Tunable temperature‐ and shear‐responsive hydrogels based on poly(alkyl glycidyl ether)s

We describe the synthesis, characterization and direct‐write 3D printing of triblock copolymer hydrogels that have a tunable response to temperature and shear stress. In aqueous solutions, these polymers utilize the temperature‐dependent self‐association of poly(alkyl glycidyl ether) ‘A’ blocks and a central poly(ethylene oxide) segment to create a physically crosslinked three‐dimensional network. The temperature response of these hydrogels was dependent upon composition, chain length and concentration of the ‘A’ block in the copolymer. Rheological experiments confirmed the existence of sol–gel transitions and the shear‐thinning behavior of the hydrogels. The temperature‐ and shear‐responsive properties enabled direct‐write 3D printing of complex objects with high fidelity. Hydrogel cytocompatibility was also confirmed by incorporating HeLa cells into select hydrogels resulting in high viabilities over 24 h. The tunable temperature response and innate shear‐thinning properties of these hydrogels, coupled with encouraging cell viability results, present an attractive opportunity for additive manufacturing and tissue engineering applications. © 2018 Society of Chemical Industry     

The influence of porous silicon on axonal outgrowth in vitro.

xonal outgrowth on smooth and porous silicon surfaces was studied in organ culture. The pore size of the silicon substrata varied between 100 and 1500 nm. We found that axons preferred to grow and elongate on porous silicon surfaces only when pores of (150-500 nm) are available.     

Carotenoid composition and antioxidant activity of the raw and boiled fruit mesocarp of six varieties of Bactris gasipaes

Total carotenoid content and composition of carotenoids of six varieties of Bactris gasipaes were determined by spectrophotometry and HPLC, with photodiode array detector. Significant differences in total carotenoid content (1.1 to 22.3 mg/100g) were detected among these varieties. Boiling the fruits for 30 minutes did not affect total carotenoid content, but did change the amount of some specific carotenoids, mainly by the production of Z-isomers. Peach palm varieties had the same carotenoids, but in different proportions, presenting mainly, all E-beta-carotene (26.2% to 47.9%), Z-gamma-carotene (18.2% to 34.3%) and Z-lycopene (10.2% to 26.8%). When antioxidant activity was evaluated using DPPH, it was observed that the variety with higher percentages of beta-carotene (54.1%) presented the higher activity. This is one of the first reports in carotenoid content and antioxidant activity in well typified varieties of Bactris gasipaes, whose results could have a positive impact in the consumption of certain peach palm varieties.     

Antimicrobial peptides and their superior fluorinated analogues: structure-activity relationships as revealed by NMR spectroscopy and MD calculations

The conformations of two synthetic pentapeptides with antimicrobial activity and their 4-fluorophenylalanine (Pff)-containing analogues (ArXArXAr-NH(2); Ar=Phe, Pff; X=Lys, Arg) have been studied. NMR experiments carried out both in aqueous fluoroalcohol solutions and SDS micelles permitted their interactions with membrane-like environments to be explored. WaterLOGSY experiments and Mn(2+)-based paramagnetic probes were also applied to assess their orientations with respect to the SDS micelles. In addition, pulse-field gradient (PFG) diffusion NMR spectroscopy studies were conducted, under different experimental conditions (i.e., concentration, temperature) to characterize the possible changes in the peptides' aggregation states as a putative critical factor for their antimicrobial activity. Finally, molecular dynamics simulations on a variety of conformations showed the intrinsic flexibility of these peptides in both aqueous solutions and membrane-mimetic systems.     

Development of a stakeholder identification and analysis method for human factors integration in work system design interventions – Change Agent Infrastructure

In any work system design intervention—for example, a physical workplace re-design, a work process change, or an equipment upgrade—it is often emphasized how important it is to involve stakeholders in the process of analysis and design, to gain their perspectives as input to the development, and ensure their future acceptance of the solution. While the users of an artifact or workplace are most often regarded as being the most important stakeholders in a design intervention, in a work-system context there may be additional influential stakeholders who influence and negotiate the design intervention's outcomes, resource allocation, requirements, and implementation. Literature shows that it is uncommon for empirical ergonomics and human factors (EHF) research to apply and report the use of any structured stakeholder identification method at all, leading to ad-hoc selections of whom to consider important. Conversely, other research fields offer a plethora of stakeholder identification and analysis methods, few of which seem to have been adopted in the EHF context. This article presents the development of a structured method for identification, classification, and qualitative analysis of stakeholders in EHF-related work system design intervention. It describes the method's EHF-related theoretical underpinnings, lessons learned from four use cases, and the incremental development of the method that has resulted in the current method procedure and visualization aids. The method, called Change Agent Infrastructure (abbreviated CHAI), has a mainly macroergonomic purpose, set on increasing the understanding of sociotechnical interactions that create the conditions for work system design intervention, and facilitating participative efforts.     

An Elevator Button Recognition Method Combining YOLOv5 and OCR

Fast recognition of elevator buttons is a key step for service robots to ride elevators automatically. Although there are some studies in this field, none of them can achieve real-time application due to problems such as recognition speed and algorithm complexity. Elevator button recognition is a comprehensive problem. Not only does it need to detect the position of multiple buttons at the same time, but also needs to accurately identify the characters on each button. The latest version 5 of you only look once algorithm (YOLOv5) has the fastest reasoning speed and can be used for detecting multiple objects in real-time. The advantages of YOLOv5 make it an ideal choice for detecting the position of multiple buttons in an elevator, but it’s not good at specific word recognition. Optical character recognition (OCR) is a well-known technique for character recognition. This paper innovatively improved the YOLOv5 network, integrated OCR technology, and applied them to the elevator button recognition process. First, we changed the detection scale in the YOLOv5 network and only maintained the detection scales of 40 * 40 and 80 * 80, thus improving the overall object detection speed. Then, we put a modified OCR branch after the YOLOv5 network to identify the numbers on the buttons. Finally, we verified this method on different datasets and compared it with other typical methods. The results show that the average recall and precision of this method are 81.2% and 92.4%. Compared with others, the accuracy of this method has reached a very high level, but the recognition speed has reached 0.056 s, which is far higher than other methods.     

Efficient GPU-based parallelization of solvation calculation for the blind docking problem

The Journal of Supercomputing - Molecular docking techniques are widely used in computational drug discovery. Most of these techniques simulate the way that a ligand interacts with a protein target...     

Solving constrained optimization problems with a hybrid particle swarm optimization algorithm

This article presents a particle swarm optimization algorithm for solving general constrained optimization problems. The proposed approach introduces different methods to update the particle's information, as well as the use of a double population and a special shake mechanism designed to avoid premature convergence. It also incorporates a simple constraint-handling technique. Twenty-four constrained optimization problems commonly adopted in the evolutionary optimization literature, as well as some structural optimization problems are adopted to validate the proposed approach. The results obtained by the proposed approach are compared with respect to those generated by algorithms representative of the state of the art in the area.