Gas Dispersion Characteristics in a Novel Jet-Stirring Coupling Flotation Device.

A jet-stirring coupling flotation device (JSCFD) was proposed to analyze the distribution characteristics of gas holdup and bubble Sauter mean diameter (D 32) in a gas-liquid system under various parameters. Results of studies suggested that the gas holdup increased with methyl isobutyl carbinol concentration, feeding pressure, and gas flow rate. The maximal gas holdup in the absence of the stirring impeller was ∼23.29% for the bubble size of 0.59 mm, which was considerably lower than the maximum gas holdup of 66.27% for the bubble size of 0.31 mm in the presence of the stirring impeller; the gas holdup was raised by ∼43% due to the bubbles torn by the stirring impeller to generate extensive smaller size bubbles and increase the content of small bubbles, and increasing the stirring impeller speed was conducive to reduce the bubble size and increase the gas holdup in JSCFD. Compared to traditional flotation machines, the size of bubbles generated by JSCFD was smaller, and the gas holdup distribution conforms to the following order: JSCFD > mechanical flotation machine > column flotation, which demonstrated that the JSCFD had a noticeable effect on increasing the gas holdup and reducing the bubble size.

Monitoring G-Quadruplex Formation with DNA Carriers and Solid-State Nanopores.

G-quadruplexes (Gqs) are guanine-rich DNA structures formed by single-stranded DNA. They are of paramount significance to gene expression regulation, but also drug targets for cancer and human viruses. Current ensemble and single-molecule methods require fluorescent labels, which can affect Gq folding kinetics. Here we introduce, a single-molecule Gq nanopore assay (smGNA) to detect Gqs and kinetics of Gq formation. We use ∼5 nm solid-state nanopores to detect various Gq structural variants attached to designed DNA carriers. Gqs can be identified by localizing their positions along designed DNA carriers, establishing smGNA as a tool for Gq mapping. In addition, smGNA allows for discrimination of (un)folded Gq structures, provides insights into single-molecule kinetics of Gq folding, and probes quadruplex-to-duplex structural transitions. smGNA can elucidate the formation of Gqs at the single-molecule level without labeling and has potential implications on the study of these structures both in single-stranded DNA and in genomic samples.

Pretreatment with Cholecalciferol Alleviates Renal Cellular Stress Response during Ischemia/Reperfusion-Induced Acute Kidney Injury.

BACKGROUND: Cellular stress is involved in ischemia/reperfusion- (I/R-) induced acute kidney injury (AKI). This study is aimed at investigating the effects of pretreatment with cholecalciferol on renal oxidative stress and endoplasmic reticulum (ER) stress during I/R-induced AKI. METHODS: I/R-induced AKI was established by cross-clamping renal pedicles for 90 minutes and then reperfusion. In the Chol + I/R group, mice were orally administered with three doses of cholecalciferol (25 µg/kg) at 1, 24, and 48 h before ischemia. Renal cellular stress and kidney injury were measured at different time points after reperfusion. RESULTS: I/R-induced AKI was alleviated in mice pretreated with cholecalciferol. In addition, I/R-induced renal cell apoptosis, as determined by TUNEL, was suppressed by cholecalciferol. Additional experiment showed that I/R-induced upregulation of renal GRP78 and CHOP was inhibited by cholecalciferol. I/R-induced renal IRE1α and eIF2α phosphorylation was attenuated by cholecalciferol. Moreover, I/R-induced renal GSH depletion, lipid peroxidation, and protein nitration were blocked in mice pretreated with cholecalciferol. I/R-induced upregulation of renal NADPH oxidases, such as p47phox, gp91phox, and nox4, was inhibited by cholecalciferol. I/R-induced upregulation of heme oxygenase- (HO-) 1, gshpx and gshrd, was attenuated in mice pretreated with cholecalciferol. CONCLUSIONS: Pretreatment with cholecalciferol protects against I/R-induced AKI partially through suppressing renal cellular stress response.

Early Unclamping Laparoscopic Partial Nephrectomy for Complex Renal Tumor: Data from a Chinese Cohort.

OBJECTIVE: To evaluate the efficacy and safety of early unclamping laparoscopic partial nephrectomy (LPN) for complex renal tumor relative to the standard artery clamping technique (SCT). METHODS: Sixty-one patients with complex renal tumor (RENAL score ≥7) underwent LPN at our institution from January 2013 to April 2017. LPN was performed via SCT in 32 patients and via the early unclamping technique (EUT) in 29 patients. Operation time, warm ischemia time (WIT), blood loss, bleeding requiring transfusion, tumor volume, excisional volume loss (EVL), complications, and renal function before and after operation of the affected kidney were compared between the groups. RESULTS: All surgeries were successful without conversion to open or nephrectomy. EUT reduced the WIT (p < 0.001) but did not increase the complication rate (p = 0.322). Although the tumor volume and EVL were larger in the EUT than in the SCT group (p = 0.011, p = 0.001), glomerular filtration rate (GFR) reduction in the affected kidney did not significantly differ between the groups (p = 0.120). CONCLUSION: Early unclamping LPN for complex renal tumor is safe and efficient. Additionally, the EUT could expand the application of LPN in complex renal tumors, and make this challenging surgery easier and safer.

