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Regulating the fluid flow in microfluidic devices enables a wide range of assay protocols for analytical applications. A programmable, photo-paper-based microfluidic device fabricated by using a method of cutting and laminating, followed by printing, is reported. The flow distance of fluid in the photo-paper-based channel was linearly proportional to time. By printing silver nanoparticle (AgNP) and poly[4,5-difluoro-2,2-bis(trifluoromethyl)-1,3-dioxole-co-tetrafluoroethylene] (PTFE) patterns on the surface of a photo-paper-based channel, we were able to either increase or decrease the fluid flow in the fabricated microfluidic devices, while maintaining the linearity in the flow distance-time relation. In comparison to the speed of fluid flow in a pristine channel, by using hydrophilic AgNP patterns, we were able to increase the speed in the channel by up to 15 times while we were able to slow the speed by a factor of 3 when using hydrophobic PTFE dots. We then further demonstrated a single-step protocol for detecting glucose and a multi-step protocol for detecting methyl paraoxon (MPO) with our methods in photo-paper-based microfluidic devices. This approach can lead to improved fluid handling techniques to achieve a wide range of complex, but programmable, assays without the need for any additional auxiliary devices for automated operation.

The transgalactosylase activity of β-galactosidase produces galacto-oligosaccharides (GOSs) with prebiotic effects similar to those of major oligosaccharides in human milk. β-Galactosidases from

A region suffering from an attack of a nerve agent requires not only a highly sorptive material but also a fast-acting catalyst to decontaminate the lethal chemical present. The product should be capable of high sorptive capacity, selectivity and quick response time to neutralize the long lasting harmful effects of nerve agents. Herein, we have utilized organophosphorus hydrolase (OPH) as a non-toxic bio-catalytic material held in with the supporting matrix of poly-β-cyclodextrin (PCD) as a novel sorptive reinforced self-decontaminating material against organophosphate intoxication. OPH coated PCD (OPH-PCD) will not only be providing support for holding enzyme but also would be adsorbing methyl paraoxon (MPO) used as a simulant, in a host-guest inclusion complex formation. Sorption trend for PCD revealed preference towards the more hydrophobic MPO against para-nitrophenol (pNP). The results show sorption capacity of 1.26 mg/g of 100 μM MPO with PCD which was 1.7 times higher compared to pNP. The reaction rate with immobilized OPH-PCD was found to be 23% less compared to free enzyme. With the help of OPH-PCD, continuous hydrolysis (100%) of MPO into pNP was observed for a period of 24 h through packed bed reactor with good reproducibility and stability of enzyme. The long-term stability also confirmed its stable nature for the investigation period of 4 days where it maintained activity. Combined with its fast and reactive nature, the resulting self-decontaminating regenerating material provides a promising strategy for the neutralization of nerve agents and preserving the environment.

V-type nerve agents, known as VX, are organophosphate (OP) compounds, and show extremely toxic effects on human and animals by causing cholinergic overstimulation of synapses. The bacterial organophosphorus hydrolase (OPH) has attracted much attention for detoxifying V-type agents through hydrolysis of the P-S bond. However, low catalytic efficiency of OPH has limited the practical use of the enzyme. Here we present rational design of OPH with high catalytic efficiency for a V-type nerve agent. Based on the model structure of the enzyme and substrate docking simulation, we predicted the key residues that appear to enhance the access of the substrate to the active site of the enzyme, and constructed numerous OPH mutants. Of them, double mutant, L271/Y309A, was shown to exhibit a 150-fold higher catalytic efficiency for VX than the wild-type.

After the removal of SA (Selective Availability), horizontal accuracy of 25m(2dRMS) is easily obtained using GPS (Global Positioning System). In this paper, the error characteristics without SA are analyzed and a navigation algorithm concerns this error characteristics is proposed to further improve the accuracy. The proposed method utilizes the relationship between elevation angle and errors that are remained after ionospheric and troposheric delay compensation. The relationship is derived from real measurements and used as a weighting matrix of weighted least squares estimator. Furthermore, a RAIM (Receiver Autonomous Integrity Monitoring) technique is included to remove abnormal measurements affected by multi-path or low SNR (Signal-to-Noise Ratio). It is shown that using the proposed method, more than 4 times accurate result, which is comparable with DGPS (Differential GPS), can be obtained from experiments with real data. Besides accuracy and reliability, the proposed method reduces large jumps in position and maintains better performance than a method using mask angle to completely remove satellites below this mask angle. Thus it is expected that the proposed method can be efficiently applied to land navigation where some satellites are blocked by building or forest.