Ultra-Flexible, Breathable, and Robust PAN/MWCNTs/PANI Nanofiber Networks for High-Performance Wearable Gas Sensor Application.

Wearable gas sensors have drawn great attention for potential applications in health monitoring, minienvironment detection, and advanced soft electronic noses. However, it still remains a great challenge to simultaneously achieve excellent flexibility, high sensitivity, robustness, and gas permeability, because of the inherent limitation of widely used traditional organic flexible substrates. Herein, an electrospinning polyacrylonitrile (PAN) nanofiber network was designed as a flexible substrate, on which an ultraflexible wearable gas sensor was prepared with in situ assembled polyaniline (PANI) and multiwalled carbon nanotubes (MWCNTs) as a sensitive layer. The unique nanofiber network and strong binding force between substrate and sensing materials endow the wearable gas sensor with excellent robustness, flexibility, and gas permeability. The wearable sensor can maintain stable NH3 sensing performance while sustaining extreme bending and stretching (50% of strain). The Young's modulus of wearable PAN/MWCNTs/PANI sensor is as low as 18.9 MPa, which is several orders of magnitude smaller than those of reported flexible sensors. The water vapor transmission rate of the sensor is 0.38 g/(cm2 24 h), which enables the wearing comfort of the sensor. Most importantly, due to the effective exposure of sensing sites as well as the heterostructure effect between MWCNTs and PANI, the sensor shows high sensitivity to NH3 at room temperature, and the theoretical limit of detection is as low as 300 ppb. This work provides a new avenue for the realization of reliable and high-performance wearable gas sensors.

Transcription factor CgSte12 regulates pathogenicity by affecting appressorium structural development in the anthracnose-causing fungus Colletotrichum gloeosporioides.

Colletotrichum gloeosporioides is the causal agent of poplar anthracnose, which induces major economic losses and adversely affects the ecosystem services of poplar forests. The appressorium serves as a penetration structure for many pathogenic fungi, including C. gloeosporioides. The production of mucilage and the formation of penetration pegs are critically important for the appressorium-mediated penetration of host tissues. We previously found that CgPmk1 is a key protein involved in appressorium formation, penetration, and pathogenicity. Although CgSte12, which is a transcription factor that functions downstream of CgPmk1, regulates the formation of penetration pegs, its role in C. gloeosporioides appressorium development and pathogenicity has not been elucidated. Here, we developed C. gloeosporioides CgSTE12 mutants and characterized the molecular and cellular functions of CgSTE12. The results showed that mycelial growth and morphology were not affected in the CgSTE12 knockout mutants, which produced normal melanized appressoria. However, these mutants had less mucilage secreted around the appressoria, impaired appressorial cone formation, and the inability to form penetration pores and pegs, which ultimately led to a significant loss of pathogenicity. Our comparative transcriptome analysis revealed that CgSte12 controls the expression of genes involved in appressorium development and function, including genes encoding cutinases, NADPH oxidase, spermine biosynthesis-related proteins, ceramide biosynthesis-related proteins, fatty acid metabolism-related proteins, and glycerophospholipid metabolism-related proteins. Overall, our findings indicate that CgSte12 is a critical regulator of appressorium development and affects C. gloeosporioides pathogenicity by modulating the structural integrity of appressoria.

High-activity daisy-like zeolitic imidazolate framework-67/reduced grapheme oxide-based colorimetric biosensor for sensitive detection of hydrogen peroxide.

