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Lactate is an important monomer for the synthesis of poly-lactate (PLA), which is a substitute for the petrochemical plastics. To achieve the goal of high lactate titer, rate, and yield for commercial production, efficient lactate production pathway is needed as well as genetic targets that affect high lactate production and tolerance. In this study, an LldR-based d-lactate biosensor with a broad dynamic range was first applied into Zymomonas mobilis to select mutant strains with strong GFP fluorescence, which could be the mutant strains with increased d-lactate production. Then, LldR-based d-lactate biosensor was combined with a genome-wide CRISPR interference (CRISPRi) library targeting the entire genome to generate thousands of mutants with gRNA targeting different genetic targets across the whole genome. Specifically, two mutant libraries were selected containing 105 and 104 mutants with different interference sites from two rounds of fluorescence-activated cell sorting (FACS), respectively. Two genetic targets of ZMO1323 and ZMO1530 were characterized and confirmed to be associated with the increased d-lactate production, further knockout of ZMO1323 and ZMO1530 resulted in a 15% and 21% increase of d-lactate production, respectively. This work thus not only established a high-throughput approach that combines genome-scale CRISPRi and biosensor-assisted screening to identify genetic targets associated with d-lactate production in Z. mobilis, but also provided a feasible high-throughput screening approach for rapid identification of genetic targets associated with strain performance for other industrial microorganisms.

Abstract Background Extensive muscle atrophy is a common occurrence in orthopaedics patients who are bedridden or immobilized. The incidence is higher in intensive care unit (ICU) inpatients. There is still controversy about how to use neuromuscular electrical stimulation (NMES) in ICU patients. We aim to compare the effectiveness and safety of NMES to prevent muscle atrophy in intensive care unit (ICU) patients without nerve injury. Methods ICU patients without central and peripheral nerve injury were randomized into experimental group I (Exp I: active and passive activity training (APAT) + NMES treatment on the gastrocnemius and tibialis anterior muscle), experimental group II (Exp II: APAT + NMES treatment on gastrocnemius alone), and control group (Ctl: APAT alone). Changes in the strength of gastrocnemius, the ankle range of motion, and the muscle cross-section area of the lower leg were evaluated before and after the intervention. Also, changes in prothrombin time, lactic acid, and C-reactive protein were monitored during the treatment. Results The gastrocnemius muscle strength, ankle joint range of motion, and cross-sectional muscle area of the lower leg in the three groups showed a downward trend, indicating that the overall trend of muscle atrophy in ICU patients was irreversible. The decrease in gastrocnemius muscle strength in Exp I and Exp II was smaller than that in the control group (P 0.05). Conclusion In addition to early exercise training, NMES should be applied to prevent muscle atrophy for patients without nerve injury in ICU. Also, simultaneous NMES treatment on agonist/antagonist muscle can enhance the effect of preventing muscle atrophy. Trial registration This study was prospectively registered in China Clinical Trial Registry ( www.chictr.org.cn ) on 16/05/2020 as ChiCTR2000032950.

Lactate is the precursor for polylactide. In this study, a lactate producer of Z. mobilis was constructed by replacing ZMO0038 with LmldhA gene driven by a strong promoter PadhB, replacing ZMO1650 with native pdc gene driven by Ptet, and replacing native pdc with another copy of LmldhA driven by PadhB to divert carbon from ethanol to D-lactate. The resultant strain ZML-pdc-ldh produced 13.8 ± 0.2 g/L lactate and 16.9 ± 0.3 g/L ethanol using 48 g/L glucose. Lactate production of ZML-pdc-ldh was further investigated after fermentation optimization in pH-controlled fermenters. ZML-pdc-ldh produced 24.2 ± 0.6 g/L lactate and 12.9 ± 0.8 g/L ethanol as well as 36.2 ± 1.0 g/L lactate and 40.3 ± 0.3 g/L ethanol, resulting in total carbon conversion rate of 98.3% ± 2.5% and 96.2% ± 0.1% with final product productivity of 1.9 ± 0.0 g/L/h and 2.2 ± 0.0 g/L/h in RMG5 and RMG12, respectively. Moreover, ZML-pdc-ldh produced 32.9 ± 0.1 g/L D-lactate and 27.7 ± 0.2 g/L ethanol as well as 42.8 ± 0.0 g/L D-lactate and 53.1 ± 0.7 g/L ethanol with 97.1% ± 0.0% and 99.1% ± 0.8% carbon conversion rate using 20% molasses or corncob residue hydrolysate, respectively. Our study thus demonstrated that it is effective for lactate production by fermentation condition optimization and metabolic engineering to strengthen heterologous ldh expression while reducing the native ethanol production pathway. The capability of recombinant lactate-producer of Z. mobilis for efficient waste feedstock conversion makes it a promising biorefinery platform for carbon-neutral biochemical production.

