An accurate and precise 3 μL blood collection and dispensing system is presented for the preparation of dried blood spot (DBS) samples. Using end-to-end glass capillaries in conjugation with pre-punched DBS pads, a blood micro collection system was developed to eliminate the haematocrit dispersion, widely associated with DBS technology, while providing better levels of accuracy and precision during sample preparation. This methodology is compared to traditional micro-volume blood collection systems, such as a pipette and a digitally controlled analytical syringe. Results showed that % of recovery for the capillary methodology was closer to 100% across the three haematocrit (HCT) levels tested and when prepared by two users (98 to 100% for capillaries, 78 to 104% for pipette and 93 to 97% for digital syringe) attesting a higher accuracy. Additionally, by taking advantage of the capillary action mechanism to collect and dispense autonomously the desired volume of blood onto the DBS pad, coefficients of variation between two individuals were significantly lower than with standard methodologies (capillaries-0.05 to 0.77%, pipette-12.71 to 18.53% and digital syringe-0.72 to 1.77%). This alternate aspiration and dispensing methodology could be used by different users without compromising accuracy or precision when handling low volumes of blood during the pre-analytical steps. Graphical abstract Comparison of novel capillary dispensing methodology for dried blood spot sample preparation with pipette and digital syringe methodologies through accuracy and precision measurements of caffeine.

ABSTRACT:The influences of the type and concentration of ␣-olefin (1-hexene, 1-octene, 1-decene, 1-octadecene, 4-methyl-1-pentene) on the mechanical behavior and crystallinity degree of some ethylene/␣-olefin copolymers obtained by metallocene catalysts were studied by means of stress/strain experiments. The crystallinity degree of these copolymers has been determined by X-ray measurements. It has been observed that the copolymers show less resistance to strain as the comonomer content increases and the crystallinity decreases. Most of the studied copolymers exhibit a significant increase in the crystallinity level after the stress/strain experiments.

A styrene-butadiene-styrene triblock copolymer (SBS) was functionalized with glycidyl methacrylate (GMA). Grafting reactions were carried out in an internal mixer at 170°C, using dicumyl peroxide (DCP) as an initiator. The effect of three variables, % GMA, % DCP, and reaction time, on grafting were studied using a factorial design to analyze the experimental data. GMA was grafted onto SBS and its incorporation increased with the % GMA added. The factors levels studied indicated that was an optimum % DCP point about 0.1% w/w to achieve the best incorporation and conversion values.

Maleic anhydride functionalized PP was prepared in a melt‐mixer according to a factorial design. Two levels of maleic anhydride concentration (MA), dicumyl peroxide concentration (DCP), reaction time, and temperature were employed. The isolated and interaction effects of these variables on the degree of functionalization and molecular weights were analyzed. The products were characterized by Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), titration, and torque measures. The reaction time showed no appreciable effect within the studied range (10 to 20 minutes); however, the other three factors showed significant main effects. MA and temperature presented an important interaction effect on the degree of functionalization and molecular weights. The highest degrees of functionalization were found to be related to the smallest molecular weights.

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Misturas de Polietileno de Baixa Densidade (PEBD) com diferentes tipos e proporções de Polietilenos Lineares de Baixa Densidade (PELBD) foram preparadas em extrusora de rosca simples e dupla a fim de verificar a influência destes últimos na viscosidade e cristalinidade das misturas. As misturas de PEBD com PELBD foram avaliadas através de reometria capilar e calorimetria (DSC). As misturas de PEBD com PELBD com comonômero de 1-buteno e de 1-octeno, preparadas em extrusora de rosca simples ou dupla, não apresentaram diferenças no perfil das curvas reológicas. Entretanto, as misturas de PEBD com PELBD com comonômero 1-hexeno apresentaram diferenças nas curvas de viscosidade. Verificou-se que a adição de PELBD na mistura modifica significativamente a viscosidade principalmente em altas taxas de cisalhamento. Pela avaliação das curvas de fusão, observou-se que o aumento da concentração de PELBD nas misturas provoca uma variação no comportamento térmico das mesmas com o conseqüente alargamento da faixa de fusão.

To study the relationship among relaxation peaks observed in dynamic mechanical experiments and the structure of poly(ethylene-co-vinyl acetate) (EVA), EVA copolymers with different substitution in the carbonyl group were synthesized. EVA was hydrolyzed to obtain poly (ethylene-co-vinyl alcohol) and was subsequently reacted with formic, hexanoic, and octanoic acids. The copolymers synthesized were characterized by infrared spectroscopy. Analysis of the DMA spectra of the copolymers showed that their relaxation behavior depends on the vinyl acetate concentration. The ␣-and ␤-transitions were observed in EVA copolymers with 8 and 18 wt % of functional groups, and the relationship among relaxation process with the structure of polymer was investigated.