Origin of the High Density of Oxygen Vacancies at the Back Channel of Back-Channel-Etched a-InGaZnO Thin-Film Transistors.

This study reveals the pronounced density of oxygen vacancies (Vo) at the back channel of back-channel-etched (BCE) a-InGaZnO (a-IGZO) thin-film transistors (TFTs) results from the sputtered deposition rather than the wet etching process of the source/drain metal, and they are distributed within approximately 25 nm of the back surface. Furthermore, the existence and distribution depth of the high density of Vo defects are verified by means of XPS spectra analyses. Then, the mechanism through which the above Vo defects lead to the instability of BCE a-IGZO TFTs is elucidated. Lastly, it is demonstrated that the device instability under high-humidity conditions and negative bias temperature illumination stress can be effectively alleviated by etching and thus removing the surface layer of the back channel, which contains the high density of Vo defects. In addition, this etch method does not cause a significant deterioration in the uniformity of electrical characteristics and is quite convenient to implement in practical fabrication processes. Thus, a novel and effective solution to the device instability of BCE a-IGZO TFTs is provided.

High-Performance Osmotic Power Generators Based on the 1D/2D Hybrid Nanochannel System.

Extracting clean energy by converting the salinity gradient between river and sea into energy is an effective way to reduce the global pollution and carbon emissions. Reverse electrodialysis (RED) is of great importance to realize the energy conversion assisting the ion-selective membrane. However, its higher ion resistance and lower conversion efficiency results in the undesirable power conversion performance. Here, we demonstrate a 1D/2D hybrid nanochannel system to achieve high osmotic energy conversion and output power. This heterogeneous structure is composed of two structures, in which the subnanometer nanochannels in graphene oxide membrane (GOM) can serve as a selective layer and reduce the ion diffusion energy barrier, while the nanochannel in the polymer can introduce asymmetry to enhance ionic rectification and conversion efficiency. This heterogeneous membrane exhibits excellent cation selectivity and enhanced ionic current rectification (ICR) performance. The application of the GOM/PET hybrid nanochannel system in osmotic energy harvesting is evaluated, and the output power can reach up to 118.2 pW with the energy conversion efficiency of 40.3%. Theoretical calculation indicates that the 1D/2D hybrid system can effectively take the advantage of excellent cation selectivity of 2D lamellar nanochannels to improve its RED performance significantly.

Sinapine Thiocyanate Inhibits the Proliferation and Mobility of Pancreatic Cancer Cells by Up-Regulating GADD45A.

Background: Sinapine thiocyanate (ST), an alkaloid isolated from the seeds of cruciferous species, has exhibited anti-inflammatory, anti-malignancy, and anti-angiogenic effects in previous studies. However, the effects and molecular mechanisms of action of ST in pancreatic cancer (PC) are still limited. Materials and methods: PC cells were treated with different concentrations (0, 20, 40, and 80 µM) of ST. The proliferative ability of PC cells in vitro was determined using cell count kit-8 (CCK-8), 5-ethynyl-2' deoxyuridine, colony formation, and flow cytometry assays. The mobility of PC cells in vitro was analyzed using wound healing assay, transwell assay, Western blotting, and immunofluorescence. High-throughput sequencing followed by bioinformatics analysis, reverse-transcriptase quantitative polymerase chain reaction (RT-qPCR), and Western blotting were performed to identify the key targets of ST. Finally, CCK-8 assay, wound healing assay, and xenograft tumor model were used to determine the relationship between ST and growth arrest and DNA damage-inducible alpha (GADD45A; the key target of ST) and malignant biological properties of PC in vitro and in vivo. Results: ST significantly repressed the PC cell proliferation rate and colony formation in vitro and arrested cells in the G2/M phase. ST inhibited PC cell mobility in vitro and increased E-cadherin expression (an epithelial biomarker). GADD45A was considered the key target of ST in PC and was elevated in PC cells treated with ST. The inhibition of GADD45A significantly alleviated the suppressive effects of ST on PC cell proliferation and mobility in vitro. ST suppressed PC cell proliferation in vivo and increased GADD45A expression in tumor tissues. Conclusion: ST exhibited significant anti-tumor effects on PC cells by upregulating GADD45A. ST may be a potential drug for PC treatment.

Fast synthesis of gold nanostar SERS substrates based on ion-track etched membrane by one-step redox reaction.

