Flavonoids have diverse biological functions in human health. All flavonoids contain a common 2-phenyl chromone structure (C6-C3-C6) as a scaffold. Hence, in using such a scaffold, plenty of ...highvalue-added flavonoids can be synthesized by chemical or biological catalyzation approaches. (2S)-Naringenin is one of the most commonly used flavonoid scaffolds. However, biosynthesizing (2S)-naringenin has been restricted not only by low production but also by the expensive precursors and inducers that are used. Herein, we established an induction-free system to de novo biosynthesize (2S)-naringenin in
. The tyrosine synthesis pathway was enhanced by overexpressing feedback inhibition-resistant genes (
and
) and knocking out a repressor gene (
). After optimizing the fermentation medium and conditions, we found that glycerol, glucose, fatty acids, potassium acetate, temperature, and initial pH are important for producing (2S)-naringenin. Using the optimum fermentation medium and conditions, our best strain, Nar-17LM1, could produce 588 mg/l (2S)-naringenin from glucose in a 5-L bioreactor, the highest titer reported to date in
.
In this paper, we develop an adaptive finite element method for the nonlinear steady-state Poisson-Nernst-Planck equations, where the spatial adaptivity for geometrical singularities and boundary ...layer effects are mainly considered. As a key contribution, the steady-state Poisson-Nernst-Planck equations are studied systematically and rigorous analysis for a residual-based a posteriori error estimate of the nonlinear system is presented. With the regularity of the linearized system derived by taking
G
-derivatives of the nonlinear system, we show the robust relationship between the error of solution and the a posteriori error estimator. Numerical experiments are given to validate the efficiency of the a posteriori error estimator and demonstrate the expected rate of convergence. In further tests, adaptive mesh refinements for geometrical singularities and boundary layer effects are successfully observed.
This meta-analysis was aimed to estimate the diagnostic performance of volatile organic compounds (VOCs) as a potential novel tool to screen for the neoplasm of the digestive system. An integrated ...literature search was performed by two independent investigators to identify all relevant studies investigating VOCs in diagnosing neoplasm of the digestive system from inception to 7th December 2020. STATA and Revman software were used for data analysis. The methodological quality of each study was assessed using the Quality Assessment of Diagnostic Accuracy Studies tool. A bivariate mixed model was used and meta-regression and subgroup analysis were performed to identify possible sources of heterogeneity. A total of 36 studies comprised of 1712 cases of neoplasm and 3215 controls were included in our meta-analysis. Bivariate analysis showed a pooled sensitivity of 0.87 (95% confidence interval (CI) 0.83-0.90), specificity of 0.86 (95% CI 0.82-0.89), a positive likelihood ratio of 6.18 (95% CI 4.68-8.17), and a negative likelihood ratio of 0.15 (95% CI 0.12-0.20). The diagnostic odds ratio and the area under the summary ROC curve for diagnosing neoplasm of the digestive system were 40.61 (95% CI 24.77-66.57) and 0.93 (95% CI 0.90-0.95), respectively. Our analyses revealed that VOCs analysis could be considered as a potential novel tool to screen for malignant diseases of the digestive system.
Abstract
Electrochromic supercapacitors (ESCs) are appealing for smart electronic device applications due to their advantages of dual-function integration. Unfortunately, the synchronous ...dual-function evaluation and the essential reaction mechanism are ambiguous. Herein, we constructed a 3D WO
3-x
nanowire networks/fluorine-doped tin oxide (WO
3-x
NWNs/FTO) bifunctional electrode for ESCs by a solvothermal self-crystal seeding method. The synchronous correspondence relationship between the optical and electrochemical performances of the WO
3-x
NWNs/FTO electrode was explored using an operando spectra-electrochemical characterization method. It reveals an excellent areal capacity of 57.57 mF cm
−2
with a high corresponding optical modulation (ΔT) of 85.05% and high optical-electrochemical cycling stability. Furthermore, the synergistic reaction mechanism between the Al
3+
ion intercalation behavior and the surface pseudocapacitance reaction during electrochemical cycling is revealed utilizing in situ X-ray diffraction. Based on these results, an ESC device was constructed by pairing WO
3-x
/FTO as the cathode with V
2
O
5
nanoflowers/FTO (V
2
O
5
NFs/FTO) as the anode, which simultaneously deliver high capacity and large optical modulation. Moreover, the energy storage level of the ESC device could be visually monitored by rapid and reversible color transitions in real time. This work provides a promising pathway to developing multi-functional integrated smart supercapacitors.
