Laser-Textured Hybrid Brass Pattern Array Surface for High-Efficiency Fog Collection.

Fog collection holds promise for addressing water shortage. However, the conventional fabrication of fog collection devices, normally chemical methods, suffers many challenges, such as complicated preparation and environmental issues. Herein, we proposed a green fabrication strategy to construct superhydrophobic/hydrophilic surfaces on the brass substrate via the combination of laser fabrication and heat treatment. The wettability of brass is directly dictated by the laser process parameters. The different superhydrophobic/hydrophilic hybrid pattern surface with a rectangular/triangular array was designed for an optimal fog collection performance. The maximum water collection efficiency of the prepared surface is measured up to 427.36 mg h-1 cm-2, which is 97% higher than that of the control sample. Furthermore, the surface can be folded into different forms to realize a flexible collector. We envision that our work provides a green fabrication strategy to construct a superwetting surface for highly efficient fog collection.

Bridging engineering of polymeric carbon nitride for boosting photocatalytic CO2 reduction.

The inherent electron localized heptazine structure of carbon nitride (CN) derived from intrinsic tertiary N (N3C) bridging structure makes the photogenerated charge separation rather difficult, which severely limits photocatalytic CO2 activity of CN. Therefore, modulation of N3C bridging structure of CN is highly desirable to enhance the charge separation efficiency of CN. Herein, we reported a novel thiophene-bridged CN (BTCN) with intramolecular donor-π-acceptor (D-π-A) systems synthesized by nucleophilic substitution and Schiff base reaction to improve the photogenerated charge separation efficiency. The experimental and density functional theory (DFT) results indicate that this BTCN exhibits a high π-electron delocalization range and enhanced photogenerated charge transfer efficiency, which mainly account for the enhanced photocatalytic activity. The optimal BTCN photocatalyst exhibits enhanced charge separation efficiency and higher photocatalytic CO2 reduction activity with a CO yield of 23.02 µmol·g-1·h-1, which was higher than those of CN and edge-modified CN (ETCN) counterpart. This work highlights the importance of regulation of π-electron delocalization for the design of highly active CN photocatalysts via the rational substitution of N3C bridging structure with π-spacer molecular linkages for photocatalytic CO2 reduction.

NiCoP-nanocubes-decorated CoSe2 nanowire arrays as high-performance electrocatalysts toward oxygen evolution reaction.

Designing effective, robust, and low-cost catalysts for oxygen evolution reaction (OER) is an urgent requirement yet challenging task in water electrolysis. In this study, a NiCoP-nanocubes-decorated CoSe2 nanowires arrays three-dimensional/two-dimensional (3D/2D) electrocatalyst (NiCoP-CoSe2-2) was developed for catalyzing OER via a combined selenylation, co-precipitation, and phosphorization method. The as-obtained NiCoP-CoSe2-2 3D/2D electrocatalyst exhibits a low overpotential of 202 mV at 10 mA cm-2 with a small Tafel slope of 55.6 mV dec-1, which is superior to most of reported CoSe2 and NiCoP-based heterogeneous electrocatalysts. Experimental analyses and density functional theory (DFT) calculations proof that the interfacial coupling and synergy between CoSe2 nanowires and NiCoP nanocubes are not only beneficial to strengthen the charge transfer ability and accelerate reaction kinetics, but also facilitate the optimization of interfacial electronic structure, thereby enhancing the OER property of NiCoP-CoSe2-2. This study offers insights for the investigation and construction of transition metal phosphide/selenide heterogeneous electrocatalyst toward OER in alkaline media and broadens the prospect of industrial applications in energy storage and conversion fields.

Enhancing bacterial cellulose production with hypoxia-inducible factors.

