Genome-wide profiles of H3K9me3, H3K27me3 modifications, and DNA methylation during diapause of Asian corn borer (Ostrinia furnacalis).

Diapause represents a crucial adaptive strategy used by insects to cope with changing environmental conditions. In North China, the Asian corn borer (Ostrinia furnacalis) enters a winter larval diapause stage. Although there is growing evidence implicating epigenetic mechanisms in diapause regulation, it remains unclear whether dynamic genome-wide profiles of epigenetic modifications exist during this process. By investigating multiple histone modifications, we have discovered the essential roles of H3K9me3 and H3K27me3 during diapause of the Asian corn borer. Building upon previous findings in vertebrates highlighting the connection between DNA methylation and repressive histone methylations, we have examined changes in the genome-wide profile of H3K9me3, H3K27me3, and DNA methylation at the nondiapause, prediapause, and diapause stages. Data analysis reveals significant alterations in these three modifications during diapause. Moreover, we observe a correlation between the H3K9me3 and H3K27me3 modification sites during diapause, whereas DNA modifications show little association with either H3K9me3 or H3K27me3. Integrative analysis of epigenome and expression data unveils the relationship between these epigenetic modifications and gene expression levels at corresponding diapause stages. Furthermore, by studying the function of histone modifications on genes known to be important in diapause, especially those involved in the juvenile pathway, we discover that the juvenile hormone pathway lies downstream from H3K9me3 and H3K27me3 histone modifications. Finally, the analysis of gene loci with modified modifications unreported in diapause uncovers novel pathways potentially crucial in diapause regulation. This study provides a valuable resource for future investigations aiming to elucidate the underlying mechanisms of diapause.

Direct growth of single-chiral-angle tungsten disulfide nanotubes using gold nanoparticle catalysts.

Transition metal dichalcogenide (TMD) nanotubes offer a unique platform to explore the properties of TMD materials at the one-dimensional limit. Despite considerable efforts thus far, the direct growth of TMD nanotubes with controllable chirality remains challenging. Here we demonstrate the direct and facile growth of high-quality WS2 and WSe2 nanotubes on Si substrates using catalytic chemical vapour deposition with Au nanoparticles. The Au nanoparticles provide unique accommodation sites for the nucleation of WS2 or WSe2 shells on their surfaces and seed the subsequent growth of nanotubes. We find that the growth mode of nanotubes is sensitive to the temperature. With careful temperature control, we realize ~79% WS2 nanotubes with single chiral angles, with a preference of 30° (~37%) and 0° (~12%). Moreover, we demonstrate how the geometric, electronic and optical properties of the synthesized WS2 nanotubes can be modulated by the chirality. We anticipate that this approach using Au nanoparticles as catalysts will facilitate the growth of TMD nanotubes with controllable chirality and promote the study of their interesting properties and applications.

Intestinal perfusion of unacylated ghrelin alleviated metabolically associated fatty liver disease in rats via a central glucagon-like peptide-1 pathway.

Unacylated ghrelin (UAG), the unacylated form of ghrelin, accounts for 80%-90% of its circulation. Accumulated studies have pointed out that UAG may be used to treat metabolic disorders. This study aimed to investigate the effect of intestinal perfusion of UAG on metabolically associated fatty liver disease (MAFLD) induced by a high-fat diet and its possible mechanisms. Neuronal retrograde tracking combined with immunofluorescence, central administration of a glucagon-like peptide-1 receptor (GLP-1R) antagonist, and hepatic vagotomy was performed to reveal its possible mechanism involving a central glucagon-like peptide-1 (GLP-1) pathway. The results showed that intestinal perfusion of UAG significantly reduced serum lipids, aminotransferases, and food intake in MAFLD rats. Steatosis and lipid accumulation in the liver were significantly alleviated, and lipid metabolism-related enzymes in the liver were regulated. UAG upregulated the expression of GLP-1 receptor (GLP-1R) in the paraventricular nucleus (PVN) and GLP-1 in the nucleus tractus solitarii (NTS), as well as activated GLP-1 neurons in the NTS. Furthermore, GLP-1 fibers projected from NTS to PVN were activated by the intestinal perfusion of UAG. However, hepatic vagotomy and GLP-1R antagonists delivered into PVN before intestinal perfusion of UAG partially attenuated its alleviation of MAFLD. In conclusion, intestinal perfusion of UAG showed a therapeutic effect on MAFLD, which might be related to its activation of the GLP-1 neuronal pathway from NTS to PVN. The present results provide a new strategy for the treatment of MAFLD.NEW & NOTEWORTHY Intestinal perfusion of UAG, the unacylated form of ghrelin, has shown promising potential for treating MAFLD. This study unveils a potential mechanism involving the central GLP-1 pathway, with UAG upregulating GLP-1R expression and activating GLP-1 neurons in specific brain regions. These findings propose a novel therapeutic strategy for MAFLD treatment through UAG and its modulation of the GLP-1 neuronal pathway.