Colorimetric biosensors, based on enzyme-like nanomaterials, have come into the spotlight in virtue of their visual detection. Herein, a daisy-like zeolitic imidazolate framework-67/reduced grapheme oxide (ZIF-67/rGO) nanozyme with unique 3D hierarchical structures has been designed to realize visual detection of hydrogen peroxide (H2O2) that is recognized as a strong oxidizing agent or reactive oxygen species associated with oxidative stress in biological systems. The daisy-like ZIF-67/rGO is prepared by a facile one-step liquid-phase method conducted under room temperature. The successful introduction of rGO endows the daisy-like ZIF-67/rGO nanozyme with abundant porous structure, high specific surface area, and good charge transfer capability, which significantly accelerates the adsorbability and recognition towards the substrates and the oxidation rate of TMB-H2O2 reaction, and thus improving the nanozyme activity observably. It is conductive to nanozyme-modulated H2O2 determination. The established colorimetric biosensor platform based on ZIF-67/rGO nanozyme exhibits remarkable sensitivity and high specificity for the application in visual detection of H2O2. The detection limit of ZIF-67/rGO-based biosensor platform is as low as 3.81 µM, which is nearly 8 times lower than that of ZIF-67-based biosensor platform. Moreover, its potential applicability as an ideal platform for colorimetric biosensors is demonstrated by testing the concentration of H2O2 in milk samples, which sheds light on the promising application of the proposed biosensing system in point-of-care detection.

Analysis of melanin biosynthesis in the plant pathogenic fungus Colletotrichum gloeosporioides.

Melanin is recognized as a dark pigment that can protect fungi from the harm of environmental stresses. To investigate what roles of melanin played in the pathogenicity and development of Colletotrichum gloeosporioides, a causal agent of poplar anthracnose, genes encoding a transcription factor CgCmr1 and a polyketide synthase CgPks1 were isolated as the ortholog of Magnaporthe oryzae Pig1 and Pks1 respectively. Deletion of CgCmr1 or CgPks1 resulted in melanin-deficient fungal colony. The ΔCgPks1 mutant showed no melanin accumulation in appressoria, and lack of CgCmr1 also resulted in the delayed and decreased melanization of appressoria. In addition, the turgor pressure of the appressorium was lower in ΔCgPks1 and ΔCgCmr1 than in the wild-type (WT). However, DHN melanin was not a vital factor for virulence in C. gloeosporioides. Moreover, deletion of CgCmr1 and CgPks1 resulted in the hypersensitivity to hydrogen peroxide (H2O2) oxidative stress but not to other abiotic stresses. Collectively, these results suggest that CgCmr1 and CgPks1 play an important role in DHN melanin biosynthesis, and melanin was not an essential factor in penetration and pathogenicity in C. gloeosporioides. The data presented in this study will facilitate future evaluations of the melanin biosynthetic pathway and development in filamentous fungi.

Mucin Msb2 cooperates with the transmembrane protein Sho1 in various plant surface signal sensing and pathogenic processes in the poplar anthracnose fungus Colletotrichum gloeosporioides.

Colletotrichum gloeosporioides is a hemibiotrophic ascomycete fungus that causes anthracnose on numerous plants worldwide and forms a specialized infection structure known as an appressorium in response to various plant surface signals. However, the associated mechanism of host surface signal recognition remains unclear. In the present study, three putative sensors, namely the mucin Msb2, the membrane sensor protein Sho1, and the G-protein-coupled receptor Pth11, were identified and characterized. The results showed that CgMsb2 plays a major role in the recognition of various host surface signals; deletion of CgMsb2 resulted in significant defects in appressorium formation, appressorium penetration, cellophane membrane penetration, and pathogenicity. CgSho1 plays a minor role and together with CgMsb2 cooperatively regulates host signal recognition, cellophane membrane penetration, and pathogenicity; deletion of CgSho1 resulted in an expansion defect of infection hyphae. Deletion of CgPth11 in wildtype, ΔCgMsb2, and ΔCgSho1 strains only resulted in a slight defect in appressorium formation at the early stage, and CgPth11 was dispensable for penetration and pathogenicity. However, exogenous cAMP failed to restore the defect of appressorium formation in ΔCgPth11 at the early stage. CgMsb2 contributed to the phosphorylation of the mitogen-activated protein kinase CgMk1, which is essential for infection-associated functions, while CgSho1 was unable to activate CgMk1 alone but rather cooperated with CgMsb2 to activate CgMk1. These data suggest that CgMsb2 contributes to the activation of CgMk1 and has overlapping functions with CgSho1 in plant surface sensing, appressorium formation, and pathogenicity.

