12 research outputs found
Effective Visible-Excited Charge Separation in Silicate-Bridged ZnO/BiVO<sub>4</sub> Nanocomposite and Its Contribution to Enhanced Photocatalytic Activity
It is highly desired to enhance the
visible-excited charge separation
of nanosized BiVO<sub>4</sub> for utilization in photocatalysis. Here
ZnO/BiVO<sub>4</sub> nanocomposites in different molar-ratios are
fabricated by simple wet-chemical processes, after synthesis of nanosized
BiVO<sub>4</sub> and ZnO by hydrothermal methods. It is shown by means
of atmosphere-controlled steady-state surface photovoltage spectra
and transient-state surface photovoltage responses that the photogenerated
charges of resulting nanocomposite shows longer lifetime and higher
separation than that of BiVO<sub>4</sub> alone. This leads to its
superior photoactivities for water oxidation to produce O<sub>2</sub> and for colorless pollutant degradation under visible irradiation,
with about three times enhancement. Interestingly, it is suggested
that the prolonged lifetime and enhanced separation of photogenerated
charges in the nanocomposite is attributed to the unusual spatial
transfer of visible-excited high-energy electrons, by visible radiation
from BiVO<sub>4</sub> to ZnO on the basis of the ultralow-temperature
electron paramagnetic resonance measurements and the photocurrent
action spectra. Moreover, it is clearly demonstrated that the photogenerated
charge separation of resulting ZnO/BiVO<sub>4</sub> nanocomposite
could be further enhanced after introducing the silicate bridges so
as to improve the visible photocatalytic activity greatly, attributed
to the built bridge favorable to charge transfer. This work would
provide a feasible way to enhance the solar energy utilization of
visible-response semiconductor photocatalysts
Enhancement Effects of Cobalt Phosphate Modification on Activity for Photoelectrochemical Water Oxidation of TiO<sub>2</sub> and Mechanism Insights
Cobalt
phosphate-modified nanocrystalline TiO<sub>2</sub> (nc-TiO<sub>2</sub>) films were prepared by a doctor blade method using homemade nc-TiO<sub>2</sub> paste, followed by the post-treatments first with monometallic
sodium orthophosphate solution and then with cobalt nitrate solution.
The modification with an appropriate amount of cobalt phosphate could
greatly enhance the activity for photoelectrochemical (PEC) water
oxidation of nc-TiO<sub>2</sub>, superior to the modification only
with the phosphate anions. It is clearly demonstrated that the enhanced
activity after cobalt phosphate modification is attributed to the
roles of cobaltÂ(II) ions linked by phosphate groups with the surfaces
of nc-TiO<sub>2</sub> mainly by means of the surface photovoltage
responses in N<sub>2</sub> atmosphere. It is suggested that the linked
cobaltÂ(II) ions could capture photogenerated holes effectively to
produce high-valence cobalt ions, further inducing oxidation reactions
with water molecules to rereturn to cobaltÂ(II) ions. This work is
useful to explore feasible routes to improve the performance of oxide-based
semiconductors for PEC water splitting to produce clean H<sub>2</sub> energy
Synthesis of Efficient Nanosized Rutile TiO<sub>2</sub> and Its Main Factors Determining Its Photodegradation Activity: Roles of Residual Chloride and Adsorbed Oxygen
Nanosized TiO<sub>2</sub> containing different contents
of rutile
phase was controllably synthesized by a hydrochloric acid-modified
hydrothermal process. It is demonstrated that the formation of rutile
phase in TiO<sub>2</sub> mainly depends on the role of chlorine anions
in the synthesis, and a certain amount of residual chloride would
exist on the surfaces of the resulting nanocrystalline rutile TiO<sub>2</sub>. Interestingly, the as-prepared rutile shows high activity
for photodegradation of rhodamine B dye compared with the as-prepared
anatase, even superior to the P25 TiO<sub>2</sub>. It is mainly attributed
to the residual chloride that could promote the dye adsorbed on the
surfaces of TiO<sub>2</sub>, consequently accelerating the photosensitization
oxidation reactions of the dye molecules. In the photodegradation