An Integrated Navigation Method Aided by Position Correction Model and Velocity Model for AUVs.

When autonomous underwater vehicles (AUVs) perform underwater tasks, the absence of GPS position assistance can lead to a decrease in the accuracy of traditional navigation systems, such as the extended Kalman filter (EKF), due to the accumulation of errors. To enhance the navigation accuracy of AUVs in the absence of position assistance, this paper proposes an innovative navigation method that integrates a position correction model and a velocity model. Specifically, a velocity model is developed using a dynamic model and the Optimal Pruning Extreme Learning Machine (OP-ELM) method. This velocity model is trained online to provide velocity outputs during the intervals when the Doppler Velocity Log (DVL) is not updating, ensuring more consistent and reliable velocity estimation. Additionally, a position correction model (PCM) is constructed, based on a hybrid gated recurrent neural network (HGRNN). This model is specifically designed to correct the AUV's navigation position when GPS data are unavailable underwater. The HGRNN utilizes historical navigation data and patterns learned during training to predict and adjust the AUV's estimated position, thereby reducing the drift caused by the lack of real-time position updates. Experimental results demonstrate that the proposed VM-PCM-EKF algorithm can significantly improve the positioning accuracy of the navigation system, with a maximum accuracy improvement of 87.2% compared to conventional EKF algorithms. This method not only improves the reliability and accuracy of AUV missions but also opens up new possibilities for more complex and extended underwater operations.

Pressure-Modulated Interface Engineering toward Realizing Core@Shell Configuration Transition.

The strained interface of core@shell nanocrystals (NCs) can effectively modulate the energy level alignment, thereby significantly affecting the optical properties. Herein, the unique photoluminescence (PL) response of doped Mn ions is introduced as a robust probe to detect the targeted pressure-strain relation of CdS@ZnS NCs. Results show that the core experiences actually less pressure than the applied external pressure, attributed to the pressure-induced optimized interface that reduces the compressive strain on core. The pressure difference between core and shell increases the conduction band and valence band offsets and further achieves the core@shell configuration transition from quasi type II to type I. Accordingly, the PL intensity of CdS@ZnS NCs slightly increases, along with a faster blue-shift rate of PL peak under low pressure. This study elucidates the interplay between external physical pressure and interfacial chemical stress for core@shell NCs, leading to precise construction of interface engineering for practical applications.

Dynamic Pluronic F127 Crosslinking Enhancement of Biopolymeric Nanocomposites for Piezo-Triboelectric Single-Hybrid Nanogenerators and Self-Powered Sensors.

Biomechanical and nanomechanical energy harvesting systems have gained a wealth of interest, resulting in a plethora of research into the development of biopolymeric-based devices as sustainable alternatives. Piezoelectric, triboelectric, and hybrid nanogenerator devices for electrical applications are engineered and fabricated using innovative, sustainable, facile-approach flexible composite films with high performance based on bacterial cellulose and BaTiO3 , intrinsically and structurally enhanced by Pluronic F127, a micellar cross-linker. The voltage and current outputs of the modified versions with multiwalled carbon nanotube as a conductivity enhancer and post-poling effect are 38 V and 2.8 µA cm-2 , respectively. The multiconnective devices' power density can approach 10 µW cm-2 . The rectified output power is capable of charging capacitors, driving light-emitting diode lights, powering a digital watch and interfacing with a commercial microcontroller board to operate as a piezoresistive force sensor switch as a proof of concept. Magnetoelectric studies show that the composites have the potential to be incorporated into magnetoelectric systems. The biopolymeric composites prove to be desirable candidates for multifunctional energy harvesters and electronic devices.

Scalable Bacterial Cellulose-Based Radiative Cooling Materials with Switchable Transparency for Thermal Management and Enhanced Solar Energy Harvesting.