Komagataeibacter xylinus is an aerobic strain that produces bacterial cellulose (BC). Oxygen levels play a critical role in regulating BC synthesis in K. xylinus, and an increase in oxygen tension generally means a decrease in BC production. Fumarate nitrate reduction protein (FNR) and aerobic respiration control protein A (ArcA) are hypoxia-inducible factors, which can signal whether oxygen is present in the environment. In this study, FNR and ArcA were used to enhance the efficiency of oxygen signaling in K. xylinus, and globally regulate the transcription of the genome to cope with hypoxic conditions, with the goal of improving growth and BC production. FNR and ArcA were individually overexpressed in K. xylinus, and the engineered strains were cultivated under different oxygen tensions to explore how their overexpression affects cellular metabolism and regulation. Although FNR overexpression did not improve BC production, ArcA overexpression increased BC production by 24.0% and 37.5% as compared to the control under oxygen tensions of 15% and 40%, respectively. Transcriptome analysis showed that FNR and ArcA overexpression changed the way K. xylinus coped with oxygen tension changes, and that both FNR and ArcA overexpression enhanced the BC synthesis pathway. The results of this study provide a new perspective on the effect of oxygen signaling on growth and BC production in K. xylinus and suggest a promising strategy for enhancing BC production through metabolic engineering. KEY POINTS: • K. xylinus BC production increased after overexpression of ArcA • The young's modulus is enhanced by the ArcA overexpression • ArcA and FNR overexpression changed how cells coped with changes in oxygen tension.

[Regulating the structure of bacterial cellulose by altering the expression of bcsD using CRISPR/dCas9].

Gluconacetobacter xylinus is a primary strain producing bacterial cellulose (BC). In G. xylinus, BcsD is a subunit of cellulose synthase and is participated in the assembly process of BC. A series of G. xylinus with different expression levels of the bcsD gene were obtained by using the CRISPR/dCas9 technique. Analysis of the structural characteristics of BC showed that the crystallinity and porosity of BC changed with the expression of bcsD. The porosity varied from 59.95%-84.05%, and the crystallinity varied from 74.26%-93.75%, while the yield of BC did not decrease significantly upon changing the expression levels of bcsD. The results showed that the porosity of bacterial cellulose significantly increased, while the crystallinity was positively correlated with the expression of bcsD, when the expression level of bcsD was below 55.34%. By altering the expression level of the bcsD gene, obtaining BC with different structures but stable yield through a one-step fermentation of G. xylinus was achieved.

Anchoring RuSe2 on CoSe2 nanoarrays as a hybrid catalyst for efficient and robust oxygen evolution reaction.

Interface engineering is an effective strategy to regulate the oxygen adsorption strength and accelerate the kinetics of oxygen evolution reaction (OER) catalyst by using the synergistic effect and electronic coupling between different metals. However, the design and demonstration of efficient and strongly coupled interfaces remains a bottleneck in the progress of efficient and durable OER catalysts. Herein, we designedly anchored RuSe2 nanoparticles to CoSe2 nanosheet arrays support on nickel foam (NF) to fabricate a RuSe2-CoSe2 nanosheet arrays with robust structure and strong electron coupling. Co-MOF was used as a template to conduce Ru ion exchange and then the precursor was selenized at low temperature to obtain RuSe2 modified CoSe2 nanosheet arrays. Thanks to the strong electron coupling between Ru with Co and the unique nanoarray structure, RuSe2-CoSe2 exhibits excellent OER performance with ultra-low overpotential of 200 mV at current density of 10 mA cm-2, and the performance did not degrade significantly during 100 h of continuous operation. Furthermore, the assembledRuSe2-CoSe2 (+)//Pt/C (-) can reach 50 mA cm-2 in a two-electrode system with a low battery voltage of 1.61 V, which is superior to the commercial RuO2 (+)//Pt/C (-) (1.79 V) electrode. This work provides an effective avenue for the design of highly active and durable electrocatalysts.

Bacterial cellulose and its potential for biomedical applications.

Bacterial cellulose (BC) is an important polysaccharide synthesized by some bacterial species under specific culture conditions, which presents several remarkable features such as microporosity, high water holding capacity, good mechanical properties and good biocompatibility, making it a potential biomaterial for medical applications. Since its discovery, BC has been used for wound dressing, drug delivery, artificial blood vessels, bone tissue engineering, and so forth. Additionally, BC can be simply manipulated to form its derivatives or composites with enhanced physicochemical and functional properties. Several polymers, carbon-based nanomaterials, and metal nanoparticles (NPs) have been introduced into BC by ex situ and in situ methods to design hybrid materials with enhanced functional properties. This review provides comprehensive knowledge and highlights recent advances in BC production strategies, its structural features, various in situ and ex situ modification techniques, and its potential for biomedical applications.

