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Highlights: Gas-phase functionalization of X-MXene (X = –F, –OH, –O, –Br, –I) films crafted from sub-100 nm thin MXene flakes for highly sensitive NO2 sensors. I-MXene-based senor exhibited significant sensing performances toward trace NO2 at room temperature. The hydrophobicity, larger atomic size, lower electronegativity, and reduced shielding of -I contribute to the excellent sensing enhancement of I-MXene. In this study, precise control over the thickness and termination of Ti3C2TX MXene flakes is achieved to enhance their electrical properties, environmental stability, and gas-sensing performance. Utilizing a hybrid method involving high-pressure processing, stirring, and immiscible solutions, sub-100 nm MXene flake thickness is achieved within the MXene film on the Si-wafer. Functionalization control is achieved by defunctionalizing MXene at 650 °C under vacuum and H2 gas in a CVD furnace, followed by refunctionalization with iodine and bromine vaporization from a bubbler attached to the CVD. Notably, the introduction of iodine, which has a larger atomic size, lower electronegativity, reduce shielding effect, and lower hydrophilicity (contact angle: 99°), profoundly affecting MXene. It improves the surface area (36.2 cm2 g−1), oxidation stability in aqueous/ambient environments (21 days/80 days), and film conductivity (749 S m−1). Additionally, it significantly enhances the gas-sensing performance, including the sensitivity (0.1119 Ω ppm−1), response (0.2% and 23% to 50 ppb and 200 ppm NO2), and response/recovery times (90/100 s). The reduced shielding effect of the –I-terminals and the metallic characteristics of MXene enhance the selectivity of I-MXene toward NO2. This approach paves the way for the development of stable and high-performance gas-sensing two-dimensional materials with promising prospects for future studies. [ABSTRACT FROM AUTHOR]

3D straw-sheaf–like cobalt oxide (SS-Co3O4) was prepared via the hydrothermal method and inert gas calcination of precursors without the assistance of any template or surfactant. It was composed of numerous nanoneedles with a length of ~ 8 µm and a diameter of ~ 30 nm strongly tied in the center. The SS-Co3O4 exhibited high crystallinity, a large surface area (39.01 m2.g−1), a smaller pore size (6 nm), and lower charge transfer resistance (Rct = 9.35 Ω) at the electrode/electrolyte interface. A non-enzymatic glucose oxidizing electrode fabricated with SS-Co3O4 showed a high sensitivity (669 µA.mM−1.cm−2), wide linear range (0.04–4.85 mM), low limit of detection (0.31 µM), good selectivity, fast response time (5 s), and high reproducibility with a relative standard deviation of 2.25%. In addition, its robust structure demonstrated excellent electrochemical stability by retaining 83.8% of the initial sensitivity when its current density vs. time response was measured for 75 min in bare electrolytes prior to the glucose-sensing test. Furthermore, it demonstrated excellent repeatability performance by retaining 87.0% of the initial sensitivity when a single electrode was tested for 4 cycles. The proposed robust structured 3D SS-Co3O4 electrode successfully responds to the content of glucose in human saliva, which substantially proves its suitability in practical application. The synthesis technique is advantageous to prepare other metal oxides with interesting morphology and robust structure for the development of more reliable non-enzymatic glucometers and other electrochemical devices. [ABSTRACT FROM AUTHOR]

Summary: The bacterial communities in the wound tissues of Pinus massoniana were analysed by 16S rDNA amplicon sequencing. The results showed that the bacterial richness and diversity changed remarkably whether the wound was inoculated with pine wood nematode (PWN; Bursaphelenchus xylophilus) or not after 12 h. However, the predominant bacteria Stenotrophomonas , Burkholderiaceae, Pseudomonas , Serratia and Delftia , introduced by PWN in the wound tissues, changed within 6 h. After 6 h of PWN inoculation, the most abundant genus associating with PWN, Stenotrophomonas , failed to colonise the wound tissues, and the abundance of Delftia decreased, while the other representative bacteria, Burkholderiaceae, Pseudomonas and Serratia , from the PWN were markedly enriched. In addition, our study is the first to report the association of Serratia liquefaciens with PWN. Predicted functional analyses using the Tax4Fun tool showed that the alterations in bacterial composition also led to shifts in their functional pathways, especially after 12 h of PWN inoculation. These findings clarified that the bacteria carried by PWN were responsible for the alterations in bacterial communities in the wound tissues and will shed light on the invasion mechanism of PWN. [ABSTRACT FROM AUTHOR]