CgEnd3 Regulates Endocytosis, Appressorium Formation, and Virulence in the Poplar Anthracnose Fungus Colletotrichum gloeosporioides.

The hemibiotrophic ascomycete fungus Colletotrichum gloeosporioides is the causal agent of anthracnose on numerous plants, and it causes considerable economic losses worldwide. Endocytosis is an essential cellular process in eukaryotic cells, but its roles in C. gloeosporioides remain unknown. In our study, we identified an endocytosis-related protein, CgEnd3, and knocked it out via polyethylene glycol (PEG)-mediated protoplast transformation. The lack of CgEnd3 resulted in severe defects in endocytosis. C. gloeosporioides infects its host through a specialized structure called appressorium, and ΔCgEnd3 showed deficient appressorium formation, melanization, turgor pressure accumulation, penetration ability of appressorium, cellophane membrane penetration, and pathogenicity. CgEnd3 also affected oxidant adaptation and the expression of core effectors during the early stage of infection. CgEnd3 contains one EF hand domain and four calcium ion-binding sites, and it is involved in calcium signaling. A lack of CgEnd3 changed the responses to cell-wall integrity agents and fungicide fludioxonil. However, CgEnd3 regulated appressorium formation and endocytosis in a calcium signaling-independent manner. Taken together, these results demonstrate that CgEnd3 plays pleiotropic roles in endocytosis, calcium signaling, cell-wall integrity, appressorium formation, penetration, and pathogenicity in C. gloeosporioides, and it suggests that CgEnd3 or endocytosis-related genes function as promising antifungal targets.

Mitogen-activated protein kinase cascade CgSte50-Ste11-Ste7-Mk1 regulates infection-related morphogenesis in the poplar anthracnose fungus Colletotrichum gloeosporioides.

The hemibiotrophic pathogen Colletotrichum gloeosporioides is the causal agent of poplar anthracnose and causes considerable economic losses. This fungus infects its host through a specialized structure called an appressorium. In a previous study, we demonstrated that the mitogen-activated protein kinase (MAPK) CgMk1 plays a critical role in appressorium formation and pathogenicity. In this study, we identified three upstream components of CgMk1, the putative adaptor protein CgSte50, MAPKKK CgSte11, and MAPKK CgSte7, and showed that CgSte50, CgSte11, and CgSte7 positively regulate the phosphorylation of CgMk1. Deletion of CgSte50, CgSte11, and CgSte7 resulted in the loss of appressorium formation, penetration of the cellophane membrane, invasive growth and pathogenicity, similar to the defects observed in the CgMk1 mutant. CgSte50, CgSte11, CgSte7 and CgMk1 were also required for polarity during conidial germination. At the initial stage of appressorium formation, the accumulation of reactive oxygen species (ROS) was altered in the CgSte50, CgSte11, CgSte7 and CgMk1 deletion mutants compared with that in wild type (WT). Furthermore, the CgSte50, CgSte11, CgSte7 and CgMk1 deletion mutants manifested pleiotropic defects during vegetative growth; all mutants exhibited albino colonies, and the aerial hyphae had reduced hydrophobicity. In the mutants, autolysis was detected at the colony edge, and septum formation in the hyphae was elevated compared with that in the WT hyphae. Moreover, deletion of CgSte50, CgSte11, CgSte7 and CgMk1 affected vegetative growth under nitrogen-limiting and osmotic stress conditions. CgSte50, CgSte11, and CgSte7 but not CgMk1 were required for the oxidative stress response. Taken together, these results indicate that the CgMk1 MAPK cascade plays vital roles in various important functions in C. gloeosporioides.

