Mechanical Efficiency Investigation of an Ankle-Assisted Robot for Human Walking With a Backpack-Load.

The purpose of this work is to investigate the efficiency of wearable assistive devices under different load-carriage walking. We designed an experimental platform with a lightweight ankle-assisted robot. Eight subjects were tested in three experimental conditions: free walk with load (FWL), power-off with load (POFL), and power-on with load for different levels of force at a walking speed of 3.6 km/h. We recorded the metabolic expenditure and kinematics of the subjects under three levels of load-carried (10%, 20%, and 30% of body mass). We define the critical force, where at a certain load, the robot inputs a certain force to the human body, and with the assistance of this force, the positive effect of the robot on the human body exactly compensates for the negative effect. The critical forces from the fit of the assistive force and metabolic cost curves were 130 N, 160 N, and 215 N at three different load levels. The intrinsic weight of our device increases mechanical work at the ankle as the load weight rises with 2.08 J, 2.43 J, and 2.73 J for one leg during a gait cycle. With weight bearing increasing, the ratio of the mechanical work input by the robot to the mechanical work output by the weight of the device decreases (from 0.904 to 0.717 and 0.513), verifying that the walking assistance efficiency of such devices decreases as the weight rises.

Modular synthesis of α-aryl ß-perfluoroalkyl ketones via N-heterocyclic carbene catalysis.

A new general de novo synthesis of pharmaceutically important α-aryl ß-perfluoroalkyl ketones has been disclosed. Compared with trifluoromethylation-initiated radical 1,2-aryl migration of α,α-diaryl allylic alcohols, this protocol employs a new strategy of biomimetic carbene catalysis to assemble alkene, aldehyde and perfluoroalkyl reagents, providing access to products with excellent flexibility of the aryl unit and perfluoroalkyl group. This method also demonstrates excellent functional group compatibility, including some Grignard reagent sensitive groups.

Design, synthesis and biological evaluation of 3-(4-halophenyl)-3-oxopropanal and their derivatives as novel antibacterial agents.

In continuing our program aimed to search for potent drugs for bacterial infections, a series of 3-(4-halophenyl)-3-oxopropanal and their derivatives were designed, synthesized and their antibacterial activities in vitro against both Gram-positive bacteria Staphylococcus aureus and Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa were evaluated. Compounds 7, 8, 13-16, 21 and 22 had moderate antibacterial activities against Staphylococcus aureus (minimal inhibitory concentration (MIC) <16 microg/ml), suggesting that the introduction of mono-methoxyamine or ethoxyamine moiety might play an important role in determining the potent antibacterial activities. Furthermore, the antibacterial activities of select compounds 7, 15 and 16 against the clinically important pathogenic bacteria-methicillin-resistant Staphylococcus aureus (MRSA) were also investigated. Results showed that these compounds exhibited more potent activities than the well-known antibacterial agents Houttuynin and Levofloxacin.