Radiative cooling materials that can dynamically control solar transmittance and emit thermal radiation into cold outer space are critical for smart thermal management and sustainable energy-efficient buildings. This work reports the judicious design and scalable fabrication of biosynthetic bacterial cellulose (BC)-based radiative cooling (Bio-RC) materials with switchable solar transmittance, which are developed by entangling silica microspheres with continuously secreted cellulose nanofibers during in situ cultivation. Theresulting film shows a high solar reflection (95.3%) that can be facilely switched between an opaque state and a transparent state upon wetting. Interestingly, the Bio-RC film exhibits a high mid-infrared emissivity (93.4%) and an average sub-ambient temperature drop of ≈3.7 °C at noon. When integrating with a commercially available semi-transparent solar cell, the switchable solar transmittance of Bio-RC film enables an enhancement of solar power conversion efficiency (opaque state: 0.92%, transparent state: 0.57%, bare solar cell: 0.33%). As a proof-of-concept illustration, an energy-efficient model house with its roof built with Bio-RC-integrated semi-transparent solar cell is demonstrated. This research can shine new light on the design and emerging applications of advanced radiative cooling materials.

Epigenetic regulator Stuxnet modulates octopamine effect on sleep through a Stuxnet-Polycomb-Octß2R cascade.

Sleep homeostasis is crucial for sleep regulation. The role of epigenetic regulation in sleep homeostasis is unestablished. Previous studies showed that octopamine is important for sleep homeostasis. However, the regulatory mechanism of octopamine reception in sleep is unknown. In this study, we identify an epigenetic regulatory cascade (Stuxnet-Polycomb-Octß2R) that modulates the octopamine receptor in Drosophila. We demonstrate that stuxnet positively regulates Octß2R through repression of Polycomb in the ellipsoid body of the adult fly brain and that Octß2R is one of the major receptors mediating octopamine function in sleep homeostasis. In response to octopamine, Octß2R transcription is inhibited as a result of stuxnet downregulation. This feedback through the Stuxnet-Polycomb-Octß2R cascade is crucial for sleep homeostasis regulation. This study demonstrates a Stuxnet-Polycomb-Octß2R-mediated epigenetic regulatory mechanism for octopamine reception, thus providing an example of epigenetic regulation of sleep homeostasis.

Fine particles removal of pyrolysis gasification flue gas from rural domestic waste: Laboratory research, molecular dynamics simulation, and applications.

Chinese rural domestic waste has increased considerably with the modernization of agriculture and urbanization. Pyrolysis gasification is a common high-temperature waste treatment method. However, this method is usually accompanied by a large amount of particle emission. In this study, a rural domestic waste pyrolysis gasification station in Gansu Province, Northwest China, was selected for research. The particle emission characteristics of this station were analyzed, and the results showed that the original particle removal technologies were inefficient in fine particles. Hence, a new method of fine particle treatment, i.e., Cloud-Air-Purifying (CAP) technology, was explored herein. In CAP, fine particles grow in size via heterogeneous condensation in a supersaturated water vapor environment and are then collected efficiently using a supergravity field. A laboratory-scale pyrolysis gasifier and CAP equipment were built. Moreover, the CAP removal efficiency for particles generated from four typical rural domestic waste categories was studied. The results showed that CAP technology considerably increased the efficiency of fine particle removal. However, the removal efficiency for particles released owing to the incineration of wood was only ∼75%. This was because the tar substances formed during wood pyrolysis were attached to the surface of escaping particles, which led to a decrease in their hydrophilicity and particle condensation growth. To address this issue, the improvement in particle hydrophilicity using different surfactants was studied via molecular dynamic simulations. When the increase in water molecule adsorption, surface polarity, and the solid-liquid interaction energy for different surfactants were compared, alkylphenol ethoxylate (OP10) proved to be the most effective surfactant. Finally, the improved CAP technology combined with OP10 was applied to the on-site pyrolysis gasification flue gas treatment. Long term monitoring of the proposed technology revealed that particle removal efficiency remained >94%, exhibiting excellent fine particle removal. The successful application of the proposed technology demonstrates its potential for further application.

Fulvic acid enhanced peroxymonosulfate activation over Co-Fe binary metals for efficient degradation of emerging bisphenols.

