Tantalum-doped tin oxide thin films using hollow cathode gas flow sputtering technology.

SnO2 and tantalum doped SnO2 (TTO) thin films were prepared using reactive hollow cathode gas flow sputtering (GFS) on glass substrates. An in-situ heating process under vacuum preceded the sputtering. The resistivity of the tin oxide films was reduced to a remarkable low of 2.02 × 10-3 Ω cm, with a carrier concentration of 2.55 × 1020 cm-3 and a mobility of 12.11 cm2V-1s-1. As the substrate temperature increased, the film resistivity decreased. Notably, at a substrate temperature of 270 °C, the effect of Ta doping on the film resistivity and carrier concentration was significantly stronger compared to higher temperatures. Elevating the substrate temperature and Ta doping resulted in a lower refractive index (n). This effect was consistently strong at higher temperatures, attributed to the higher film-free carrier concentration (4.54 × 1020 cm-3) compared to lower temperatures (2.35 × 1020 cm-3). The film's structure was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and atomic force microscope (AFM). The preferred direction of film growth was discussed. The successful and reproducible fabrication of tin oxide films underscores the advantages of gas flow sputtering (GFS) technology. GFS offers stable operating conditions across various oxygen flow levels without requiring target oxidization control, as is required in magnetron sputtering when managing gas status and film quality.

The fluorescence mKate2 labeling as a visualizing system for monitoring small extracellular vesicles.

Small extracellular vesicles (sEVs) are nanosized vesicles enclosed in a lipid membrane released by nearly all cell types. sEVs have been considered as reliable biomarkers for diagnostics and effective carriers. Despite the clear importance of sEV functionality, sEV research faces challenges imposed by the small size and precise imaging of sEVs. Recent advances in live and high-resolution microscopy, combined with efficient labeling strategies, enable us to investigate the composition and behavior of EVs within living organisms. Here, a modified sEVs was generated with a near infrared fluorescence protein mKate2 using a VSVG viral pseudotyping-based approach for monitoring sEVs. An observed was made that the mKate2-tagged protein can be incorporated into the membranes of sEVs without altering their physical properties. In vivo imaging demonstrates that sEVs labeled with mKate2 exhibit excellent brightness and high photostability, allowing the acquisition of long-term investigation comparable to those achieved with mCherry labeling. Importantly, the mKate2-tagged sEVs show a low toxicity and exhibit a favorable safety profile. Furthermore, the co-expression of mKate2 and rabies virus glycoprotein (RVG) peptide on sEVs enables brain-targeted visualization, suggesting the mKate2 tag does not alter the biodistribution of sEVs. Together, the study presents the mKate2 tag as an efficient tracker for sEVs to monitor tissue-targeting and biodistribution in vivo.

Effects of FGF2/FGFR1 Pathway on Expression of A1 Astrocytes After Infrasound Exposure.

Two types of reactive astrocytes, A1 and A2 astrocytes, are induced following neuroinflammation and ischemia. In this study, we evaluated the effects of the fibroblast growth factor (FGF)2/FGF receptor (FGFR)1 pathway on A1 and A2 astrocytes in the rat hippocampus using double-labeling immunofluorescence following infrasound exposure. A1 astrocytes were induced in the CA1 region of the hippocampus after exposure to infrasound for 3 days. The number of microglial cells was also increased, and we investigated if these might be responsible for the reactivity of A1 astrocytes. Accordingly, expression levels of C3 and Iba-1, as markers of A1 astrocytes and microglial cells, respectively, were both up-regulated in rat hippocampus following infrasound exposure, as demonstrated by western blot. We also explored the effect of the FGF2/FGFR1 pathway on A1 astrocyte reactivity by pretreating rats with FGF2 or the specific FGFR1 antagonist, PD173074. A1 astrocytes were gradually down-regulated by activation of the FGF2/FGFR1 pathway and were up-regulated by inhibition of the FGF2/FGFR1 pathway after infrasound damage. These results further our understanding of the role of reactive astrocytes in infrasound-induced central nervous system injury and will thus facilitate the development of new treatments for these injuries.

Che-1 inhibits oxygen-glucose deprivation/reoxygenation-induced neuronal apoptosis associated with inhibition of the p53-mediated proapoptotic signaling pathway.

Accumulating evidence suggests that Che-1 is a strong antiapoptotic protein and can protect cells against various insults. However, whether Che-1 is involved in the protection of neurons against cerebral ischemia/reperfusion injury remains unclear. In this study, we aimed to investigate the potential role of Che-1 in regulating cerebral ischemia/reperfusion injury-induced neuronal injury using the oxygen-glucose deprivation and reoxygenation (OGD/R) model in vitro. We found that Che-1 expression was induced in neurons following OGD/R treatment. Functional experiments showed that Che-1 knockdown aggravated OGD/R-induced neuronal apoptosis. In contrast, Che-1 overexpression exerted a protective effect against OGD/R-induced neuronal apoptosis. Moreover, our results showed that the protective effect of Che-1 was associated with the inhibition of p53-mediated proapoptotic genes, including Puma, Noxa, and Bax. In addition, we showed that Che-1 impeded the transcript activity of p53 toward apoptosis. Taken together, our results indicate that Che-1 alleviates OGD/R-induced neuronal apoptosis in-vitro through inhibition of p53-mediated proapoptotic signaling. Our study suggests that Che-1 may serve as a potential therapeutic target for the treatment of cerebral ischemic/reperfusion injury in vivo.