•A MXene catalyzed Faraday cage-type ECL immunosensor for GM crops was developed.•MXene catalyzes the ECL reaction of PTCA, enhancing ECL intensity about 4 times.•Sensitivity is doubly improved by ...Faraday cage-type sensor mode and MXene catalysis.•Cry1Ab is detected in the range of 0.005 ∼ 100 ng mL−1 with a LOD 0.001 ng mL−1.•GM maize MON810 is detected in the range of 0.005 % ∼ 2.0 % with a LOD 0.001 %.
Herein, a MXene catalyzed Faraday cage-type electrochemiluminescence (ECL) immunosensor was developed for the detection of transgenic component Cry1Ab protein in genetically modified (GM) crops. The capture unit Fe3O4-Ab1 is Fe3O4 nanoparticles coated by capture antibody Ab1, while the signal unit MXene-PTCA-Ab2 is two-dimensional conductive material MXene with ECL labels 3,4,9,10-perylenetetracarboxylic acid (PTCA) and recognition antibody Ab2 simultaneously immobilized. In presence of the target Cry1Ab, the Faraday cage-type electrochemical immunosensor could be constructed by forming the capture unit-Cry1Ab-signal unit immunocomplex. In addition to the inherently high sensitivity brought by the Faraday cage-type sensor construction mode, MXene in the signal unit catalyzes the reduction of dissolved O2 to form reactive oxygen species which could accelerate the ECL reaction, resulting in a secondary ECL enhancement of PTCA and ensuing higher detection sensitivity. Under the optimized experimental conditions, Cry1Ab protein and GM maize MON810 could be quantitatively detected in the range of 0.005 ∼ 100 ng mL−1 and 0.005 % ∼ 2.0 %, with limit of detections (LODs) 0.001 ng mL−1 and 0.001 % respectively. Selectivity, stability, repeatability, precision, and accuracy are all satisfactory. Detection of actual samples is successful, showing its application prospect in the field of agriculture and food safety.
This article successfully prepared porous NiMoO
4
sheet-like structured nanomaterials deposited on carbon cloth using the freeze-drying method. The morphology and phase structure were characterized ...by SEM, TEM, and XRD, proving that the material is NiMoO
4
porous nanosheets. The NiMoO
4
porous nanosheets have a large specific surface area, which increases the reaction sites of the material, shortens the transmission distance of electrons and ions, accelerates the reaction rate, and thus improves the charge storage capacity. We conducted electrochemical performance tests on the material, and the test results showed that the specific capacity was 1683 F/g at a current density of 5 A/g. After 5000 cycles, the capacitance retention rate was 99.7%. We further assembled NiMoO
4
porous nanosheets as positive electrodes and CNTs as negative electrodes to form solid-state asymmetric capacitor devices. At a current density of 15 A/g and a working window voltage of 1.6 V, the asymmetric device has an energy density of 70.8 Wh/Kg and a power density of 7000 W/Kg. After 10,000 cycles at a current density of 5 A/g, the device exhibits excellent cycling stability with a capacitance retention rate of 87.6%. This article provides a valuable reference for the development of electrode materials for capacitors.
An electrochemiluminescence (ECL) inhibition method combined with molecularly imprinted solid phase extraction (MISPE) was developed for quantitative determination of malachite green (MG) residues in ...fish. It was found that MG could strongly inhibit the ECL signal of luminol. Under the optimized conditions, the quenched ECL intensity versus the logarithm of the concentration of MG was in good linear relationship over a concentration range from 20 to 5000 ppt. The method detection limit was found to be about 6 ppt. Molecularly imprinted polymers (MIPs) were synthesized as solid phase extraction (SPE) sorbents, and MISPE was used for the selective extraction and purification of MG. By carrying out the oxidation reaction with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), which could convert leucomalachite green (LMG) into MG, this method was successfully applied to determine MG residues in fish. A possible mechanism for the quenching effects of MG on luminol was also proposed.