Preparation and characterization of antibacterial bacterial cellulose/chitosan hydrogels impregnated with silver sulfadiazine.

Hydrogels with pH sensitivity and stable mechanical and antibacterial properties have many desirable qualities and broad applications. A hydrogel based on bacterial cellulose and chitosan, impregnated with silver sulfadiazine (<1% w/w), was prepared using glutaraldehyde as the crosslinking agent. The presence of SSd was confirmed by Fourier transform infrared spectroscopy. Micropore size, swelling ratio, pH- sensitivity, and gram positive and negative antibacterial properties were studied by disk diffusion and colony forming unit. X-ray diffraction confirmed the presence of amorphous and crystalline regions in the hydrogel matrix following addition of SSd. The elemental composition, morphology, and mechanical properties of the hydrogels were characterized. Incorporation of SSd into bacterial cellulose-chitosan hydrogels significantly improved their mechanical and antibacterial properties. The antibacterial activity against E. coli and S. aureus was evaluated and SSd-BC/Ch hydrogels are more toxic to S. aureus than to E. coli. We use FESEM to observe bacterial morphology before and after exposure to SSd-BC/Ch hydrogels. The BacLight LIVE/DEAD membrane permeability kit is used to evaluate the membrane permeability of bacteria. These antibacterial hydrogels have many promising applications in food packaging, tissue engineering, drug delivery, clinical, biotechnological, and biomedical fields.

Ammonia exposure causes lung injuries and disturbs pulmonary circadian clock gene network in a pig study.

Ammonia toxicity to respiratory system in pig faming is of particular concern, but the molecular mechanism remains still unclear. The present study was devoted to assess the impacts of the ammonia exposure on the lung tissues based on a pig study using 80 ppm ammonia exposing to piglets for different days. The histology analysis revealed ammonia exposure induced lung injury and inflammatory response, as indicated by epithelial-mesenchymal transition (EMT), significant thickening of alveolar septa, infiltration of inflammatory cells and excessive mucus production. The transcriptome analysis revealed many more up-regulated genes in exposure groups when compared with the control group, and these genes were significantly enriched in the GO term of extracellular exosome, proteolysis, and regulation of circadian rhythm. The study discovered the induction of seven genes (CRY2, CIART, CREM, NR1D1, NR1D2, PER1 and PER3) that encode repressors of circadian clock. One gene (ARNTL) that encodes activator of circadian clock was down-regulated after ammonia exposure. The results of this study suggest that ammonia exposure disturbed the pulmonary circadian clock gene expression, which may establish new evidence for further understanding the toxicity of ammonia to lungs.

Ammonia Exposure Induced Cilia Dysfunction of Nasal Mucosa in the Piglets.

As one of the main environmental stressors commonly found in closed pig houses, ammonia poses high risks to the well-being of humans and animals. This study is aimed at assessing the toxicity of ammonia exposure (80 ppm for 12 days) on the nasal mucosa in piglets. Firstly, we found that after ammonia exposure, the number of white blood cells significantly increased and the serum levels of cytokine IL-4 were significantly decreased. Then, histological analyses showed significant thickening of nasal mucosa and excessive mucus production in the exposure group. Finally, RNA-seq analyses demonstrated that the ammonia exposure disturbed the transcriptome of nasal mucosa which revealed 176 upregulated genes and 426 downregulated genes. GO and KEGG pathway enrichment analysis of the DEGs showed that the upregulated genes were mainly related to neutrophil chemotaxis and immune response, while 80 out of the 426 downregulated genes including CCDCs, CFAPs, DNAHs, and TEKTs were enriched in the microtubule cytoskeleton and cilium morphogenesis/movement. All these results indicated that ammonia exposure induces nasal mucosal hyperplasia and cilia dysfunction, as well as a systemic inflammatory response in piglets. These findings provide new evidence for understanding the damage mechanism of ammonia on the nasal mucosa.

Tailoring bacterial cellulose structure through CRISPR interference-mediated downregulation of galU in Komagataeibacter xylinus CGMCC 2955.