Surface-enhanced Raman scattering (SERS), due to its high detecting sensitivity and rapid data acquisition ability, has been considered as a powerful technique for label-free ultrasensitive detection of chemical and biochemical analytes. As an important part, the uniform SERS substrate is the prerequisite for this technology being used in all the related areas. Therefore, seeking the fast, convenient and low-cost way to obtain the SERS substrate with high performance and reproducibility never stops in recent decades. In this work, the PC membrane with uniform nanopores obtained by ion irradiation and chemical etching (i.e., ion-track etched PC membrane) was first used to prepare the gold nanostar SERS substrate. The monolayer gold nanostars can be obtained through a one-step redox reaction on the surface of the PC membrane, which not only can act as the base of SERS substrate but also can work as the reaction adjuster. By optimizing the growth conditions, the SERS substrate with uniform monolayer gold nanostars can be fabricated without any complicated procedures and costly equipment fast (in 20 mins). Meanwhile, the prepared flexible gold nanostar SERS substrate exhibits excellent Raman performance, which can effectively detect the analyte R6G with the concentration as low as 1 × 10-10 M and the SERS enhancement factors can be around 3.70 × 105. The new facile SERS substrate preparation method is cost-effective, convenient, fast and easily scale up, which can satisfy the requests of the real applications in many fields.

Ionic Transport and Sieving Properties of Sub-nanoporous Polymer Membranes with Tunable Channel Size.

Bioinspired nanoporous membranes show great potential in ionic separation and water filtration by offering high selectivity with less permeation resistance. However, complex processes always limit their applications. Here, we report a convenient approach to introduce ionic selective channels in a micron-thick polycarbonate membrane through swift heavy ion irradiation accompanied by UV sensitization and pulsed-electrical etching. The characteristic dimension of channels was tuned through regulating energy loss of the incident ion and UV sensitization time of the membrane, resulting in the sub-nanoporous membranes with mean channel diameter ranging from <2.4 to 9.7 Å. These membranes showed the voltage-activated ionic transport properties associated with the dehydration effect, and the corresponding I-V characteristics were related to ionic strength, solution pH, ionic type, and channel diameter. It was found that the transmembrane conduction of multivalent ions was severely suppressed compared to monovalent ions, until the size of the membrane channel was comparable to the hydrated diameter of multivalent ions. Ionic sieving experiments also demonstrated the excellent ionic valence selectivity of the membrane. Even for the membrane with a channel diameter close to 1 nm, the Li+/Mg2+ separation ratio was still as high as 40, and an even higher separation ratio was found for Li+/La3+ (>3000).

A high-performance non-enzymatic electrochemical hydrazine sensor based on NiCo2S4 porous sphere.

A non-enzymatic electrochemical sensor-NiCo2S4/GCE was constructed for sensitive and selective detection of hydrazine (N2H4), which was designed based on porous nanostructure and synthesized through a facile hydrothermal method. The nanocomposite has been characterized using a series of characterizations such as X-ray powder diffraction (XRD), scanning electron microscopic (SEM), transmission electron microscopy (TEM), showing the porous NiCo2S4 sphere was made of interconnected nanoparticles with porous structure. Electrochemical measurements revealed that the porous NiCo2S4 sphere based sensor exhibited an excellent voltammetric response towards the N2H4 oxidation with a wide linear range of 1.7 µM to 7.8 mM, a low detection limit of 0.6 µM (S/N = 3), a sensitivity of 179.1 µA mM-1 cm-2. Moreover, determinations of N2H4 in tap water samples were carried out by standard addition. Acceptable results with relative standard deviation of 2.1-3.0% and recovery of 95.20-103.6% were obtained for five parallel measurements. Therefore, NiCo2S4/GCE promised to be a new platform for electrochemical detection of N2H4.

Selectively Enhanced Ion Transport in Graphene Oxide Membrane/PET Conical Nanopore System.

Graphene oxide (GO) has become a promising 2D material in many areas, such as gas separation, seawater desalination, antibacterial materials, and so on because of its abundant oxygen-containing functional groups and excellent dispersibility in various solvents. The graphene oxide membrane (GOM), a laminar and channel-rich structure assembled by stacked GO nanosheets, served as a kind of precise and ultrafast separation material has attracted widespread attention in membrane separation field. To break the trade-off between ion permeability and ion selectivity of separation membrane based on GOM, GOM/conical nanopore system is obtained by spin-coating ultrathin GOM on PET conical nanopore, which possesses ion rectification property. Comparing to pure PET conical nanopore, the existence of GOM not only enhances the cation conductance but also makes the ion rectification ratio increase from 4.6 to 238.0 in KCl solution. Assisted by COMSOL simulation, it is proved that the GOM can absorb large amount of cations and act as cation source to improve the ion selectivity and rectification effect of GOM/conical nanopore system. Finally, the chemical stability of GOM/conical nanopore is also investigated and the corresponding results reveal that the GOM/conical nanopore system can perform the ion rectification behavior in a wider pH range than pure PET conical nanopore. The presented findings demonstrate the great potential applications of GOM/conical nanopore system in ionic logic circuits and sensor systems.