of liquid-phase phenol and gas-phase aldehyde, the as-prepared rutile
TiO<sub>2</sub> samples display low activity, which is attributed
to the photogenerated electrons weakly captured by the adsorbed oxygen,
since the residual chloride could effectively capture photoinduced
holes based on the atmosphere-controlled surface photovoltage spectroscopy
results. Further, the photoactivity of resulting rutile for degrading
phenol and aldehyde is greatly enhanced by modifying a proper amount
of phosphoric acids to increase the adsorption of O<sub>2</sub>, even
higher than that of the P25 TiO<sub>2</sub>. This work would explore
feasible routes to synthesize efficient nanosized rutile TiO<sub>2</sub>-based photocatalysts for degrading colored and colorless organic
pollutants by investigating the rate-determining factors in the photodegradation
processes
Expression Profiling of Preadipocyte MicroRNAs by Deep Sequencing on Chicken Lines Divergently Selected for Abdominal Fatness
<div><p>Through posttranscriptional gene regulation, microRNA (miRNA) is linked to a wide variety of biological processes, including adipogenesis and lipid metabolism. Although miRNAs in mammalian adipogenesis have been worked on extensively, their study in chicken adipogenesis is still very limited. To find miRNAs potentially important for chicken preadipocyte development, we compared the preadipocyte miRNA expression profiles in two broiler lines divergently selected for abdominal fat content, by sequencing two small RNA libraries constructed for primary preadipocytes isolated from abdominal adipose tissues. After bioinformatics analyses, from chicken miRNAs deposited in miRBase 20.0, we identified 225 miRNAs to be expressed in preadipocytes, 185 in the lean line and 200 in the fat line (derived from 208 and 203 miRNA precursors, respectively), which corresponds to 114 miRNA families. The let-7 family miRNAs were the most abundant. Furthermore, we validated the sequencing results of 15 known miRNAs by qRT-PCR, and confirmed that the expression levels of most miRNAs correlated well with those of Solexa sequencing. A total of 33 miRNAs was significantly differentially expressed between the two chicken lines (P<0.05). Gene ontology analysis revealed that they could target genes enriched in the regulation of gene transcription and chromatin function, response to insulin stimulation, and IGF-1 signaling pathways, which could have important roles in preadipocyte development. Therefore, a valuable information and resource of miRNAs on chicken adipogenesis were provided in this study. Future functional investigations on these miRNAs could help explore related genes and molecular networks fundamental to preadipocyte development.</p></div
Differentially expressed miRNAs.
<p>26 up-regulated miRNAs, and 7 down-regulated miRNAs in the fat chicken line. Fold-change (Y-axis) indicates in log2-scale the fold-changes between the number of reads of miRNAs in the fat chicken lines and the lean chicken line.</p
Expression level of 17 novel miRNAs validated.
<p>Note: * indicates the fold changes of 2<sup>-ΔCt</sup> values in the fat line against the lean line.</p><p>Expression level of 17 novel miRNAs validated.</p
qRT-PCR validation of miRNAs in the preadipocytes of the lean and fat chicken lines.
<p>miRNA expression levels were normalized, and were selected at high, intermediate and low levels according to their number of reads by Solexa sequencing. Seven miRNAs (gga-miR-148a, gga-miR-101, gga-miR-100, gga-miR-92, gga-miR-130a, gga-miR-19a and gga-miR-221) with significantly differential expression levels were found (* P<0.05; ** P<0.01). Inset shows the enlarged view of the five lowly expressed miRNAs.</p
The top 10 most abundantly expressed miRNAs.
<p>The top 10 most abundantly expressed miRNAs.</p
Number of reads and expression levels of the 15 miRNAs chosen for qRT-PCR validation.
<p>Number of reads and expression levels of the 15 miRNAs chosen for qRT-PCR validation.</p
Length distribution of small RNA read sequences in fat and lean chicken lines.
<p>Length distribution of small RNA read sequences in fat and lean chicken lines.</p