High-Response, Ultrafast-Speed, and Self-Powered Photodetection Achieved in InP@ZnS-MoS2 Phototransistors with Interdigitated Pt Electrodes.

Various hybrid zero-dimensional/two-dimensional (0D/2D) systems have been developed to fabricate phototransistors with better performance compared to two-dimensional (2D) layered materials as well as broaden potential applications. Herein, we integrated environment-friendly InP@ZnS core-shell QDs with high efficiency of light absorption and light-emitting properties with bilayer MoS2 for the realization of 0D/2D mixed-dimensional phototransistors. Interdigitated (IDT) electrodes with Pt-patterned arrays, acting as light collectors as well as plasmonic resonators, can further enhance light harvesting from the InP@ZnS-MoS2 hybrid phototransistors, contributing to achieving a photoresponsivity as high as 1374 A·W-1. Moreover, thanks to the asymmetric Pt/MoS2 Schottky junction at the source/drain contact, a self-powered characteristic with an ultrafast speed of 21.5 µs was achieved, which is among the best performances for 2D layered material-based phototransistors. In terms of these features, we demonstrated the artificial synapse network with short-time plasticity based on the self-powered photodetection device. Our work reveals the great potential of 0D/2D hybrid phototransistors for high-response, ultrafast-speed, and self-powered photodetectors coupled with artificial neuromorphic function.

Enhanced photovoltaic properties of dye-sensitized solar cells using three-component CNF/TiO2/Au heterostructure.

To further increase the photoelectric efficiency of dye-sensitized solar cell (DSSC), enhancing the light adsorption of photoanode and suppressing the recombination of photo-generated charges are of great importance. Motivated by this, a novel and efficient three-component CNF/TiO2/Au heterostructure was successfully constructed and employed as an alternative photoanode material. The as-prepared CNF/TiO2/Au is characterized by conductive carbon nanofiber (CNF) core, uniform TiO2 outer shell assembled by upright nanorods, and surface modification with well-dispersed Au nanoparticles. To demonstrate the potential application of such material in DSSC, a comparison of photoelectric properties with commercial P25 and binary composite CNF/TiO2 was carried out. By contrast, the ternary composite CNF/TiO2/Au exhibited the highest short-circuit photocurrent density of 15.47 mA cm-2 and photoelectric conversion efficiency of 6.45%, which is about 31% higher than that of the commercial P25-based DSSCs. The great improvement of photoelectric properties for ternary composite CNF/TiO2/Au might be attributed to not only the conspicuous light adsorption ability derived from the sufficient dye loading of CNF/TiO2/Au and the surface plasmon resonance of Au nanoparticles, but also the reduced recombination endowed by the conductive CNF core and the heterojunctions at the interface.

Influence of interlayer interactions on the relaxation dynamics of excitons in ultrathin MoS2.

Interlayer interactions play a crucial role in modifying the optical and electronic properties of layered materials in a complex way, which is of key importance for the performance of the optoelectronic devices based on these novel materials. In this contribution, we performed an investigation into the underlying influence of interlayer interactions on the relaxation dynamics of excitons in ultrathin MoS2 using the femtosecond transient absorption spectroscopy technique. The experimental results manifest that interlayer interactions in bilayer MoS2 can largely facilitate the exciton-phonon scattering process and inhibit the radiative recombination process, which consequently accelerates the relaxation rate of A excitons and results in the decrease of the relaxation lifetime of A excitons in bilayer MoS2.

Octahedral-Like CuO/In2O3 Mesocages with Double-Shell Architectures: Rational Preparation and Application in Hydrogen Sulfide Detection.