A new class of near-infrared (NIR) reflectance pigments based on Co1−xMgxCr2−yAlyO4 (x = 0–1 and y = 0–2) was synthesised using the Pechini-type sol-gel process. The developed powders were characterised by thermogravimetry and differential scanning calorimetry, X-ray diffraction (XRD), ultraviolet–visible near-infrared diffuse reflectance spectroscopy, and colour Commission Internationale del'Eclairage (CIE) 1976 (L*a*b*) colour scales. The XRD patterns revealed characteristic peaks of the spinel structure with good crystallinity. Substituting Mg2+ for Co2+ ions in the tetrahedral positions and Al3+ for Cr3+ ions in the octahedral positions of CoCr2O4 reduces the cost and changes the colour of the pigment (green to yellow and then blue). Moreover, the synthesised pigments exhibited high NIR solar reflectance in the 780–2,500 nm wavelength range. The thermal and chemical stability of the pigments was also studied. Our findings demonstrate the potential for applying these pigments in cool colourants.

Heterostructure construction and heteroatom doping are powerful strategies for enhancing the electrolytic efficiency of electrocatalysts for overall water splitting. Herein, we present a P-doped MoS2/Ni3S2 electrocatalyst on nickel foam (NF) prepared using a one-step hydrothermal method. The optimized P[0.9mM]-MoS2/Ni3S2@NF exhibits a cluster nanoflower-like morphology, which promotes the synergistic electrocatalytic effect of the heterostructures with abundant active centers, resulting in high catalytic activity for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline electrolyte. The electrode exhibits low overpotentials and Tafel slopes for the HER and OER. In addition, the catalyst electrode used in a two-electrode system for overall water splitting requires an ultralow voltage of 1.42 V at 10 mA·cm−2 and shows no obvious increase in current within 35 h, indicating excellent stability. Therefore, the combination of P doping and the heterostructure suggests a novel path to formulate high-performance electrocatalysts for overall water splitting.

Electrode materials are the key to the electrochemical performance of supercapacitors. This study reports the electrochemical properties of V2O5 supercapacitors. V2O5 nanosheets with different morphologies were prepared by controlling the solvent under a facile hydrothermal method. The phase and the morphology of the samples were characterized by x-ray diffraction and scanning electron microscopy. The electrochemical properties of V2O5 nanosheets with different morphologies were studied by cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy. The charge transfers resistance decreases from 3.2 Ω of V2O5 particles to 2.0 Ω of V2O5 nanosheets. V2O5 nanosheets exhibit higher specific capacity (375 F g−1) than V2O5 particles (318 F g−1) in K2SO4 solution. The cycling capacity retention keeps 96.8% for 1000 cycles at 0.5 A g−1 in K2SO4 solution, indicating better cycling stability.

Biorefinery to produce value-added biochemicals offers a promising alternative to meet our sustainable energy and environmental goals. Acetoin is widely used in the food and cosmetic industries as taste and fragrance enhancer. The generally regarded as safe (GRAS) bacterium Zymomonas mobilis produces acetoin as an extracellular product under aerobic conditions. In this study, metabolic engineering strategies were applied including redistributing the carbon flux to acetoin and manipulating the NADH levels. To improve the acetoin level, a heterologous acetoin pathway was first introduced into Z. mobilis, which contained genes encoding acetolactate synthase (Als) and acetolactate decarboxylase (AldC) driven by a strong native promoter Pgap. Then a gene encoding water-forming NADH oxidase (NoxE) was introduced for NADH cofactor balance. The recombinant Z. mobilis strain containing both an artificial acetoin operon and the noxE greatly enhanced acetoin production with maximum titer reaching 8.8 g/L and the productivity of 0.34 g∙L−1∙h−1. In addition, the strategies to delete ndh gene for redox balance by native I-F CRISPR-Cas system and to redirect carbon from ethanol production to acetoin biosynthesis through a dcas12a-based CRISPRi system targeting pdc gene laid a foundation to help construct an acetoin producer in the future. This study thus provides an informative strategy and method to harness the NADH levels for biorefinery and synthetic biology studies in Z. mobilis.