Large Schottky barrier at the electric contact interface drastically hinders the performance of two-dimensional (2D) semiconductor devices, because of which it is crucial to develop better methods to achieve the ohmic contact. Recently, a new field effect transistor (FET) device was constructed by the popular 2D channel material MoS2 and an electrode material borophene was detected theoretically, but the large Schottky barrier still existed. Hence, we used surface functional groups modification on the borophene surface to regulate this Schottky barrier, based on ab initio electronic structure calculations and quantum transport simulations. Our study shows that this method makes it possible to obtain tunable metal work functions in a wide range, and the ohmic contact can still be realized. Although van der Waals (vdW) contacts were observed at all the interfaces between the 2D borophene-based metals and the monolayer MoS2, the Fermi level pinning (FLP) effect was still obvious, and existed in our proposed system with the ohmic contact. Moreover, we also discuss the origin of the FLP with varying degrees. It was found that the interface dipole and metal-induced gap states (MIGS) would be responsible for the FLP of vertical and lateral directions, respectively. More precisely, we find that the size of MIGS is dependent on the relative orientation between the functional group and metal–MoS2 interface. This work not only suggests that surface functional group modification is effective in forming ohmic contact with MoS2, but also holds some implication in the fundamental research on metal–semiconductor contacts with the vdW type. [ABSTRACT FROM AUTHOR]

Pathogen infestation results in the change of the gene transcript level from the host plant, and part of these genes participate in the regulation of plant defense thereafter affects plant resistance. Infestation of Bursaphelenchus xylophilus on Pinus massoniana causes wilted leaves and, ultimately, the death of the plant. In order to reveal the underlying mechanism, the study here detected the dynamic expression of genes which involved in the signal transduction, defense, and cell metabolism in the P. massoniana. The results showed that gene expression was down-regulated in the P. massoniana with B. xylophilus infestation in comparison with the control group. These genes encode various proteins, which include calcium-binding protein, receptor-like protein kinase from signal transduction pathway; nicotianamine synthase, chitinase, and dehydration responsive protein that function in disease defense; DNA/RNA polymerases superfamily protein that involved in the DNA duplication, and cytochrome P450 mono-oxygenase superfamily and cytochrome P450 that related to cell detoxication. Our studies indicated that B. xylophilus infestation led to expression repression of the genes involved in the signal transduction and disease defense, which damages the systemic resistance on P. massoniana. [ABSTRACT FROM AUTHOR]

Tris(8-hydroxyquinoline) aluminum nanostructures are promising materials for nanooptoelectronic devices and molecular spintronics. In this paper, we report nanocrystals prepared by both physical vapor deposition (PVD) and facile solution method. The transmission electron microscopy (TEM) and high resolution scanning electron microscope (SEM) measurements show that the nanomaterials prepared by PVD technique are - nanoflowers, while the nanostructures prepared by solution method are - nanorods. Our experiments indicate that the - nanomaterials prepared by using solution method are more suitable for the fabrication of molecular spintronic devices than that of PVD method. [ABSTRACT FROM AUTHOR]

The magnetic properties of bis(8-hydroxyquinoline)copper () were investigated by experiments and first-principles density functional theory (DFT) calculations. The as-prepared film shows paramagnetic behavior. After annealing in air, room temperature ferromagnetic (FM) properties were found in film. The Fourier transform infrared spectroscopy (FTIR) analysis indicates a new vibrational mode related to out of plane O-H bend in the annealed film. DFT calculations show that the energy difference between the FM and the antiferromagnetic (AFM) states is greatly increased after O doping, which may be responsible for the room temperature ferromagnetism in the annealed film. [ABSTRACT FROM AUTHOR]