Preparation of Ag@zeolitic imidazolate framework-67 at room temperature for electrochemical sensing of hydrogen peroxide.

In this work, a novel non-enzymatic hydrogen peroxide sensor, Ag@zeolitic imidazolate framework-67 (Ag@ZIF-67)/glassy carbon electrode (GCE), was fabricated by a simple method at room temperature. The morphology and structure of Ag@ZIF-67 were investigated by scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, Fourier transform infrared spectroscopy, powder X-ray diffraction, atomic absorption spectrophotometry, and N2 absorption isotherms, which indicated that core-shell Ag@ZIF-67 was successfully synthesized with a porous rhombic dodecahedron structure. Electrochemical investigations demonstrated that the Ag@ZIF-67/GCE had strong electrocatalytic activity towards hydrogen peroxide reduction with a low detection limit of 1.5 µM (S/N = 3), a fast response time of 3 s, and three different linear relationships in the ranges of 5.0 µM-275 µM, 775 µM-2775 µM, and 4775 µM-16 775 µM with sensitivities of 27 µA mM-1 cm-2, 13 µA mM-1 cm-2, and 5.3 µA mM-1 cm-2, respectively. Moreover, the fabricated sensor exhibited an excellent recovery rate in real sample analysis of medical hydrogen peroxide disinfectant. These results proved that Ag@ZIF-67/GCE is an effective electrochemical sensor for detecting hydrogen peroxide.

Combined effect of cellulose nanocrystals and poly(butylene succinate) on poly(lactic acid) crystallization: The role of interfacial affinity.

Poly (lactic acid) (PLA)/cellulose nanocrystals (CNC), poly(butylene succinate) (PBS)/CNC and PLA/PBS/CNC composite films were prepared using a solution-casting technique. CNCs can be used to enhance the crystallization of PLA by offering more nucleation sites, and PBS can increase spherulite growth rate of PLA by providing flexible chains. However, CNCs and PBS together tend to interfere with each other and thus enhancement in the crystallization of PLA is lost. FTIR, contact-angle measurements, and dissolution experiments were used to characterize the materials. It was found that the interfacial affinity was greater in the CNC-PBS system than the CNC-PLA system. It was therefore concluded that the PBS chains occupy most of the CNC surfaces in the molten state before cooling. Consequently, PLA was mainly blocked from the CNCs and the nucleation effect was greatly weakened. The binary and ternary composite systems are discussed in terms of their crystallization processes.

Biozeolite capping for reducing nitrogen load of the ancient canal in Yangzhou City.

Biozeolite capping for reducing nitrogen (N) load of an eutrophic canal in Yangzhou City was studied. Biofilm formation on biozeolite was cultivated by use of isolated nitrifiers and denitrifiers. Varying conditions including dissolved oxygen (DO) and origins of isolated bacteria were considered in our experiments. Long-term sediment incubation experiment results showed that the reduction efficiency of total nitrogen (TN) of overlying water by biozeolite capping were in the range of 47.61-57.64% under the condition of DO<1 mg L(-1). There was no obvious difference in TN reduction efficiency between natural biozeolite (indigenous bacteria) and artificial biozeolite (isolated bacteria). However, the reduction efficiency of TN and nitrate nitrogen (NO(3)(-)-N) were respectively in the ranges of 67.38-76.12% and 69.38-76.12% under the condition of DO 1.5-5 mg L(-1). The reduction efficiencies of TN and NO(3)(-)-N by artificial biozeolite were improved by 25.99-27.25% and 17.50-24.15% respectively than those by natural biozeolite. Moreover, no significant difference was found for reducing N load by the isolated bacteria with different origins. TN contents of surface sediments and ammonia nitrogen concentrations of sediment interstitial water in biozeolite capping systems declined obviously after experiments. Biozeolite capping is an effective technique for reducing N load of the Yangzhou canal.

Asparagine 175 of connexin32 is a critical residue for docking and forming functional heterotypic gap junction channels with connexin26.

