of poly(ethylene oxide)‐rich segments than for poly(propylene oxide)‐rich segments in these polyurethane ionomers. The molecular and ionic interactions of the bile‐salt moiety with different polyether cosoft segments influenced chain packing and conformation, supramolecular organization, and the resulting surface morphological microstructures of the polyurethane biomembranes. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42921.