A high-quality filler within mixed matrix membranes, coupled with uniform dispersity, endows a high-efficiency transfer pathway for the significant improvement on separation performance. In this work, a zeolite-typed MCM-22 filler is reported that is doped into polydimethylsiloxane (PDMS) matrix by ultrafast photo-curing technique. The unique structure of nanosheets assembly layer by layer endows the continuous transfer channels towards penetrate molecules because of the inter-connective nanosheets within PDMS matrix.
View Article and Find Full Text PDFIn the laboratory study of alkali-silica reaction (ASR), models attempt to predict the service life of concrete due to ASR by correlating the performance of concrete at high and low temperatures. However, the consequences of elevating temperature are not so encouraging. In this paper, the influence of temperature on the expansion of 2-graded concrete and 3-graded concrete caused by ASR was investigated by curing the concrete under different temperatures ranging from 40 °C to 80 °C.
View Article and Find Full Text PDFDespite extensive research, the relationship between the progression of the alkali-silica reaction (ASR) and the expansion of concrete due to ASR, particularly for the heterogeneous aggregate with slow reactivity, is not thoroughly understood. In this paper, the dissolution kinetics of reactive silica present in sandstone when exposed to NaOH solutions, alongside the expansion characteristics of rock prisms under ASR conditions, were studied. The experimental results indicate that ASR behaves as a first-order reaction, accompanied by an exponential decrease in the concentration of OH over time, and the dissolution rate of silica is predominantly governed by diffusion dynamics.
View Article and Find Full Text PDFACS Appl Mater Interfaces
July 2023
X-ray detectors based on conventional semiconductors with large atomic numbers are suffering from the poor stability under a high dose rate of ionizing irradiation. In this work, we demonstrate that a wide band gap ceramic-boron nitride with small atomic numbers could be used for sensitive X-ray detection. Boron nitride samples showed excellent resistance to ionizing radiation, which have been systematically studied with the neutron- and electron-aging experiments.
View Article and Find Full Text PDFTo solve the issue of the poor temperature stability of conventional modified asphalt, polyurethane (PU) was used as a modifier with its corresponding curing agent (CA) to prepare thermosetting PU asphalt. First, the modifying effects of the different types of PU modifiers were evaluated, and the optimal PU modifier was then selected. Second, a three-factor and three-level L9 (3) orthogonal experiment table was designed based on the preparation technology, PU dosage, and CA dosage to prepare the thermosetting PU asphalt and asphalt mixture.
View Article and Find Full Text PDFFlux balance analysis (FBA) is an important method for calculating optimal pathways to produce industrially important chemicals in genome-scale metabolic models (GEMs). However, for biologists, the requirement of coding skills poses a significant obstacle to using FBA for pathway analysis and engineering target identification. Additionally, a time-consuming manual drawing process is often needed to illustrate the mass flow in an FBA-calculated pathway, making it challenging to detect errors or discover interesting metabolic features.
View Article and Find Full Text PDFFront Bioeng Biotechnol
December 2022
A promoter plays a crucial role in controlling the expression of the target gene in cells, thus being one of the key biological parts for synthetic biology practices. Although significant efforts have been made to identify and characterize promoters with different strengths in various microorganisms, the compatibility of promoters within different hosts still lacks investigation. In this study, we chose the native P promoter of to investigate nucleotide sequences within promoter regions affecting promoter compatibility between and .
View Article and Find Full Text PDFZymomonas mobilis metabolizes sugar anaerobically through the Entner-Doudoroff pathway with less ATP generated for lower biomass accumulation to direct more sugar for product formation with improved yield, making it a suitable host to be engineered as microbial cell factories for producing bulk commodities with major costs from feedstock consumption. Self-flocculation of the bacterial cells presents many advantages, such as enhanced tolerance to environmental stresses, a prerequisite for achieving high product titers by using concentrated substrates. ZM401, a self-flocculating mutant developed from ZM4, the unicellular model strain of Z.
View Article and Find Full Text PDFInhibitors in lignocellulosic hydrolysates are toxic to Zymomonas mobilis and reduce its bioethanol production. This study revealed cysteine supplementation enhanced furfural tolerance in Z. mobilis with a 2-fold biomass increase.
View Article and Find Full Text PDFBiotechnol Biofuels
December 2021
Background: Efficient use of glucose and xylose is a key for the economic production of lignocellulosic biofuels and biochemicals, and different recombinant strains have been constructed for xylose utilization including those using Zymomonas mobilis as the host. However, the xylose utilization efficiency still needs to be improved. In this work, the strategy of combining metabolic engineering and adaptive laboratory evolution (ALE) was employed to develop recombinant Z.
View Article and Find Full Text PDFBackground: To explore possible associations between polybrominated diphenyl ether (PBDE) exposure and patients with abnormal thyroid hormone levels whose thyroid function parameters are above normal ranges.
Methods: The serum of 40 patients with thyroid hormone abnormalities was collected in Kunming. triiodothyronine (T3), thyroxine (T4), free triiodothyronine (FT3), free thyroxine (FT4), and thyroid-stimulating hormone (TSH) were detected in serum using chemiluminescence.
