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Microbial engineering of Methylorubrum extorquens AM1 to enhance CO2 conversion into formate
No full textMethylorubrum extorquens AM1 has the potential to consume C1 feedstock to produce a wide range of biomaterials, from bioplastic to pharmaceutical. However, the synthetic biology tools for engineering M. extorquens AM1 need to be employed for precise control of recombinant enzyme expression. In this study, we presented an approach to improve the expression level of formate dehydrogenase 1 from M. extorquens AM1 (MeFDH1) using an efficient terminator and 5???-untranslated region (5???-UTR) design for enhanced carbon dioxide (CO2) conversion activity of whole-cell biocatalyst. The rrnB terminator significantly increased mRNA levels of MeFDH1 alpha and beta subunits by 8.2-fold and 11-fold, respectively, compared to the T7 terminator. Moreover, enzyme production was 1.6-fold higher with 2.1 mg/wet cell weight (WCW) using rrnB terminator. Homologous 5???-untranslated regions (5???-UTR) determined based on proteomics data and UTR designer also influenced the expression level of MeFDH1. The 5???-UTR of the formaldehyde activating enzyme (fae) was the strongest, with 2.5-fold higher expression than that of the control sequence (T7g-10L). Furthermore, the electrochemical reaction of recombinant strains as whole-cell biocatalysts was investigated for their applicability to CO2 conversion, showing enhanced formate productivity. The recombinant strain containing the 5???-UTR sequence of fae exhibited formate productivity of 5.0 mM/h, 2.3-fold higher than that of the control strain (T7). Overall, this study suggested practical applications for CO2 conversion into bioavailable formate and provided valuable insights for recombinant expression systems in methylotrophic strains
Enhanced Stretchability of Wavy-Structured Thermally Grown Silicon Dioxide Films for Stretchable Encapsulation
No full textAligned wavy-structured thermally grown silicon dioxide films are fabricated for stretchable encapsulation films. Uniaxial stretchability is investigated with micromechanics modeling, which can elucidate the stretchability arising from the wavy structure and the properties of the materials. The wavy-structured films with optimum combinations of film thickness and wavy structure show 20.1% of uniaxial stretchability and 1.11 x 10(-6) g m(-2) day(-1) of water vapor transmission rate (WVTR), simultaneously. It shows highly reliable barrier properties even after 1000 stretching cycles at 90% of their stretchability
Heat-Up Process: Road to Synthesizing Monodisperse Nanoparticles
No full textLarge-scale synthesis of monodisperse nanoparticles is highly desirable for practical applications of nanoparticles in various fields of emerging technology. Among colloidal synthetic routes of monodisperse nanoparticles, heat-up process, which involves a gradual heating of precursor solution in a batch reactor, has received utmost interest after its successful size-controlled synthesis of various kinds of nanoparticles. In this essay, we discuss the fundamental research regarding the synthesis of monodisperse nanoparticles and describe how researchers developed the heat-up process. The mechanistic insights into this synthetic method and the discovery of size-dependent properties of monodisperse nanoparticles are also presented. We further emphasize its great impacts on utilizing monodisperse nanoparticles synthesized via the heat-up process for biomedical technology, energy conversion and storage devices, as well as electronic and optoelectronic devices
Moving Target Landing of a Quadrotor Using Robust Optimal Guaranteed Cost Control
No full textDear Editor, This letter proposes a robust control strategy for the autonomous landing of a quadrotor on a moving target. Specifically, a force command that consists of a cascade dynamics estimator and an optimal guaranteed cost control law is exploited for the position-loop tracking. Then, an orientation constraint torque command is employed for the attitude-loop tracking such that the quadrotor refrains from flipping during the landing operation. Stability analysis indicates that the overall closed-loop system is asymptotically stable. Finally, flight experiments validate and access the theoretical results
A Psychophysical Experimental Method to Measure the Hue of Low Chroma Color
No full textThe psychophysical experimental methods were investigated to find an effective method for measuring color perception for low chroma color. Hue of the display stimuli was measured by two psychophysical experiments. One is the forced-choice experiment. The participants classified the hue of the stimulus as either yellow or blue and red or green. The proportion from the repeated responses was plotted on the chromaticity diagram with two hue axis. The angle from the positive x-axis to the point induced from the hue proportion represents the hue angle. The hue angle was converted to the 400-hue quadrature scale to express the hue as the percentage of two neighboring unique hues. The other experimental method is the magnitude estimation. The participants judged the hue of the stimulus as a number. As the result, the participants evaluated the color of the stimulus easily with the forced-choice method. In addition, the standard deviation between participants was small in the forced-choice experiment. It means that the forced-choice method is reliable. Therefore, this study expects to use the forced choice method to measure hue of low chroma color
A review on control and abatement of soil pollution by heavy metals: Emphasis on artificial intelligence in recovery of contaminated soil