Thermophilic production of polyhydroxyalkanoates by a novel Aneurinibacillus strain isolated from Gudao oilfield, China.

Polyhydroxyalkanoates (PHAs) are usually biosynthesized using mesophilic strains, but the fermentation processes often suffer from bacterial contamination. This work reports the screening of thermophilic bacteria capable of producing PHAs under elevated temperatures to reduce the contamination risk. Strain XH2 was isolated from an oilfield and identified as Aneurinibacillus sp. by morphology, physiological-biochemical characterization, and 16S rDNA phylogenetic analysis. This strain can produce PHA granules, which was detected by Nile red staining and transmission electron microscopic imaging. At 55 °C, 111.6 mg l(-1) of PHA was produced in a fermentation medium containing glucose, peptone, and yeast extract. If peptone was removed from the medium, the yield of PHA would be enhanced by 2.4 times. The main monomers of the PHA product were identified to be 3-hydroxybutyrate and 3-hydroxyvalerate with a molar ratio of 17.2:1 by gas chromatography-mass spectroscopy (GC-MS) and nuclear magnetic resonance analyses. Two minor homologues, 3-hydroxyoctanoate, and 3-hydroxy-4-phenylbutanoate, were tentatively identified by GC-MS as well. This is the first report of thermophilic PHA bacterial producer from the Firmicutes phylum.

Thermophilic fermentation of acetoin and 2,3-butanediol by a novel Geobacillus strain.

BACKGROUND: Acetoin and 2,3-butanediol are two important biorefinery platform chemicals. They are currently fermented below 40°C using mesophilic strains, but the processes often suffer from bacterial contamination. RESULTS: This work reports the isolation and identification of a novel aerobic Geobacillus strain XT15 capable of producing both of these chemicals under elevated temperatures, thus reducing the risk of bacterial contamination. The optimum growth temperature was found to be between 45 and 55°C and the medium initial pH to be 8.0. In addition to glucose, galactose, mannitol, arabionose, and xylose were all acceptable substrates, enabling the potential use of cellulosic biomass as the feedstock. XT15 preferred organic nitrogen sources including corn steep liquor powder, a cheap by-product from corn wet-milling. At 55°C, 7.7 g/L of acetoin and 14.5 g/L of 2,3-butanediol could be obtained using corn steep liquor powder as a nitrogen source. Thirteen volatile products from the cultivation broth of XT15 were identified by gas chromatography-mass spectrometry. Acetoin, 2,3-butanediol, and their derivatives including a novel metabolite 2,3-dihydroxy-3-methylheptan-4-one, accounted for a total of about 96% of all the volatile products. In contrast, organic acids and other products were minor by-products. α-Acetolactate decarboxylase and acetoin:2,6-dichlorophenolindophenol oxidoreductase in XT15, the two key enzymes in acetoin metabolic pathway, were found to be both moderately thermophilic with the identical optimum temperature of 45°C. CONCLUSIONS: Geobacillus sp. XT15 is the first naturally occurring thermophile excreting acetoin and/or 2,3-butanediol. This work has demonstrated the attractive prospect of developing it as an industrial strain in the thermophilic fermentation of acetoin and 2,3-butanediol with improved anti-contamination performance. The novel metabolites and enzymes identified in XT15 also indicated its strong promise as a precious biological resource. Thermophilic fermentation also offers great prospect for improving its yields and efficiencies. This remains a core aim for future work.

A novel 2,3-xylenol-utilizing Pseudomonas isolate capable of degrading multiple phenolic compounds.

This work characterized a novel 2,3-xylenol-utilizing Pseudomonas isolate XQ23. From 16S rRNA phylogenetic analysis, XQ23 was found to be a member of the Pseudomonas putida group. Most of its physiological characteristics also shared similarities to P. putida. Phenols were catabolized by the meta-cleavage pathway. The dependence of the specific growth rate on 2,3-xylenol concentration could be well fitted by the Haldane model, with the maximum occurring at the concentration around 180 mg l(-1). Kinetic parameters indicated that XQ23 was sensitive to 2,3-xylenol and had low affinity. Three patterns, i.e. constant, linear decline, and allometric decline, were proposed to describe the biomass yields of phenols during bacterial degradation and XQ23 under 2,3-xylenol culturing conditions followed the allometric pattern. In a mineral-salts medium supplemented with 180 mg l(-1) of 2,3-xylenol as the sole carbon and energy source, over 40% of 2,3-xylenol was turned into CO(2) to provide energy by complete oxidization.