Bisphenol F (BPF) and bisphenol S (BPS) are emerging bisphenols, which have become the main substitutes for bisphenol A (BPA) in industrial production and are also considered as new environmental pollution challenges. Thus, the necessity for an effective approach to remove BPF and BPS is essential. In this study, fulvic acid (FA) was used to modify Co-Fe binary metals (CFO) for peroxymonosulfate (PMS) activation. The characterization results demonstrated that CFO changed significantly in morphology after compounding with FA, with smaller particle size and 5.6 times larger specific surface area, greatly increasing the active sites of catalyst; Moreover, humic acid-like compounds increased the surface functional groups of CFO, especially phenolic hydroxyl, which could effectively prolong the PMS activation. The concentration of all reactive species, such as SO4•-, •OH, O2•-, and 1O2 increased in FA@CFO/PMS system. As a result, the degradation efficiency of CFO for both BPF and BPS was significantly improved after compounding FA, which also had a wide range of pH applications. The degradation pathways of both BPF and BPS were proposed based on liquid chromatography-mass spectrometry (LC-MS) analysis and the density functional theory (DFT) calculations. Our findings are expected to provide new strategies and methods for remediation of environmental pollution caused by emerging bisphenols.

Multi-Objective Association Detection of Farmland Obstacles Based on Information Fusion of Millimeter Wave Radar and Camera.

In order to remedy the defects of single sensor in robustness, accuracy, and redundancy of target detection, this paper proposed a method for detecting obstacles in farmland based on the information fusion of a millimeter wave (mmWave) radar and a camera. Combining the advantages of the mmWave radar in range and speed measurement and the camera in type identification and lateral localization, a decision-level fusion algorithm was designed for the mmWave radar and camera information, and the global nearest neighbor method was used for data association. Then, the effective target sequences of the mmWave radar and the camera with successful data association were weighted to output, and the output included more accurate target orientation, longitudinal speed, and category. For the unassociated sequences, they were tracked as new targets by using the extended Kalman filter algorithm and were processed and output during the effective life cycle. Lastly, an experimental platform based on a tractor was built to verify the effectiveness of the proposed association detection method. The obstacle detection test was conducted under the ROS environment after solving the external parameters of the mmWave radar and the internal and external parameters of the camera. The test results show that the correct detection rate of obstacles reaches 86.18%, which is higher than that of a single camera with 62.47%. Furthermore, through the contrast experiment of the sensor fusion algorithms, the detection accuracy of the decision level fusion algorithm was 95.19%, which was higher than 4.38% and 6.63% compared with feature level and data level fusion, respectively.

Luteolin alleviates non-alcoholic fatty liver disease in rats via restoration of intestinal mucosal barrier damage and microbiota imbalance involving in gut-liver axis.

Nonalcoholic fatty liver disease (NAFLD) is demonstrated to be closely related to the disorder of gut microbiota and the intestinal mucosal barrier. Luteolin is a natural flavonoid with various activities. We aimed to investigate whether Luteolin can alleviate NAFLD and its possible mechanism involving the gut-liver axis. A rat NAFLD model was established by feeding a high-fat diet (HFD), and Luteolin was administered intragastrically. The effects of Luteolin on liver biochemical parameters, intestinal histopathology and integrity, gut microbiota, lipopolysaccharides (LPS), inflammatory cytokines, and the Toll-like receptor 4 (TLR4) signaling pathway were evaluated. We found that Luteolin restored the expression of the tight junction proteins in the intestine and ameliorated the increase permeability of the intestinal mucosa to Fluorescein isothiocyanate-dextran (FD4) caused by a high-fat diet, thus enhancing the function of the intestinal barrier. In addition, Luteolin inhibited the TLR4 signaling pathway in the liver, thereby reducing the secretion of pro-inflammatory factors and alleviating NAFLD. 16S rRNA gene sequencing revealed that Luteolin intervention significantly altered the composition of the gut microbiota in NAFLD rats and increased the richness of gut microbiota. Luteolin alleviates NAFLD in rats via restoration and repair of the damaged intestinal mucosal barrier and microbiota imbalance.

Near-Infrared Light-Driven Shape-Morphing of Programmable Anisotropic Hydrogels Enabled by MXene Nanosheets.

Herein, we report near-infrared (NIR) light-driven shape-morphing of programmable MXene-containing anisotropic hydrogel actuators that are fabricated through in situ free-radical copolymerization of a judiciously designed MXene nanomonomer with thermosensitive hydrogel network. A low electric field (few V mm-1 ) was found to enable a spatial distribution of MXene nanosheets and hence introduce anisotropy into the hydrogel network. Programmable anisotropic hydrogel actuators were developed by controlling ITO electrode pattern, direct-current (DC) electric field direction and mask-assisted photopolymerization. As a proof-of-concept, we demonstrate NIR light-driven shape morphing of the MXene-containing anisotropic hydrogel into various shapes and devise a four-arm soft gripper that can perform distinct photomechanical functions such as grasping, lifting/lowering down and releasing an object upon sequential NIR light exposure.