In this paper, a series of experiments were performed to investigate the effects of superhydrophilic and hydrophilic surfaces on the heat transfer performance and slug motion for oscillating heat ...pipes (OHPs). Deionized water was used as the working fluid. The surfaces of the OHPs were copper, superhydrophilic, hydrophilic and hydrophobic surfaces with contact angles of 73.4°, 0°, 12.9° and 141.5°, respectively. The heat transfer performance in six-turn OHPs was higher than in four-turn OHPs. Experimental results showed that the surface wettability remarkably influenced the slug motion and thermal performance of OHPs. The liquid slug movements became stronger both in superhydrophilic and hydrophilic OHPs as opposed to the copper OHP, while the global heat transfer performance of the superhydrophilic and hydrophilic OHPs increased in the six-turn OHP. For six-turn OHPs, the maximum displacement of the liquid slug in the hydrophilic OHPs and superhydrophilic OHPs increased by 5–60% and 25–60%, respectively, in comparison with that of copper OHPs. The heat transfer performance of superhydrophilic OHPs and hydrophilic OHPs increased by 5–15% and 15–25%, respectively, in comparison with that of copper OHPs. The hydrophilic surface improved the heat transport capability of OHPs, and the maximum displacement and velocity of the liquid slug increased. The startup temperature of the four-turn and six-turn OHPs varied from 45 to 55°C and 35 to 45°C, respectively. The startup temperature of the four-turn and six-turn superhydrophilic OHPs varied from 40 to 55°C and from 35 to 50°C, respectively. The startup temperature of the four-turn and six-turn hydrophilic OHPs varied from 40 to 50°C and from 30 to 40°C, respectively. The hydrophilic OHP also showed a better startup performance than the copper OHP. At heat input of 150W, the thermal resistance for the four-turn hydrophobic OHPs was about two times greater than that of copper OHPs. The global heat transfer performance of the superhydrophilic OHP for the four-turn OHP was lower than that of the four-turn OHPs with hydrophilic and pure copper OHPs.
Streptococcus mutans is a major pathogen causing human dental caries. As a Gram-positive bacterium with a small genome (about 2 Mb) it is considered a poor source of natural products. Due to a recent ...explosion in genomic data available for S. mutans strains, we were motivated to explore the natural product production potential of this organism. Bioinformatic characterization of 169 publically available genomes of S. mutans from human dental caries revealed a surprisingly rich source of natural product biosynthetic gene clusters. Anti-SMASH analysis identified one nonribosomal peptide synthetase (NRPS) gene cluster, seven polyketide synthase (PKS) gene clusters and 136 hybrid PKS/NRPS gene clusters. In addition, 211 ribosomally synthesized and post-translationally modified peptides (RiPPs) clusters and 615 bacteriocin precursors were identified by a combined analysis using BAGEL and anti-SMASH. S. mutans harbors a rich and diverse natural product genetic capacity, which underscores the importance of probing the human microbiome and revisiting species that have traditionally been overlooked as "poor" sources of natural products.
A Faraday cage-type aptasensor has been developed for dual-mode detection of a common bacterial pathogen
Vibrio parahaemolyticus
(VP) by electrochemiluminescence (ECL) and differential pulse ...voltammetry (DPV), using a multi-functionalized material Pb
2+
-Ru-MOF@Apt2 as signal unit. The recognition aptamer Apt2 recognizes VP; specifically, ruthenium-based metal organic framework (Ru-MOF) and lead ions (Pb
2+
) embedded produce an ECL signal at a working potential from 0 to 1.5 V and DPV signal from − 0.3 to − 0.8 V vs. Ag/AgCl. Since Ru-MOF is a two-dimensional conductive material signal unit overlapped onto the electrode surface to form a Faraday cage-type aptasensor. Thus, electrons could be easily exchanged between electrode and signal tags without being hindered by micron-size VP, resulting in a high detection sensitivity with a detection limit of 1.7 CFU mL
−1
. In addition, dual-mode detection was achieved, improving the accuracy and reliability of rapid field detection. Stability and selectivity were also satisfactory. The tests of real samples indicate that this Faraday cage-type aptasensor is suited for rapid detection of VP and analog pathogens and shows great potential in food safety.
Graphical abstract
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