This contribution describes a facile strategy for constructing octahedral-like CuO/In2O3 mesocages with double-shell architectures. The synthetic method included first preparation of unifrom Cu2O as an ideal self-sacrificial template and then decoration by a In2O3 outer layer through room-temperature Cu2O-engaged redox etching reaction combined with subsequent annealing process. Various characterization techniques manifested that In2O3 nanoparticles were uniformly grown on the surface of CuO mesocages, resulting in a well-defined double-shelled heterostructure. When evaluated as a novel sensing material for hydrogen sulfide (H2S) detection, the resultant octahedral-like CuO/In2O3 heterostructures exhibited obviously enhanced sensing response, lower operating temperature as well as faster response/recover speed during the dynamic measurement compared to the pristine CuO particles, which is likely related to the high-level of adsorbed oxygen concentration, resistance modulation effect, and unique microstructure of as-prepared CuO/In2O3 heterostructure.

[Comparison of manual versus automatic titration in pressure determination for long-term therapy of continuous positive airway pressure in patients with obstructive sleep apnea hypopnea syndrome].

OBJECTIVE: To compare the continuous positive airway pressure (CPAP) of automatic titration with that of manual titration. METHODS: A total of 58 patients with obstructive sleep apnea and hypopnea syndrome (OSAHS) diagnosed by overnight polysomnography at sleep center of First Affiliated Hospital, Guangzhou Medical University were studied between December 2010 and December 2012. Manual titration was performed under full polysmnography and auto-titration at home for 3-7 nights. RESULTS: There were 52 males and 6 females with an age range of (48 ± 11) years. CPAP pressure titrated by automatic device (10.0 ± 2.2) cm H2O (1 cm H2O = 0.098 kPa) was significantly higher than that titrated manually (7.5 ± 1.5) cm H2O (P = 0.000). Apnea-hyponea index decreased significantly from (54.0 ± 21.0) events/h pre-treatment to (3.8 ± 2.5) events/h post-treatment under manual titration (P < 0.01). CONCLUSIONS: CPAP pressure titrated by automatic device is usually higher than that titrated manually. Manual titration should be performed if a patient can not tolerate the CPAP pressure titrated by an automatic device.

[Prevalence of central sleep apnea in different age groups of children with sleep apnea-hypopnea].

OBJECTIVE: To explore the prevalence of central sleep apnea in different age groups of children with sleep apnea-hypopnea (SAH). METHODS: A total of 431 children with SAH diagnosed by overnight polysomnography at our Sleep Center were retrospectively studied. They were divided into 3 groups based on their ages: toddler group (1 - < 3 years old), preschool group (3 - < 6 years old) and school group (6 - < 13 years old). The relationship between age and different types of apnea-hyponea index (AHI) was analyzed. And the prevalence of central sleep apnea and sleep structure were compared between the groups. RESULTS: A negative correlation existed between age and central sleep apnea index (r = -0.322, P < 0.01). However, there was no correlation between age and obstructive apnea index (P > 0.05). AHI was similar in different age groups, but the medians of central sleep apnea index for toddler, preschool and school groups were 2.35, 1.50 and 0.90 events/h respectively (all P < 0.01). Sleep structure was similar between the groups (P > 0.05). CONCLUSIONS: Central sleep apnea is common in children with sleep disordered breathing. The younger their ages, a higher prevalence of central sleep apnea.

"Overpass" at the junction of a crossed microchannel: an enabler for 3D microfluidic chips.

Reported here is the design and fabrication of three-dimensional (3D) "overpass" microstructures at the junction of crossed microfluidic channels by femtosecond laser direct writing of photopolymers. The post-integrated overpass could be used for guiding different microfluids across the junction without mixing; therefore it is proposed as an enabler for achieving 3D microfluidic chips based on conventional two-dimensional (2D) microchannels. As representative examples, bi-crossed and tri-crossed microchannels have been equipped with bi-connected and tri-connected overpasses, respectively. Flow tests confirm 3D flowing capability. The integration of such overpass structures at the microchannel junction provides an opportunity to impart 3D capability to conventional 2D microchips, thus the method may hold great promise for both functionalization and miniaturization of Lab-on-a-Chip systems.