Effect of stereoisomerism of poly(lactic acid) during neural guide conduit membrane synthesis

Poly(lactic acid) membranes are being developed as biomaterials for several purposes such as artificial implants for peripheral nerve injury, also known as neural guide conduits (NGC). These membranes need to meet standards of mechanical, degradability, and permeability properties, besides dimensional and structural requirements. Among the stereoisomers of polylactides, poly(l ‐lactic acid), and poly(d ,l ‐lactic acid) are the most used as biomaterials, having significant differences in solubility, crystallinity thermal, and mechanical properties. In this work, PLLA and PDLLA were compared for hollow fiber membrane synthesis by liquid induced phase separation. PLLA samples presented 18% of crystallinity, while PDLLA is amorphous. PDLLA and PLLA polymer solutions on N‐methyl‐pyrrolidone presented values of 3428 and 320.2 cP, respectively. In immersion of PLA‐NMP solutions in water, PLLA solution presented instantaneous demixing, while PDLLA showed a 28 s delay on precipitation. The PLLA–NMP–water has a larger demixing region compared to PDLLA–NMP–water system. Hollow fibers of both polymers presented closed external surface with finger‐like macropores morphology in their cross‐sections. PDLLA presented typical liquid–liquid demixing pores while PLLA presented spherulitical crystalline solid–liquid separation structures, which deeply compromised its mechanical properties. PDLLA presented as a good candidate for hollow fiber NGC material, as presented good mechanical resistance in tensile and suture simulating tests. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46190.     

Production,nutrient cycling and soil compaction to grazing of grass companion cropping with corn and soybean

Agricultural management systems are needed to simultaneously enhance production, promote plant diversity, improve nutrient cycling and reduce soil compaction. We investigated the effects of intercropped forage grass on production of corn (Zea mays L.) harvested for silage at 0.20 and 0.45 m height in the summer, as well as on production of subsequent forage, soybean [Glycine max (L.) Merr.] harvested for silage, nutrient cycling and soil responses on a Typic Haplorthox in Botucatu, São Paulo State, Brazil. Palisade grass cv. BRS Piatã [Urochloa brizantha cv. BRS Piatã] was the introduced companion crop with corn (Years 1 and 2), while signal grass [Urochloa decumbens cv. Basilisk] was the residual weedy species in comparison. Guineagrass cv. Aruãna [Megathyrsus maximus cv. Aruãna] was the introduced companion crop with soybean (Year 3), with only a residual effect of crop systems from the previous two years. After the corn silage harvest, pasture was grazed by lambs in winter/spring using a semi-feedlot system. When cut at 0.45 m compared with 0.20 m height, corn intercropped with palisade grass had greater leaf nutrient concentration, improved agronomic characteristics, forage mass of pasture for grazing by lambs, greater surface mulch produced, and greater quantity of N, P and K returned to soil. Greater soil organic matter, P, K and Mg concentration, and base saturation in the surface soil depth and lower soil penetration resistance at all depths occurred at 0.45 m than at 0.20 m corn silage cutting height intercropped with palisade grass. Analyzing the system as a whole, harvesting corn silage crop with palisade grass intercrop at 0.45 m height was the most viable option in this integrated crop-livestock system.     

意大利高层建筑应急处理的新观点

为了促进高层办公建筑安全的发展，介绍了建筑物的结构和结构特点及应急处理所采取的措施。Pirellil摩天大楼事故提醒我们，需要考虑大厦的整体安全，尤其是应对恐怖分子袭击的防御系统。     

Sleep-related car crashes: risk perception and decision-making processes in young drivers

The aim of the present study is to analyse factors affecting worries, coping strategies and decisions of young drivers regarding the risk of sleep-related car crashes. Furthermore, the study also analyses whether framing the same information about sleepiness in two different linguistic forms influences: (1) the evaluation of the level of risk associated to a specific level of drowsiness (Attribute Framing problem); (2) the willingness to enact strategies to "prevent" sleepiness before night-time driving (Goal Framing problem); (3) the choice between two different ways, both of equal expected efficacy, of lowering drowsiness (Risky decision-making Framing problem). Six hundred and ninety-five young drivers [(57.6% females, 42.4% males); mean age 20.85 years (S.D.=1.2)] answered questions on drive risk perception and sleepiness, on nocturnal driving experience and on the strategies to deal with driver sleepiness, responding to one of the two different versions of the framed problems. A sub-sample of 130 participants completed the framed problems in both versions. The results show that experiences of sleep attacks and nocturnal driving frequency in the past 6 months affect both risk perception and the preventive strategies adopted. Furthermore, the manipulation on two out of the three problems (attribute and risky decision-making frames) significantly affected the respondents' evaluation.     

Phase constraint for the waves diffracted by lossless symmetrical gratings at Littrow mount

The energy conservation of grating diffraction is analyzed in a particular condition of incidence in which two incident waves reach a symmetrical grating from the two sides of the grating normal at the first-order Littrow mounting. In such a situation the incident waves generate an interference pattern with the same period as the grating. Thus in each direction of diffraction, interference occurs between two consecutive diffractive orders of the symmetrical incident waves. By applying only energy conservation and the geometrical symmetry of the grating profile to this problem it is possible to establish a general constraint for the phases and amplitudes of the diffracted orders of the same incident wave. Experimental and theoretical results are presented confirming the obtained relations.     

Microstructure and corrosion behaviour of pulsed plasma-nitrided AISI H13 tool steel

The effect of pulsed plasma nitriding temperature and time on the pitting corrosion behaviour of AISI H13 tool steel in 0.9% NaCl solutions was investigated by cyclic polarization. The pitting potential (E_pit) was found to be dependent on the composition, microstructure and morphology of the surface layers, whose properties were determined by X-ray diffraction and scanning electron microscopy techniques. The best corrosion protection was observed for samples nitrided at 480 °C and 520 °C. Under such experimental conditions the E_pit-values shifted up to 1.25 V in the positive direction.     

Personality and attitudes as predictors of risky driving among older drivers

Although there are several studies on the effects of personality and attitudes on risky driving among young drivers, related research in older drivers is scarce. The present study assessed a model of personality-attitudes-risky driving in a large sample of active older drivers. A cross-sectional design was used, and structured and anonymous questionnaires were completed by 485 older Italian drivers (Mean age = 68.1, SD = 6.2, 61.2% males). The measures included personality traits, attitudes toward traffic safety, risky driving (errors, lapses, and traffic violations), and self-reported crash involvement and number of issued traffic tickets in the last 12 months. Structural equation modeling showed that personality traits predicted both directly and indirectly traffic violations, errors, and lapses. More positive attitudes toward traffic safety negatively predicted risky driving. In turn, risky driving was positively related to self-reported crash involvement and higher number of issued traffic tickets. Our findings suggest that theoretical models developed to account for risky driving of younger drivers may also apply in the older drivers, and accordingly be used to inform safe driving interventions for this age group.