An Automated, Pre-Programmed, Multiplexed, Hydraulic Microvalve

An automated, pre-programmed, multiplexed hydraulic valve actuator is described. The valve is membrane-based and normally open. In contrast to the membrane-based pneumatic valve, the hydraulic valve uses hydraulic liquid to exert the control pressure. The line pressure is controlled with a roller moving over a prefabricated topology. Multiple rollers, each traversing its own track, are assembled into a single carriage, which can be actuated either manually or with a single computer-controlled motor. A valve manifold and roller actuators are designed, fabricated, and tested to demonstrate three-way valve actuation in a pre-determined sequence. The performance of the valve is evaluated and the utility of the valve in the operation of a micro thermal cycler was demonstrated. Hydraulic controllers of the type described here can be operated either manually or under computer control and provide an inexpensive means of controlling flow in lab-on-a-chip devices

Novel activation of peroxymonosulfate by biochar derived from rice husk toward oxidation of organic contaminants in wastewater

In this study, novel activation of peroxymonosulfate (PMS) by biochar derived from rice husk (generally considered useless agricultural wastes in Vietnam) toward organic pollutants from wastewater was investigated. The basic properties of biochar were characterized through field-emission scanning electron microscopy (FE-SEM), elemental analysis (EA) and gas adsorption analysis (BET). Operating parameters including PMS concentration, dose of biochar and initial concentration of target pollutants (tetracycline and bisphenol A) were systematically studied. The results showed that biochar derived from rice husk effectively activated of PMS, leading to high degradation of organic pollutants in wastewater. The degradation efficiency of organic pollutants increased with increasing PMS concentration and amount of biochar. The reuse of rice husk biochar and the possible mechanism for PMS activation were proposed accordingly. In addition, the evaluation of potential available rice husk biomass in Vietnam was discussed. These findings suggest a novel rice husk biochar for activation of PMS toward toxic organic pollutants from wastewater

An integrated, self-contained microfluidic cassette for isolation, amplification, and detection of nucleic acids

A self-contained, integrated, disposable, sample-to-answer, polycarbonate microfluidic cassette for nucleic acid-based detection of pathogens at the point of care was designed, constructed, and tested. The cassette comprises on-chip sample lysis, nucleic acid isolation, enzymatic amplification (polymerase chain reaction and, when needed, reverse transcription), amplicon labeling, and detection. On-chip pouches and valves facilitate fluid flow control. All the liquids and dry reagents needed for the various reactions are pre-stored in the cassette. The liquid reagents are stored in flexible pouches formed on the chip surface. Dry (RT-)PCR reagents are pre-stored in the thermal cycling, reaction chamber. The process operations include sample introduction; lysis of cells and viruses; solid-phase extraction, concentration, and purification of nucleic acids from the lysate; elution of the nucleic acids into a thermal cycling chamber and mixing with pre-stored (RT-)PCR dry reagents; thermal cycling; and detection. The PCR amplicons are labeled with digoxigenin and biotin and transmitted onto a lateral flow strip, where the target analytes bind to a test line consisting of immobilized avidin-D. The immobilized nucleic acids are labeled with up-converting phosphor (UCP) reporter particles. The operation of the cassette is automatically controlled by an analyzer that provides pouch and valve actuation with electrical motors and heating for the thermal cycling. The functionality of the device is demonstrated by detecting the presence of bacterial B.Cereus, viral armored RNA HIV, and HIV I virus in saliva samples. The cassette and actuator described here can be used to detect other diseases as well as the presence of bacterial and viral pathogens in the water supply and other fluids

MAP kinase in signal transduction pathways of the plant oxidative burst

The oxidative burst constitutes one of the most rapid defense responses characterized in the plant kingdom. I have observed that four distinct elicitors of the soybean oxidative burst activate kinases of masses ∼44 kDa and ∼47 kDa. Immunological and biochemical studies reveal that the activated 44 kDa and 47 kDa kinases are MAP kinase family members. To positively identify them, I cloned five different soybean MAP kinases (GMK1 through GMK5) using RT-PCR method. All five MAP kinases contain the conserved TEY phosphorylation sites that are characteristic of MAP kinases. Using a C-terminus specific antibody, the 47 kDa kinase was identified as the GMK1. These data suggest that GMK1 is involved in the signal transduction pathways leading to the oxidative bust. In eukaryotic cells, MAPK isoforms are generally activated by a specific MAPK kinase (MAPKK). To study the MAPK activating pathway leading to the oxidative burst, I cloned three different soybean MAP kinase kinases (GMKK1 through GMKK3). Then, all the GMK1-5 and GMKK1-3 proteins were expressed and purified from E. coli. Interestingly, the recombinant GMKK1 protein could activate both GMK1 and GMK2 in vitro. This result suggests that the activation of GMK1, the soybean MAP kinase involved in the oxidative burst, is mediated by the MAP kinase kinase GMKK1. Based on these and other observations, a preliminary sequence of signaling steps linking elicitor stimulation, kinase activation, and Ca2+ entry, to initiation of oxidant production is proposed

