In this work, we integrated Ag
3
PO
4
with Bi
4
Ti
3
O
12
to form Bi
4
Ti
3
O
12
/Ag
3
PO
4
heterojunction nanocomposites by an ion-exchange method. The as-prepared Bi
4
Ti
3
O
12
/Ag
3
PO
4
...composites were systematically characterized by means of XRD, SEM, TEM, BET, XPS, UV-vis DRS, EIS, PL spectroscopy, and photocurrent response. SEM, TEM, and XPS results demonstrate the creation of Bi
4
Ti
3
O
12
/Ag
3
PO
4
heterojunction with obvious interfacial interaction between Bi
4
Ti
3
O
12
and Ag
3
PO
4
. PL spectra, EIS spectra, and photocurrent responses reveal that the composites display an enhanced separation efficiency of photogenerated electron-hole pairs, which is due to the charge transfer between Bi
4
Ti
3
O
12
and Ag
3
PO
4
. Rhodamine B (RhB) was chosen as the target organic pollutant to evaluate its degradation behavior over Bi
4
Ti
3
O
12
/Ag
3
PO
4
composites under simulated sunlight irradiation. Compared to bare Bi
4
Ti
3
O
12
and Ag
3
PO
4
nanoparticles, the composites exhibit a significantly enhanced photocatalytic activity. The highest photocatalytic activity is observed for the 10% Bi
4
Ti
3
O
12
/Ag
3
PO
4
composite with 10% Bi
4
Ti
3
O
12
content, which is about 2.6 times higher than that of bare Ag
3
PO
4
. The photocatalytic mechanism involved was investigated and discussed in detail.
Background
The intestinal microbiota and its metabolites have been reported to play an important role in stroke. Gut microbiota–originating short‐chain fatty acids (SCFAs) modulate brain functions ...directly or indirectly through immune, endocrine, vagal, and other humoral pathways. However, relatively few investigations have evaluated the gut microbiome and SCFAs spectrum or their potential associations with stroke outcomes in acute ischemic stroke (AIS) patients with different stroke severities.
Methods
We used 16S rRNA gene sequencing and gas chromatography to compare the fecal microbial composition and SCFA spectrum between AIS patients (n = 140) and healthy controls (n = 92). Their associations with 90‐day poor functional outcomes were evaluated by logistic regression models.
Results
We found that the intestinal microbiota distinguished AIS patients from healthy controls. A lack of SCFAs‐producing bacteria and a low fecal SCFAs level defined dysbiosis in AIS patients, especially those with increased stroke severity. The SCFAs levels were negatively correlated with stroke severity and prognosis. Reduced SCFAs levels, especially acetate, were associated with an increased risk of 90‐day poor functional outcomes even after adjustments.
Conclusions
Dysbiosis of SCFAs‐producing bacteria and SCFAs in AIS patients increased the subsequent risk for poor functional outcomes, indicating that SCFAs could be potential prognostic markers and therapeutic targets for stroke.
Bi
2
WO
6
nanostructures were synthesized by a hydrothermal route, where the effect of various experimental parameters on the products was investigated. It is demonstrated that the sample morphology ...and size is highly dependent on the NaOH content (or pH value). At
C
NaOH
= 0–0.0175 mol (pH range of 1–4), the prepared samples present flower-like hierarchical microspheres which are constructed from thin nanosheets via the self-assembly process. The size of the hierarchical microspheres exhibits a decreasing trend with increasing the NaOH content, from 7 μm at
C
NaOH
= 0 mol to 1.5 μm at
C
NaOH
= 0.0175 mol. At
C
NaOH
= 0.03–0.0545 mol (pH: 5–9), the prepared samples exhibit irregular flake-like structures, and their size increases with the increase in NaOH content. At
C
NaOH
= 0.055–0.05525 mol (pH: 10–11), the prepared samples are composed of uniform sphere-like particles with an average size of 85 nm. Compared to the NaOH content, the reaction temperature and time has a relatively small effect on the product morphology and size. The photocatalytic activity of the samples was evaluated by degrading rhodamine B (RhB) under irradiation of simulated sunlight. Among these samples, the samples composed of flower-like hierarchical microspheres have relatively high photocatalytic activity. In particular, the microspheres prepared at
C
NaOH
= 0.01 mol exhibit the highest photocatalytic activity, and the degradation percentage reaches 99 % after 2 h of irradiation.