The model ethanologenic bacterium Zymomonas mobilis has many advantages for diverse biochemical production. Although the impact of temperature especially high temperature on the growth and ethanol production of Z. mobilis has been reported, the transcriptional profiles of Z.
View Article and Find Full Text PDFThe development and implement of microbial chassis cells can provide excellent cell factories for diverse industrial applications, which help achieve the goal of environmental protection and sustainable bioeconomy. The synthetic biology strategy of Design-Build-Test-Learn (DBTL) plays a crucial role on rational and/or semi-rational construction or modification of chassis cells to achieve the goals of "Building to Understand" and "Building for Applications". In this review, we briefly comment on the technical development of the DBTL cycle and the research progress of a few model microorganisms.
View Article and Find Full Text PDFBackground: Acid pretreatment is a common strategy used to break down the hemicellulose component of the lignocellulosic biomass to release pentoses, and a subsequent enzymatic hydrolysis step is usually applied to release hexoses from the cellulose. The hydrolysate after pretreatment and enzymatic hydrolysis containing both hexoses and pentoses can then be used as substrates for biochemical production. However, the acid-pretreated liquor can also be directly used as the substrate for microbial fermentation, which has an acidic pH and contains inhibitory compounds generated during pretreatment.
View Article and Find Full Text PDFAlthough rational design-based metabolic engineering has been applied widely to obtain promising microbial biocatalysts, conventional strategies such as adaptive laboratory evolution (ALE) and mutagenesis are still efficient approaches to improve microorganisms for exceptional features such as a broad spectrum of substrate utilization, robustness of cell growth, as well as high titer, yield, and productivity of the target products. In this chapter, we describe the procedure to generate mutant strains with desired phenotypes using ALE and a new mutagenesis approach of Atmosphere and Room Temperature Plasma (ARTP). In addition, we discuss the methodology to combine next-generation sequencing (NGS)-based genome-resequencing and RNA-Seq transcriptomics approaches to characterize the mutant strains and connect the phenotypes with their corresponding genotypic changes.
View Article and Find Full Text PDFThe methane (CH)/oxygen (O) gas supply ratios significantly affect the cell growth and metabolic pathways of aerobic obligate methanotrophs. However, few studies have explored the CH/O ratios of the inlet gas, especially for the CH concentrations within the explosion range (5∼15% of CH in air). This study thoroughly investigated the molecular mechanisms associated with the impact of different CH/O ratios on cell growth of a model type I methanotroph 5GB1 cultured at five different CH/O supply molar ratios from 0.
View Article and Find Full Text PDFFront Bioeng Biotechnol
March 2020
sRNAs represent a powerful class of regulators that influences multiple mRNA targets in response to environmental changes. However, very few direct sRNA-sRNA interactions have been deeply studied in any organism. is a bacterium with unique ethanol-producing metabolic pathways in which multiple small RNAs (sRNAs) have recently been identified, some of which show differential expression in ethanol stress.
View Article and Find Full Text PDFZymomonas mobilis is a model bacterial ethanologen and has been engineered to produce lignocellulosic biofuels and biochemicals such as 2,3-butanediol. We have previously identified promoters of different strengths using systems biology datasets and characterized them using the flow cytometry-based dual reporter-gene system. Here, we further demonstrated the capability of applying the dual reporter-gene system and omics datasets on discovering inducible promoters.
View Article and Find Full Text PDFBackground: Biological routes for utilizing both carbohydrates and lignin are important to reach the ultimate goal of bioconversion of full carbon in biomass into biofuels and biochemicals. Recent biotechnology advances have shown promises toward facilitating biological transformation of lignin into lipids. Natural and engineered strains (e.
View Article and Find Full Text PDFBackground: is a model bacterial ethanologen with many systems biology studies reported. Besides lignocellulosic ethanol production, has been developed as a platform for biochemical production through metabolic engineering. However, identification and rigorous understanding of the genetic origins of cellular function, especially those based in non-coding region of DNA, such as promoters and ribosomal binding sites (RBSs), are still in its infancy.
View Article and Find Full Text PDFTrends Biotechnol
September 2019
Great effort has been devoted to engineering Saccharomyces cerevisiae with pentose metabolism through the oxido-reductase pathway for cellulosic ethanol production, but intrinsic cofactor imbalance is observed, which substantially compromises ethanol yield. Zymomonas mobilis not only can be engineered for pentose metabolism through the isomerase pathway without cofactor imbalance but also metabolizes sugar through the Entner-Doudoroff pathway with less ATP and biomass produced for more sugar to be used for ethanol production. Moreover, the availabilities of genome sequence information for multiple Z.
View Article and Find Full Text PDFDehydrins are a family of plant proteins that accumulate in response to dehydration stresses, such as low temperature, drought, high salinity, or during seed maturation. We have previously constructed cDNA libraries from leaves of naturally non-acclimated (NA; leaf LT, temperature that results in 50% injury of maximum, approximately -7°C) and cold-acclimated (CA; leaf LT approximately -50°C) plants and analyzed expressed sequence tags (ESTs). Five ESTs were identified as dehydrin genes.
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