No full text"Save Soil Save Earth" is not just a catchphrase; it is a necessity to protect soil ecosystem from the unwanted and unregulated level of xenobiotic contamination. Numerous challenges such as type, lifespan, nature of pollutants and high cost of treatment has been associated with the treatment or remediation of contaminated soil, whether it be either on-site or off-site. Due to the food chain, the health of non-target soil species as well as human health were impacted by soil contaminants, both organic and inorganic. In this review, the use of microbial omics approaches and artificial intelligence or machine learning has been comprehensively explored with recent ad-vancements in order to identify the sources, characterize, quantify, and mitigate soil pollutants from the envi-ronment for increased sustainability. This will generate novel insights into methods for soil remediation that will reduce the time and expense of soil treatment
Combination four different ensemble algorithms with the generalized linear model (GLM) for predicting forest fire susceptibility
No full textIn this study, the generalized linear model (GLM) and four ensemble methods (partial least squares (PLS), boosting, bagging, and Bayesian) were applied to predict forest fire hazard in the Chalus Rood watershed in the Mazandaran Province, Iran. Data from 108 historical forest fire events collected through field surveys were applied as the basis of the analysis. About 70% of the data were used for training the models, while the remaining 30% was used for testing. A total of 14 environmental, climatic, and vegetation variables were used as input features to the models to predict forest fire probability. After conducting a multicollinearity test on the independent variables, the GLM and the ensemble models were applied for modeling. The efficiency of the models was evaluated using receiver operating characteristic (ROC) curve parameters. Results from the validation process, based on the area under the ROC curve (AUC), showed that the GLM, PLS-GLM, boosted-GLM, Bagging-GLM, and Bayesian-GLM models had efficiencies of 0.79, 0.75, 0.81, 0.84, and 0.85, respectively. The results indicated that all ensemble methods, except the PLS algorithm, improved the performance of the GLM model in modeling forest fire hazards in the Chalus Rood watershed, with the Bayesian algorithm being the most efficient method among them
Feasibility analysis of AERONET lunar AOD for nighttime particulate matter estimation
No full textSeveral studies have attempted to estimate particulate matter (PM) concentrations using aerosol optical depth (AOD), based on AOD and PM relationships. Owing to the limited availability of nighttime AOD data, PM estimation studies using AOD have focused on daytime. Recently, the Aerosol Robotic Network (AERONET) produced nighttime AOD, called lunar AOD, providing an opportunity to estimate nighttime PM. Nighttime AOD measurements are particularly important as they help fill gaps in our understanding of aerosol variability and its impact on the atmosphere, as there are significant variations in AOD between day and night. In this study, the relationship between lunar AOD and PM was investigated using data from AERONET station, meteorological station, and air pollution station in Seoul Metropolitan area from May 2016 to December 2019, and then PM estimation model was developed covering both daytime and nighttime using random forest machine learning techniques. We have found the differences in the importance of variables affecting the AOD-PM relationship between day and night from the random forest model. The AOD-PM relationship in the daytime was more affected by time-related variables, such as the day of the year among the variables. The new model was developed using additional lunar AOD data to estimate continuous PM concentrations. The results have shown that the model based on lunar AOD data estimated well PM10 and PM2.5 with similar performance of model using solar AOD. The results imply the possibility of seamless near-surface PM concentration data on a large scale once satellites produce nighttime AOD data
Statistical analysis of S-N type environmental fatigue data of Ni-base alloy welds using weibull distribution
No full textIn this study, the probabilistic fatigue life model for Ni-base alloys was developed based on the Weibull distribution using statistical analysis of fatigue data reported in NUREG/CR-6909 and the new fatigue data of Alloy 52M/152 and 82/182. The developed Weibull model can consider right-censored data (i.e., non-failed data) and quantify the improved safety (or reliability) based on the level of failure probability.
The overall margin in the current fatigue design limit model (ASME design curve ?? NUREG/CR-6909 Fen model) is similar to that of the Weibull model with a cumulative failure probability of approximately 2.5%. The margin in the current fatigue design limit model demonstrated inconsistencies for the Ni-base alloy weld data, whereas the Weibull model showed a consistent margin. Therefore, the Weibull model can systematically mitigate the excessive safety margin
Effect of a Tube Diameter on Single Bubble Condensation in Subcooled Flow
No full textBubble condensation, which involves the interaction of bubbles within the subcooled liquid flow, plays an important role in the effective control of thermal devices. In this study, numerical simulations are performed using a VOF (Volume of Fluid) model to investigate the effect of tube diameter on bubble condensation. As the tube diameter decreases, condensation bubbles persist for a long time and disappear at a higher position. It is observed that for small tube diameters, the heat transfer coefficients of condensation bubbles, which is a quantitative parameter of condensation rate, are smaller than those for large tube diameters. When the tube diameter is small, the subcooled liquid around the condensing bubble is locally participated in the condensation of the bubble to fill the reduced volume of the bubble due to the generation of a backflow in the narrow space between the bubble and the wall, so that the heat transfer coefficient decreases