Acute ischemic stroke (AIS) is an atherothrombotic disease. Trimethylamine-N-oxide (TMAO), a gut microbiota-dependent metabolite, has been shown to be proatherogenic and prothrombotic. However, the ...involvement of TMAO in AIS remains unclear. This study aimed to observe the dynamic changes of TMAO in AIS patients and identify the prognostic value of TMAO for major ischemic events and unfavorable functional outcomes.
This study included 204 AIS patients and 108 healthy controls. Blood samples for TMAO analyses were drawn at admission, 2 and 7 days of admission. Logistic regression models and receiver operating characteristic curves were established to identify associations between TMAO levels and major ischemic events (ischemic stroke, myocardial infarction, or death from an ischemic vascular event), as well as unfavorable functional outcomes (modified Rankin Scale score ≥3), at 90 days and 12 months.
TMAO levels showed no significant changes before and within 24 h of AIS treatment (at admission) but decreased significantly thereafter. Elevated log
-transformed baseline TMAO levels were associated with increased risks of 90-day odds ratio (OR), 2.62; 95% confidence interval (CI), 1.55-4.45;
< 0.001 and 12-month (OR, 3.59; 95% CI, 2.12-6.09;
< 0.001) major ischemic events, as well as 90-day (OR, 2.89; 95% CI, 1.46-5.71;
= 0.002) and 12-month (OR, 2.58; 95% CI, 1.50-4.46;
= 0.001) unfavorable functional outcomes, after adjustments for confounding factors. The areas under curve of baseline TMAO levels for predicting 90-day and 12-month major ischemic events were 0.72 (95% CI, 0.61-0.83;
< 0.001) and 0.76 (95% CI, 0.66-0.85;
< 0.001). Baseline TMAO levels improved the prognostic accuracy of conventional risk factors, National Institutes of Health Stroke Scale (NIHSS) score and N-terminal B-type natriuretic peptide (NT-proBNP) level.
TMAO levels decreased with time since stroke onset. Elevated TMAO levels at an earlier period portended poor stroke outcomes, broadening the potential clinical utility of TMAO as an independent prognostic marker and therapeutic target.
Rose flower-like Bi2WO6 hierarchical architectures with average diameter of 7 µm were synthesized via a hydrothermal route. The as-synthesized Bi2WO6 hierarchical architectures were decorated with Au ...nanoparticles (20–110 nm in size) by a photocatalytic reduction method. The prepared samples were systematically investigated by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, ultraviolet–visible diffuse reflectance spectroscopy, electrochemical impedance spectroscopy and photocurrent response. The photocatalytic performance of the samples was evaluated by the degradation of RhB in aqueous solution under simulated sunlight irradiation. It is observed that Au–Bi2WO6 composite exhibits a photocatalytic activity much higher (about 2.7 times higher) than that of bare Bi2WO6. The enhanced photocatalytic activity of Au–Bi2WO6 can be attributed to the enhanced separation of photogenerated electron–hole pairs due to the electron migration from Bi2WO6 hierarchical architectures to Au nanoparticles. As a result, more electrons and holes are able to participate in the photocatalytic reactions. The underlying photocatalytic mechanism was discussed.
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•Two types of g-C3N4/Bi4Ti3O12 p-n heterostructures were prepared.•One is constructed from Bi4Ti3O12 (BTO) nanoparticles and g-C3N4 nanosheets (NS).•The other is constructed from BTO ...nanoparticles and g-C3N4 nanoparticles (NP).•The composites exhibit photocatalytic activity higher than bare BTO and g-C3N4.•g-C3N4(NP)/BTO possess photocatalytic activity higher than g-C3N4(NS)/BTO.
Two types of g-C3N4/Bi4Ti3O12 p-n heterostructures were prepared by a simple mixing–calcining method. One is constructed from Bi4Ti3O12 (BTO) nanoparticles and g-C3N4 nanosheets (NS), and the other is constructed from BTO nanoparticles and g-C3N4 nanoparticles (NP). The structures, morphologies, optical and electrochemical properties of the samples were systematically characterized. PL spectra, EIS spectra and photocurrent responses demonstrate an effective separation of photogenerated electron-hole pairs for the composites. The photocatalytic performance of the composites was evaluated by the degradation of rhodamine B (RhB) under simulated-sunlight irradiation, revealing that they exhibit an enhanced photocatalytic activity compared to bare BTO and g-C3N4. The highest photocatalytic activity is observed for the composites with g-C3N4 content centered around 10%. Furthermore, g-C3N4(NP)/BTO composites integrated from BTO and g-C3N4 nanoparticles possess a superior photocatalytic activity compared to those integrated from BTO nanoparticles and g-C3N4 nanosheents.