Improved Direct Deadbeat Voltage Control with an Actively Damped Inductor-Capacitor Plant Model in an Islanded AC Microgrid

A direct deadbeat voltage control design method for inverter-based microgrid applications is proposed in this paper. When the inductor-capacitor (LC) filter output voltage is directly controlled using voltage source inverters (VSIs), the plant dynamics exhibit second-order resonant characteristics with a load current disturbance. To effectively damp the resonance caused by the output LC filter, an active damping strategy that does not cause additional energy loss is utilized. The proposed direct deadbeat voltage control law is devised from a detailed, actively damped LC plant model. The proposed deadbeat control method enhances voltage control performance owing to its better disturbance rejection capability than the conventional deadbeat or proportional-integral-based control methods. The most important advantage of the proposed deadbeat control method is that it makes the deadbeat control more robust by bringing discrete closed-loop poles closer to the origin. Simulation and experimental results are shown to verify the enhanced voltage control performance and stability of the proposed voltage control method

Control of chloroplast development by active DNA demethylation

DNA methylation is an epigenetic modification regulating genome stability and diverse biological processes. In plants, RNA-dependent DNA methylation (RdDM) establishes de novo DNA methylation, whereas DNA demethylases remove established DNA methylation. ROS1, DML2, DML3 (RDD) are DNA demethylases known to function in somatic cells. Despite of their significant effect on the DNA methylation pattern, only a few biological processes, such as development of stomata or trachea element and immune responses, have been associated with DNA demethylation. Here, we report that chloroplast development can be controlled by DNA demethylation pathway. From the suppressor mutant screening of mild chloroplast protease mutant clpt, we identified suppressor of clpt1 (soct1) as a mutant allele of INCREASED DNA METHYLATION3 (IDM3) a subunit of IDM complex which regulates targeting of ROS1. Mutants of ROS1 and IDM complex also suppressed clpt, which was mediated by DNA hypermethylation in the mutants. We also dentified soct2/3/4 as mutant alleles of NRPD1 or RDR2 which are components of 24-nt sRNA biogenesis pathway. The suppression of clpt by soct2/3/4 probably is associated with reduced ROS1 expression, which is caused by loss-of DNA methylation at the promoter of ROS1 (MEMS). In addition, unexpectedly, clpt DNA was hypermethylated at RdDM target sites. The clpt DNA hypermethylation was largely rescued in clpt mbd7, suggesting that chloroplast developmental defect induced RdDM-mediated DNA methylation in clpt. These results show that chloroplast development can be regulated by DNA demethylation pathway. Also, it suggests RdDM-mediated DNA methylation as a stress response against chloroplast developmental defect. Thus, this study offers a novel relationship between chloroplast development and DNA methylation.2

Control of Chloroplast Development by Active DNA demethylation

In plants, RNA-dependent DNA methylation (RdDM) establishes de novo DNA methylation, whereas DNA demethylases remove established DNA methylation. Despite of significant effect of these pathways on the DNA methylation, only a few biological processes have been associated with DNA methylation. Here we performed a forward genetic screen in Arabidopsis for suppressors of chloroplast Clp protease mutant clpt. We identified SUPPRESSOR OF CLPT1 (SOCT1) encoding IDM3, SOCT2 encoding NRPD1, SOCT3/4 encoding RDR2. T-DNA mutants of ROS1 and IDM3 interacting partners suppressed clpt, which was mediated by DNA hypermethylation. Also, suppression of clpt by soct2/3/4 was associated reduced ROS1 activity in the mutants. In addition, we also found that chloroplast developmental defect of clpt induces DNA methylation at RdDM target sites. Together, we revealed that chloroplast development can be regulated by DNA demethylation. Also, we suggest that DNA methylation as a stress response for adjusting chloroplast developmental stresses.2