Engineering DNA Three-Way Junction with Multifunctional Moieties: Sensing Platform for Bioanalysis.

Functionalization of DNA nanostructures is critical to the achievement of the application in biosensors. Herein, we demonstrate a novel DNA three-way junction (TWJ) with three functional moieties, which integrates the electrochemical, fluorescent, and colorimetric properties. Upon addition of external stimuli, including DNA, thrombin, and ATP, the specific interactions between targets and sensing elements could induce strand displacement reaction and conformation transformation, resulting in the integration of G-quadruplex/hemin complex as electrochemical probe, lighting up the fluorescence of DNA/Ag nanoclusters and enhancing the catalytic activity of DNAzyme to catalyze the H2O2-TMB system to generate colorimetric signal. Such a functional DNA nanostructure actually serves as a biosensing platform, showing high sensitivity and selectivity for DNA, thrombin, and ATP detection. Furthermore, We also show that this novel sensing platform can be utilized to detect three different kinds of targets independently and simultaneously. Our integrated concept provides a paradigm for exploring the potential of TWJs in analytical applications.

G-quadruplex enhanced fluorescence of DNA-silver nanoclusters and their application in bioimaging.

Guanine proximity based fluorescence enhanced DNA-templated silver nanoclusters (AgNCs) have been reported and applied for bioanalysis. Herein, we studied the G-quadruplex enhanced fluorescence of DNA-AgNCs and gained several significant conclusions, which will be helpful for the design of future probes. Our results demonstrate that a G-quadruplex can also effectively stimulate the fluorescence potential of AgNCs. The major contribution of the G-quadruplex is to provide guanine bases, and its special structure has no measurable impact. The DNA-templated AgNCs were further analysed by native polyacrylamide gel electrophoresis and the guanine proximity enhancement mechanism could be visually verified by this method. Moreover, the fluorescence emission of C3A (CCCA)4 stabilized AgNCs was found to be easily and effectively enhanced by G-quadruplexes, such as T30695, AS1411 and TBA, especially AS1411. Benefiting from the high brightness of AS1411 enhanced DNA-AgNCs and the specific binding affinity of AS1411 for nucleolin, the AS1411 enhanced AgNCs can stain cancer cells for bioimaging.

Molecular aptamer beacon tuned DNA strand displacement to transform small molecules into DNA logic outputs.

A molecular aptamer beacon tuned DNA strand displacement reaction was introduced in this work. This strand displacement mode can be used to transform the adenosine triphosphate (ATP) input into a DNA strand output signal for the downstream gates to process. A simple logic circuit was built on the basis of this mechanism.

Aptamer-based sensing platform using three-way DNA junction-driven strand displacement and its application in DNA logic circuit.

We proposed a new three-way DNA junction-driven strand displacement mode and fabricated an aptamer-based label-free fluorescent sensing platform on the basis of this mechanism. Assembling the aptamer sequence into the three-way DNA junction makes the platform sensitive to the target of the aptamer. A label-free signal readout method, split G-quadruplex enhanced fluorescence of protoporphyrin IX (PPIX), was used to report the final signal. Here, adenosine triphosphatase (ATP) was taken as a model and detected through this approach, and DNA strand could also be detected by it. The mechanism was investigated by native polyacrylamide gel electrophoresis. Furthermore, on the basis of this molecular platform, we built a logic circuit with ATP and DNA strands as input. Aptamer played an important role in mediating the small molecule ATP to tune the DNA logic gate. Through altering the aptamer sequence, this molecular platform will be sensitive to various stimuli and applied in a wide field.

Graphene-based aptamer logic gates and their application to multiplex detection.

In this work, a GO/aptamer system was constructed to create multiplex logic operations and enable sensing of multiplex targets. 6-Carboxyfluorescein (FAM)-labeled adenosine triphosphate binding aptamer (ABA) and FAM-labeled thrombin binding aptamer (TBA) were first adsorbed onto graphene oxide (GO) to form a GO/aptamer complex, leading to the quenching of the fluorescence of FAM. We demonstrated that the unique GO/aptamer interaction and the specific aptamer-target recognition in the target/GO/aptamer system were programmable and could be utilized to regulate the fluorescence of FAM via OR and INHIBIT logic gates. The fluorescence changed according to different input combinations, and the integration of OR and INHIBIT logic gates provided an interesting approach for logic sensing applications where multiple target molecules were present. High-throughput fluorescence imagings that enabled the simultaneous processing of many samples by using the combinatorial logic gates were realized. The developed logic gates may find applications in further development of DNA circuits and advanced sensors for the identification of multiple targets in complex chemical environments.