DNA transport in hierarchically-structured colloidal-nanoparticle porous-wall nanochannels

We report a simple approach to the formation of 3D colloidal nanoparticle structures incorporating enclosed mesoscopic structures through a simple process of spin-coating-driven directed self-assembly onto lithographically defined polymer templates. Removal of the buried polymer patterns by high temperature calcination results in the formation of hierarchically enclosed channels, continuous networks, isolated cavities, and multilayered structures with high stability and environmental resistance. These channels are used to investigate the transport of DNA molecules in constrained geometries.     

Current rectification by mediating electroactive polymers

In this work we briefly review the theoretical basis for the electrochemical rectification in mediated redox reactions at redox polymer modified electrodes. Electrochemical rectification may have two distinct origins. It is either caused by a slow kinetics of the reaction between the external redox couple and the mediator or it is originated by a slow electronic transport within the film under an unfavorable thermodynamic condition. We show experimental results for the redox mediation reaction of poly(o-aminophenol) (POAP) on the Fe^2+/3+ and on the Fe(CN)₆^3−/4− redox couples in solution that prove the proposed mechanisms of electrochemical rectification.     

Isolation,identification and development of culture medium in the production of Chlorella vulgaris

Microalgae have gained importance as a potential component of conventional food. The aim of the present study was to study the behaviour of the microalga Chlorella vulgaris in relation to the different carbon and nitrogen sources and to improve a culture medium in terms of glucose, urea, manganese chloride and sodium nitrate concentrations. In the investigation of the best source of carbon and nitrogen, it was observed that 1.14 mg L^?1 of glucose and 8.32 mg L^?1 of urea stood out with the production of 0.823 g L^?1 of dry biomass and yield of 52 mg L^?1 day^?1. The best growth rate and specific yield were achieved at the central points for all salts.     

The effect of diffusion gradient direction number on corticospinal tractography in the human brain: an along-tract analysis

Objectives

We evaluated diffusion imaging measures of the corticospinal tract obtained with a probabilistic tractography algorithm applied to data of two acquisition protocols based on different numbers of diffusion gradient directions (NDGDs).

Materials and methods

The corticospinal tracts (CST) of 18 healthy subjects were delineated using 22 and 66-NDGD data. An along-tract analysis of diffusion metrics was performed to detect possible local differences due to NDGD.

Results

FA values at 22-NDGD showed an increase along the central portion of the CST. The mean of partial volume fraction of the orientation of the second fiber (f2) was higher at 66-NDGD bilaterally, because for 66-NDGD data the algorithm more readily detects dominant fiber directions beyond the first, thus the increase in FA at 22-NDGD is due to a substantially reduced detection of crossing fiber volume. However, the good spatial correlation between the tracts drawn at 22 and 66 NDGD shows that the extent of the tract can be successfully defined even at lower NDGD.

Conclusions

Given the spatial tract localization obtained even at 22-NDGD, local analysis of CST can be performed using a NDGD compatible with clinical protocols. The probabilistic approach was particularly powerful in evaluating crossing fibers when present.

     

An improved gravimetric method applied to co-processing of polyethylene terephtalate and petroleum blend using HY zeolite as a catalyst

The co-processing of petroleum and polyethylene terephthalate (PET) was carried out in the presence and absence of a catalyst in an open vessel batch reactor at temperatures of 200, 300, 400, and 500 °C, which corresponds to temperatures of distillation and cracking. The catalyst used was the acidic HY zeolite, which is widely used in petroleum refining. The catalytic co-processing was carried out with the PET–oil charge, at a mass ratio of 1:1, containing 10% of HY zeolite. The conversion degree was measured by knowing the initial sample mass and amount of degraded material for each temperature and reaction time, using an improved gravimetric method consisting of a precision balance and an oven with a heating rate controller. The conversion values obtained were compared for petroleum and PET samples with and without the zeolite catalyst. At temperatures of 200 and 300 °C, the PET showed low conversions, about 5–10%. However, for the catalytic co-processing of PET–oil/HY at these same temperatures, an increase in conversion to about 25–30% was observed. At temperatures of 400 and 500 °C, conversions above 90% were obtained for the two samples, with a subsequent reduction in the activation energy, from 76 kJ mol^?1 (PET) to 56 kJ mol^?1 (PET–oil/HY). The decrease in the activation energy proved the efficiency of the HY zeolite and the synergistic effect when PET was blended to the oil for the catalytic co-processing, proving to be a viable alternative for the chemical recycling of PET in the petroleum industry.     

Biomolecular papain thin films growth by laser techniques

Papain thin films were synthesised by matrix assisted and conventional pulsed laser deposition (PLD) techniques. The targets submitted to laser radiation consisted on a frozen composite obtained by dissolving the biomaterials in distilled water. For the deposition of the thin films by conventional PLD pressed biomaterial powder targets were submitted to laser irradiation. An UV KrF* excimer laser source was used in the experiments at 0.5 J/cm² incident fluence value, diminished one order of magnitude as compared to irradiation of inorganic materials. The surface morphology of the obtained thin films was studied by atomic force profilometry and atomic force microscopy. The investigations showed that the growth mode and surface quality of the deposited biomaterial thin films is strongly influenced by the target preparation procedure.     

Perception, attitudes and beliefs, and openness to change: implications for older driver education

With a rapidly aging population, strategies for improving driver safety are beginning to emerge that focus on changing driving behaviors and knowledge. We examined the perceptions of risk, beliefs and attitudes, and openness to change of 86 older participants voluntarily attending a driver education program. It appeared that most people attending these sessions were not necessarily concerned about their own driving, safety or abilities, but were interested in maintaining mobility. They were conservative and reasonably consistent in their attitudes toward traffic regulations and safe driving practices. Some gender differences emerged with more men than women being resistant to changing their driving habits, more men than women reporting that they drive after consuming alcohol and more women than men identifying a role for their families in decision-making regarding driving cessation. This suggests that educational material may need to be targeted differently for men and women. It is anticipated that psychosocial factors related to driving such as driver perception, beliefs and openness to change will be useful for maximizing the fit between education program content and outcomes.     

The effect of prior ferrite formation on bainite and martensite transformation kinetics in advanced high-strength steels

Most advanced high-strength steel products contain complex phases, including ferrite, bainite and martensite, which form successively during elaboration. It is essential to understand the effect of prior ferrite transformation on the subsequent bainite and martensite transformation kinetics to achieve precise control of the final microstructure. Nevertheless, the effect of the interface between the prior formed ferrite and the residual austenite (α/γ), together with the related chemical heterogeneity at the interface, on the subsequent phase transformations has been studied only rarely, and remains unclear. This study pays particular attention to the effect of the α/γ interface and its related concentration gradients on bainite and martensite transformation. It is shown that the interface and its related concentration gradients can play a very significant role on the subsequent bainite or martensite transformation kinetics: it retards bainite transformation whereas it accelerates martensite transformation. It is revealed from microprobe wavelength-dispersive spectrometry analysis and model calculations that there are both manganese and carbon gradients in front of the α/γ interface at the end of the ferrite transformation holding. The subsequent bainite transformation kinetics is controlled by the competition between the acceleration effect of the interface boundary itself and the retardation effect of the higher alloying concentration near the interface. Martensite transformation should initiate at the pre-existing dislocations in the center of the residual austenite grains, where the C and Mn contents are the lowest. A simple martensite transformation kinetics model taking into account C heterogeneity is proposed that can describe well the martensite transformation kinetics following the prior ferrite transformation.