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•Large-sized Bi4Ti3O12 square nanosheets were synthesized.•The nanosheets have nearly 100% exposed (010) facet.•The photocatalytic activity of the nanosheets was evaluated by ...degrading RhB.•The nanosheets exhibit photocatalytic activity much higher than nanoparticles.•The (010) facet has much higher surface energy than (100) and (101) facets.
In this work, large-sized Bi4Ti3O12 square nanosheets with highly exposed (010) facet were synthesized by a hydrothermal route. It is demonstrated that the lateral size of Bi4Ti3O12 square nanosheets reaches as large as 14 μm, while their average thickness is only about 60 nm, implying that the nanosheets have nearly 100% exposed (010) facet. The photocatalytic activity of Bi4Ti3O12 nanosheets was evaluated by RhB under simulated sunlight irradiation, revealing that they exhibit an excellent photocatalytic activity. The highly photocatalytic activity of the (010) facet can be ascribed to the fact that photogenerated electrons and holes are readily separated along the 010 direction and migrate to the (010) facet under the action of the polarization electric field, and moreover, the electronic structure calculations revel that the surface energy of the (010) facet is much larger than those of other facets like (100) and (101) facets.
In this work, we attempted to assemble Au and Ag nanoparticles (NPs) with different sizes onto Bi
4
Ti
3
O
12
(BTO) nanosheets with the aim of synergistically enhancing the photocatalytic ...performance. The as-prepared Au–Ag@BTO composite was systematically characterized by means of TEM, XRD, XPS, FTIR, UV–vis DRS, PL spectroscopy, EIS and photocurrent spectroscopy. The TEM observation demonstrates that larger-sized Au NPs (average size: 20 nm) and smaller-sized Ag NPs (average size: 8 nm) are uniformly decorated on the surface of BTO nanosheets. Compared to bare BTO, the Au–Ag@BTO composite manifests an increased visible light absorption, increased bandgap, increased photocurrent density, decreased charge-transfer resistance and decreased PL intensity. Separately using simulated sunlight, UV light and visible light as the light source, the photocatalytic performance of the composite was evaluated by the degradation of RhB. An enhanced photocatalytic performance of the composite is observed in all the cases. Under UV irradiation, the photocatalytic enhancement is mainly ascribed to the efficient separation of photogenerated electron/hole pairs caused by the smaller-sized Ag NPs, whereas the photocatalytic enhancement under visible light irradiation is dominantly due to the LSPR effects of the larger-sized Au NPs. The synergistic photocatalytic enhancement between Ag and Au NPs is achieved under simulated sunlight irradiation. Active species trapping experiments were carried out, revealing that photogenerated holes and ·O
2
−
radicals play a dominant and secondary role in the photocatalysis, respectively.
Facilitating the separation of photogenerated electron/hole pairs and widening the light-responsive region are crucial to enhance the overall photocatalytic performance of photocatalysts. To achieve ...this aim, here we have prepared Ag
S/Bi
Ti
O
heterojunction composite photocatalysts by assembling Ag
S quantum dots onto the surface of Bi
Ti
O
nanosheets. Transmission electron microscopy observation demonstrates that two types of Ag
S quantum dots separately with size of 40-70 and 7-17 nm are uniformly assembled onto the surface of large-sized Bi
Ti
O
thin nanosheets. The as-prepared Ag
S/Bi
Ti
O
heterojunction composites exhibit much enhanced light absorption (particularly in the visible and near-infrared region) and highly efficient separation of electrons and holes photogenerated in Bi
Ti
O
. Rhodamine B (RhB) aqueous solution was chosen as the target organic pollutant to evaluate the photocatalytic performance of the samples under simulated sunlight irradiation. It is found that the Ag
S/Bi
Ti
O
heterojunction composites manifest significantly enhanced photocatalytic activity toward the RhB degradaton. In particular, the 15wt% Ag
S/Bi
Ti
O
composite exhibits the highest photocatalytic activity, which is ca. 2.8 and 4.0 times higher than bare Bi
Ti
O
and Ag
S, respectively. The enhanced photocatalytic activity of the composites can be explained as a result of the Z-scheme electron transfer from the conduction band of Bi
Ti
O
to the valence band of Ag
S, and thus more photogenerated holes in the valence band of Bi
Ti
O
and electrons in the conduction band of Ag
S are able to participate in the photocatalytic reactions. Active species trapping experiments were carried out, from which it is concluded that photogenerated holes and •O
radicals play the dominant and secondary role in the photocatalysis, respectively.
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