Fabrication of Form-Stable Phase Change Materials Based on Mechanically Flexible SiO2 Nanofibrous Mats for Thermal Energy Storage/Retrieval.

For overcoming the fragility of inorganic supporting materials as form-stable phase change materials (FSPCMs), flexible and soft SiO2 nanofibrous mats were applied as supporting materials of FSPCMs for storage/retrieval of thermal energy. Quaternary fatty acid eutectics were incorporated into SiO2 nanofibrous mats as representative phase change materials. Flexible SiO2 nanofibrous mats were prepared by electrospinning combined with annealing. The thermal energy storage capability, surface morphology and thermal energy storage/retrieval rate of FSPCMs were characterized by differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and laboratorymade thermal performance measurement device. The results indicated that the resultant SiO2 nanofibrous mats were soft and free-standing. Quaternary fatty acid eutectics were distributed uniformly in the three-dimensional (3D) network structure of the SiO2 nanofibrous mats, thereby effectively preventing fatty acid leakage. The absorption capacities of five types of quaternary fatty acid eutectics varied from 85.1% to 88.9%. Moreover, after 20 cycles, the phase change temperature and enthalpy of FSPCMs did not change significantly, suggesting that ideal thermal stability was achieved. The time for thermal energy storage/retrieval taken by FSPCMs was shortened by 23.1% at minimum from that for pure quaternary fatty acid eutectics. Therefore, the fabricated FSPCMs offer promising application prospects in a wide variety of fields, including solar energy utilization, temperature-regulating textiles and air-conditioning systems.

Pressure-Induced Large Emission Enhancements of Cadmium Selenide Nanocrystals.

Pressure quenching of optical emission largely limits the potential application of many materials in optical pressure-sensing devices, since emission intensity is crucially connected to performance. Boosting visible-light emission at high pressure is, therefore, an important goal. Here, we demonstrate that the emission of CdSe nanocrystals (NCs) can be enhanced by more than an order of magnitude by compression. The brightest emission can be achieved at pressures corresponding to the phase transitions in different sized CdSe NCs. Very bright blue emission can be obtained by exploiting the increase in band gap with increasing pressure. First-principles calculations indicate that the interaction between the capping oleic acid (OA) layer and the CdSe core is strengthened with increased Hirshfeld charge at high pressure. The effective surface reconstruction associated with the removal of surface-related trap states is highly responsible for the pressure-induced emission enhancement of these CdSe NCs. These findings pave the way for designing a stress nanogauge with easy optical readout and provide a route for tuning bright-fluorescence imaging in response to an externally applied pressure.

Pt9 Ni Wavelike Nanowires with High Activity for Oxygen Reduction Reactions.

Platinum (Pt)-based nanostructures are the most efficient catalysts for the oxygen reduction reaction (ORR) in acid media. Here, Pt9 Ni wavelike nanowires (W-NWs) have been synthesized by etching Pt3 Ni@PtNi2 core-shell nanowires with 2,5-dihydroxyterephthalic acid for 24 hours. Compared to the commercial Pt/C catalyst, the free-standing Pt9 Ni W-NWs show improvements of up to 9.3 times for mass activity and 12.6 times for specific activity, respectively.

Research on the Temperature Characteristics of the Photoacoustic Sensor of Glucose Solution.

In order to weaken the influence of temperature on photoacoustic (PA) measurements and compensate PA signals with a proposed theoretical model, the relationship of PA signal amplitude with temperature, under the condition of different glucose concentrations and different light intensities, was studied in this paper. First, the theoretical model was derived from the theory of the PA effect. Then, the temperature characteristics of the PA signals were investigated, based on the analyses of the temperature-dependent Grüneisen parameter in glucose solution. Next, the concept of a PA temperature coefficient was proposed in this paper. The result of the theoretical analysis shows that this coefficient is linear to light intensity and irrelevant to the concentration of glucose solution. Furthermore, a new concept of a PA temperature coefficient of unit light intensity was proposed in this paper. This coefficient is approximately constant, with different light intensities and solution concentrations, which is similar to the thermal expansion coefficient. After calculation, the PA temperature coefficient by the unit light intensity of glucose solution is about 0.936 bar/K. Finally, relevant experiments were carried out to verify the theoretical analysis, and the PA temperature coefficient of the unit light intensity of glucose solution is about 0.04/°C. This method can also be used in sensors measuring concentrations in other aqueous solutions.

Klotho ameliorates cyclosporine A-induced nephropathy via PDLIM2/NF-kB p65 signaling pathway.