Abstract Background Efficient and convenient genome-editing toolkits can expedite genomic research and strain improvement for desirable phenotypes. Zymomonas mobilis is a highly efficient ethanol-producing bacterium with a small genome size and desirable industrial characteristics, which makes it a promising chassis for biorefinery and synthetic biology studies. While classical techniques for genetic manipulation are available for Z. mobilis, efficient genetic engineering toolkits enabling rapidly systematic and high-throughput genome editing in Z. mobilis are still lacking. Results Using Cas12a (Cpf1) from Francisella novicida, a recombinant strain with inducible cas12a expression for genome editing was constructed in Z. mobilis ZM4, which can be used to mediate RNA-guided DNA cleavage at targeted genomic loci. gRNAs were then designed targeting the replicons of native plasmids of ZM4 with about 100% curing efficiency for three native plasmids. In addition, CRISPR–Cas12a recombineering was used to promote gene deletion and insertion in one step efficiently and precisely with efficiency up to 90%. Combined with single-stranded DNA (ssDNA), CRISPR–Cas12a system was also applied to introduce minor nucleotide modification precisely into the genome with high fidelity. Furthermore, the CRISPR–Cas12a system was employed to introduce a heterologous lactate dehydrogenase into Z. mobilis with a recombinant lactate-producing strain constructed. Conclusions This study applied CRISPR–Cas12a in Z. mobilis and established a genome editing tool for efficient and convenient genome engineering in Z. mobilis including plasmid curing, gene deletion and insertion, as well as nucleotide substitution, which can also be employed for metabolic engineering to help divert the carbon flux from ethanol production to other products such as lactate demonstrated in this work. The CRISPR–Cas12a system established in this study thus provides a versatile and powerful genome-editing tool in Z. mobilis for functional genomic research, strain improvement, as well as synthetic microbial chassis development for economic biochemical production.

Recent research on organic semiconductors has revealed that the composition of the constituent organic material, as well as the subtle changes in its structure (the stacking order of molecules), can noticeably affect its bulk properties. One of the reasons for this is that the charge transport in conjugated materials is strongly affected by their structure. Further, the charge mobility increases significantly when the conjugated materials exhibit self-assembly, resulting in the formation of ordered structures. However, well-organized nanostructures are difficult to obtain using classical solution processing methods, owing to their disordered state. A simple strategy for obtaining well-ordered material films involves synthesizing new conjugated materials that can self-organize. Introducing hydrogen bonding in the materials to yield hydrogen-bonded material superstructures can be a suitable method to fulfill these critical requirements. The formed hydrogen bonds will facilitate the assembly of the molecules into a highly ordered structure and bridge the distance between the adjacent molecules, thus enhancing the intermolecular charge transfer. In this minireview, hydrogen-bonded small molecules and polymers as well as the relationship between their chemical structures and performances in organic field-effect transistors are discussed.

Amyotrophic lateral sclerosis (ALS) is a rapidly progressive and highly fatal neurodegenerative disease. Although the pathogenesis of ALS remains unclear, increasing evidence suggests that a key contributing factor is mitochondrial dysfunction. Mitochondria are organelles in eukaryotic cells responsible for bioenergy production, cellular metabolism, signal transduction, calcium homeostasis, and immune responses and the stability of their function plays a crucial role in neurons. A single disorder or defect in mitochondrial function can lead to pathological changes in cells, such as an impaired calcium buffer period, excessive generation of free radicals, increased mitochondrial membrane permeability, and oxidative stress (OS). Recent research has also shown that these mitochondrial dysfunctions are also associated with pathological changes in ALS and are believed to be commonly involved in the pathogenesis of the disease. This article reviews the latest research on mitochondrial dysfunction and its impact on the progression of ALS, with specific attention to the potential of novel therapeutic strategies targeting mitochondrial dysfunction.

In this paper, a method of power system equipment recognition based on image processing is proposed. Firstly, we carry out wavelet transform on the sound signal of power system equipment collected from the site, and obtain the wavelet coefficient–time diagram. Then, the similarity of wavelet coefficients–time images of different equipment and the same equipment in different periods is calculated, which is used as the basis of the feasibility of image recognition. Finally, we select the HOG features of the image, and classify the selected features using SVM classifier. The method proposed in this paper can accurately identify and classify power system equipment through sound signals, and is different from the traditional method of classifying sound signals directly. The advantages of image processing can be effectively utilized through image processing to avoid the limitations of sound signal processing.