The gap junction channel is formed by proper docking of two hemichannels. Depending on the connexin(s) in the hemichannels, homotypic and heterotypic gap junction channels can be formed. Previous studies suggest that the extracellular loop 2 (E2) is an important molecular domain for heterotypic compatibility. Based on the crystal structure of the Cx26 gap junction channel and homology models of heterotypic channels, we analyzed docking selectivity for several hemichannel pairs and found that the hydrogen bonds between E2 domains are conserved in a group of heterotypically compatible hemichannels, including Cx26 and Cx32 hemichannels. According to our model analysis, Cx32N175Y mutant destroys three hydrogen bonds in the E2-E2 interactions due to steric hindrance at the heterotypic docking interface, which makes it unlikely to dock with the Cx26 hemichannel properly. Our experimental data showed that Cx26-red fluorescent protein (RFP) and Cx32-GFP were able to traffic to cell-cell interfaces forming gap junction plaques and functional channels in transfected HeLa/N2A cells. However, Cx32N175Y-GFP exhibited mostly intracellular distribution and was occasionally observed in cell-cell junctions. Double patch clamp analysis demonstrated that Cx32N175Y did not form functional homotypic channels, and dye uptake assay indicated that Cx32N175Y could form hemichannels on the cell surface similar to wild-type Cx32. When Cx32N175Y-GFP- and Cx26-RFP-transfected cells were co-cultured, no colocalization was found at the cell-cell junctions between Cx32N175Y-GFP- and Cx26-RFP-expressing cells; also, no functional Cx32N175Y-GFP/Cx26-RFP heterotypic channels were identified. Both our modeling and experimental data suggest that Asn(175) of Cx32 is a critical residue for heterotypic docking and functional gap junction channel formation between the Cx32 and Cx26 hemichannels.

[A indirect competitive ELISA to detect domoic acid in seawater and shellfish].

OBJECTIVE: A competitive enzyme-linked immunosorbent assay (ELISA) was developed for measurent domoic acid (DA) in seawater and shellfish. METHODS: DA was coupled to bovine serum albumin (BSA) and ovalbumin (OVA) by carbodiimide reaction. DA-BSA as immunogen was injected in BALB/c mice. Titres of the antisera against DA were determinated using DA-OVA as coating ligand by ELISA method. After female BALB/c mice were immunized six times, the polyclonal antibodies anti-DA was obtained. The competitive indirect ELISA for domoic acid in shellfish and seawater was established. RESULTS: Under optimal condition, the detection limit of DA was 10.0 ng/ml (equal 4 microg/g shellfish meat). The recovery of domoic acid added in seawater was 83.2% - 124.7% with a coefficient of variation of 4.7% - 5.9%, the recovery of domoic acid added in shellfish was 85.9% - 99.9% with a coefficient of variation of 2.4% - 7.1%.

[Effects of auricular acupuncture on the memory and the expression of ChAT and GFAP in model rats with Alzheimer's disease].

OBJECTIVE: To observe the effects of auricular acupuncture on the learning and memory abilities of model rats with Alzheimer's disease (AD), and investigate its mechanism. METHODS: Thirty SD rats were randomly divided into a control group, a model group and an auricular acupuncture group, 10 rats in each group. The model rats with AD were established by multiple injections with Okadaic Acid into the CA1 region of hippocampus. In the control group, the same quantity injection with Dimethyl Sulfoxide (DMSO) was applied on experimental rats. The auricular acupoints of "Nao" (brain) and "Shen" (kidney) were used for treating in the auricular acupuncture group, in contrast, the auricular region were not treated in the model and the control groups. The learning and memory capabilities of the rats were assessed with Morris Water Maze behavioral test, and the expressions of choline acetyltransferase (ChAT) and glial fibrillary acidic protein (GFAP) were examined by immunohistochemistry. RESULTS: Comparing with the model group, the treated AD rats with auricular acupuncture was showed that the average escape latency was obviously shortened in the place navigation test (P<0.01), the movement time in plateform quadrant was obviously prolonged in the spatial probe test (P<0.05), and the number of traversing platform obviously increased (P<0.01) after the platform was taken away. The expression of ChAT increased in the hippocampus and cortex (P<0.01, P<0.05), but the expression of GFAP obviously decreased in the CA1 region of hippocampus (P<0.01). CONCLUSION: Auricular acupuncture can improve the learning and memory capability of the model rats with AD. Its mechanism might be related with decreasing cholinergic neuron damage and reducing the abnormal activation and hyperplasia of astrocyte.