Klotho, an antiaging protein, can extend the lifespan and modulate cellular responses to inflammation and oxidative stress which can ameliorate chronic kidney diseases (CKD). To investigate the molecular mechanism of Klotho on inflammation in cyclosporine A (CsA) induced nephropathy, the mice were transfected with adenovirus mediated Klotho gene and treated with cyclosporine A (CsA; 30 mg/kg/day) for 4 weeks. Also, primary human renal proximal tubule epithelial cells (RPTECs) were treated with soluble Klotho protein and LPS. The results showed that Ad-klotho significantly reduced serum creatinine (Scr) and blood urea nitrogen (BUN) caused by CsA, and significantly increased creatinine clearance. Tubule interstitial fibrosis score (TIF), renal 8-OHdG excretion, macrophage infiltration and MCP-1 were decreased after Ad-klotho gene transfer. In addition, the overexpression of Klotho led to increase in the expression of PDLIM2, decreased in the amount of NF-kB p65, and inhibited the production of inflammatory cytokines (TNFα, IL-6, IL-12) and iNOS. Accordingly, in vitro results showed, Klotho enhanced PDLIM2 expression and reduced NF-kB p65 expression, while PDLIM2 siRNA could block the inhibitory effects of Klotho on expression of NF-kB p65. Secretion of inflammatory cytokines was also inhibited by Klotho treatment, and PDLIM2 siRNA hindered regulatory effects of Klotho on the cytokines. Real-time PCR and Luciferase assay showed that Klotho markedly increased expression of PDLIM2 mRNA and PDLIM2 reporter activity in a dose-dependent manner. These findings suggest that Klotho can modulate inflammation via PDLIM2/NF-kB p65 pathway in CsA-induced nephropathy.

In Situ Local Contact Angle Measurement in a CO2-Brine-Sand System Using Microfocused X-ray CT.

The wettability of porous media is of major interest in a broad range of natural and engineering applications. The wettability of a fluid on a solid surface is usually evaluated by the contact angle between them. While in situ local contact angle measurements are complicated by the topology of porous media, which can make it difficult to use traditional methods, recent advances in microfocused X-ray computed tomography (micro-CT) and image processing techniques have made it possible to measure contact angles on the scale of the pore sizes in such media. However, the effects of ionic strength, CO2 phase, and flow pattern (drainage or imbibition) on pore-scale contact angle distribution are still not clear and have not been reported in detail in previous studies. In this study, we employed a micro-CT scanner for in situ investigation of local contact angles in a CO2-brine-sand system under various conditions. The effects of ionic strength, CO2 phase, and flow pattern on the local contact-angle distribution were examined in detail. The results showed that the local contact angles vary over a wide range as a result of the interaction of surface contaminants, roughness, pore topology, and capillarity. The wettability of a porous surface could thus slowly weaken with increasing ionic strength, and the average contact angle could significantly increase when gaseous CO2 (gCO2) turns into supercritical CO2 (scCO2). Contact angle hysteresis also occurred between drainage and imbibition procedures, and the hysteresis was more significant under gCO2 condition.

Design of flexible PANI-coated CuO-TiO2-SiO2 heterostructure nanofibers with high ammonia sensing response values.

We report a room-temperature ammonia sensor with extra high response values and ideal flexibility, including polyaniline (PANI)-coated titanium dioxide-silicon dioxide (TiO2-SiO2) or copper oxide-titanium dioxide-silicon dioxide (CuO-TiO2-SiO2) composite nanofibers. Such flexible inorganic TiO2-SiO2 and CuO-TiO2-SiO2 composite nanofibers were prepared by electrospinning, followed by calcination. Then, in situ polymerization of aniline monomers was carried out with inorganic TiO2-SiO2 and CuO-TiO2-SiO2 composite nanofibers as templates. Gas sensing tests at room temperature indicated that the obtained CuO-TiO2-SiO2/PANI composite nanofibers had much higher response values to ammonia gas (ca. 45.67-100 ppm) than most of those reported before as well as the prepared TiO2-SiO2/PANI composite nanofibers here. These excellent sensing properties may be due to the P-N, P-P heterojunctions and a structure similar to field-effect transistors formed on the interfaces between PANI, TiO2, and CuO, which is p-type, n-type, and p-type semiconductor, respectively. In addition, the prepared free-standing CuO-TiO2-SiO2/PANI composite nanofiber membrane was easy to handle and possessed ideal flexibility, which is promising for potential applications in wearable sensors in the future.