Ag-doped ZnO nanorods growth on a PET-graphene substrate (Ag-ZnO/PET-GR) with different Ag-doped content were synthesized by low-temperature ion-sputtering-assisted hydrothermal synthesis method. The phase composition, morphologies of ZnO, and electrical properties were analyzed. Ag-doping affects the initially perpendicular growth of ZnO nanorods, resulting in oblique growth of ZnO nanorods becoming more obvious as the Ag-doped content increases, and the diameter of the nanorods decreasing gradually. The width of the forbidden band gap of the ZnO films decreases with increasing Ag-doped content. For the Ag-ZnO/PET-GR composite structure, the Ag-ZnO thin film with 5% Ag-doped content has the largest carrier concentration (8.1 × 1018 cm−3), the highest mobility (67 cm2 · V−1 · s−1), a small resistivity (0.09 Ω·cm), and impressive electrical properties.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that affects upper and lower motor neurons. As there is no effective treatment for ALS, it is particularly important to screen key gene therapy targets. The identifications of microRNAs (miRNAs) have completely changed the traditional view of gene regulation. miRNAs are small noncoding single-stranded RNA molecules involved in the regulation of post-transcriptional gene expression. Recent advances also indicate that miRNAs are biomarkers in many diseases, including neurodegenerative diseases. In this review, we summarize recent advances regarding the mechanisms underlying the role of miRNAs in ALS pathogenesis and its application to gene therapy for ALS. The potential of miRNAs to target diverse pathways opens a new avenue for ALS therapy.

Mobile crowdsensing has emerged as an efficient paradigm for performing large-scale sensing tasks. Improving both the quantity and quality of users is still the pivotal problem for mobile crowdsensing system. This paper gives a comprehensive solution to improve the quantity and quality of users simultaneously through the social mobile crowdsensing architecture. To incentive the users based on the novel architecture, we first propose a universal initial diffuser selection algorithm to accommodate two widely studied diffusion models and, then a lightweight, multi-metric comprehensive, and parameter-free user quality evaluation method is presented. Finally, we propose a reverse auction to optimize the new criterion, which takes both social cost and user quality into consideration. Through both rigorous theoretical analysis and extensive simulations, we demonstrate that the proposed incentive mechanisms achieve computational efficiency, individual rationality, truthfulness, and guaranteed approximation. Meanwhile, the proposed incentive mechanisms show prominent advantage in total unit quality cost and running time.

Nanocoating combines the protective properties of conventional coating system with effects on nanoscale such as high hardness, UV scattering, and uniform dispersing. Their facile and low-cost synthesis, together with superior protective properties and multi-functionalities, makes nanocoating attractive candidates for next-generation coating systems. In this review, a brief introduction regarding mainstream nanocoating and its related challenges including the zinc oxide-, titanium dioxide-, silica dioxide-, graphene-, carbon nanotube-based nanocoating system is presented. Finally, a perspective of the nanocoating is demonstrated.

The pathogenesis of contrast-induced acute kidney injury (CI-AKI) is incompletely understood. MicroRNAs (miRNAs) are important mediators that normally function via post-transcriptional degradation of target mRNAs. Emerging evidence indicates the appearance of differentially expressed (DE) miRNAs in CI-AKI following the injection of intravenous contrast medium. However, there are differences in the pathological mechanism and incidence of CI-AKI between intravenous and intra-arterial contrast administration. The present study aimed to investigate the critical roles of dysregulated miRNAs and their associated mRNAs in kidney injury following intra-arterial contrast medium exposure. Based on a reliable CI-AKI rat model, we conducted genome-wide miRNA and mRNA expression profiling analysis using deep sequencing. In the study, 36 DE mature miRNAs were identified (fold change > 1.5 and p value < 0.05) in the kidneys of CI-AKI rats (n = 3) compared with that in the controls (n = 3), consisting of 23 up-regulated and 13 down-regulated DE miRNAs. Bioinformatic analysis revealed that wingnut (Wnt), transforming growth factor beta (TGF-β), and 5'-AMP-activated protein kinase (AMPK) signaling pathways were most likely to be modulated by these dysregulated miRNAs. Around 453 dysregulated genes (fold change > 2.0 and p value < 0.05) were identified. Integrated analysis revealed 2037 putative miRNA-mRNA pairs with negative correlations. Among them, 6 DE miRNAs and 13 genes were selected for further quantitative real-time reverse transcription polymerase chain reaction validation (n = 6 for each group), and a good correspondence between the two techniques was observed. In conclusion, the present study provided evidence of miRNA-mRNA interactions in the development of kidney injury following an intra-arterial contrast injection. These findings provide insights into the underlying mechanisms of CI-AKI.

Wireless sensor networks have been widely used in a variety of commercial and military applications, which often require neighbor nodes to establish connection quickly. Due to high mobility of nodes, it is a challenging issue to reduce discovery delay. Most discovery designs are based on pairwise and fixed duty cycle, in which discovery is passively achieved when two nodes wake up at the same time. In order to further improve the efficiency of neighbor discovery in mobile sensor networks, this paper proposes an improved group-based neighbor discovery algorithm (IGND) which dynamically adjusts the nodes’ active time based on spatial properties. This paper describes the network model and the algorithm implementation in detail. Simulation results show that the improved algorithm has a good effect in reducing discovery latency and promoting discovery efficiency.