Diverse applications of bacterial cellulose (BC) have different requirements in terms of its structural characteristics. culturing Komagataeibacter xylinus CGMCC 2955, BC structure changes with alterations in oxygen tension. Here, the K. xylinus CGMCC 2955 transcriptome was analyzed under different oxygen tensions. Transcriptome and genome analysis indicated that BC structure is related to the rate of BC synthesis and cell growth, and galU is an essential gene that controls the carbon metabolic flux between the BC synthesis pathway and the pentose phosphate (PP) pathway. The CRISPR interference (CRISPRi) system was utilized in K. xylinus CGMCC 2955 to control the expression levels of galU. By overexpressing galU and interfering with different sites of galU sequences using CRISPRi, we obtained strains with varying expression levels of galU (3.20-3014.84%). By testing the characteristics of BC, we found that the porosity of BC (range: 62.99-90.66%) was negative with galU expression levels. However, the crystallinity of BC (range: 56.25-85.99%) was positive with galU expression levels; galU expression levels in engineered strains were lower than those in the control strains. Herein, we propose a new method for regulating the structure of BC to provide a theoretical basis for its application in different fields.

Permeation of Silver Sulfadiazine Into TEMPO-Oxidized Bacterial Cellulose as an Antibacterial Agent.

Surface oxidation of bacterial cellulose (BC) was done with the TEMPO-mediated oxidation mechanism system. After that, TEMPO-oxidized bacterial cellulose (TOBC) was impregnated with silver sulfadiazine (AgSD) to prepare nanocomposite membranes. Fourier transform infrared spectroscopy (FTIR) was carried out to determine the existence of aldehyde groups on BC nanofibers and X-ray diffraction (XRD) demonstrated the degree of crystallinity. FESEM analysis revealed the impregnation of AgSD nanoparticles at TOBC nanocomposites with the average diameter size ranging from 11 nm to 17.5 nm. The sample OBCS3 showed higher antibacterial activity against Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli by the disc diffusion method. The results showed AgSD content, dependent antibacterial activity against all tested bacteria, and degree of crystallinity increases with TOBC and AgSD. The main advantage of the applications of TEMPO-mediated oxidation to BC nanofibers is that the crystallinity of BC nanofibers is unchanged and increased after the oxidation. Also enhanced the reactivity of BC as it is one of the most promising method for cellulose fabrication and functionalization. We believe that the novel composite membrane could be a potential candidate for biomedical applications like wound dressing, BC scaffold, and tissue engineering.

Identification of Quorum-Sensing Molecules of N-Acyl-Homoserine Lactone in Gluconacetobacter Strains by Liquid Chromatography-Tandem Mass Spectrometry.

Many Gram-negative bacteria can regulate gene expression in a cell density-dependent manner via quorum-sensing systems using N-acyl-homoserine lactones (AHLs), which are typical quorum-sensing signaling molecules, and thus modulate physiological characteristics. N-acyl-homoserine lactones are small chemical molecules produced at low concentrations by bacteria and are, therefore, difficult to detect. Here, a biosensor system method and liquid chromatography-tandem mass spectrometry were combined to detect and assay AHL production. As demonstrated by liquid chromatography-tandem mass spectrometry, Gluconacetobacter xylinus CGMCC No. 2955, a Gram-negative acetic acid-producing bacterium and a typical bacterial cellulose (BC) biosynthesis strain, produces six different AHLs, including N-acetyl-homoserine lactone, N-butanoyl-homoserine lactone, N-hexanoyl-homoserine lactone, N-3-oxo-decanoyl-homoserine lactone, N-dodecanoyl-homoserine lactone, and N-tetradecanoyl-homoserine lactone. Gluconacetobacter sp. strain SX-1, another Gram-negative acetic acid-producing bacterium, which can synthesize BC, produces seven different AHLs including N-acetyl-homoserine lactone, N-butanoyl-homoserine lactone, N-hexanoyl-homoserine lactone, N-3-oxo-octanoyl-homoserine lactone, N-decanoyl-homoserine lactone, N-dodecanoyl-homoserine lactone, and N-tetradecanoyl-homoserine lactone. These results lay the foundation for investigating the relationship between BC biosynthesis and quorum-sensing systems.