ABSTRACT
This study investigated the effects of combining Phragmites australis-based biochar, prepared at 400 °C, with various types of phosphate fertilizers-soluble, insoluble, and organic-on the content and transformation of phosphorus fractions in saline-alkali soil. Additionally, we explored microbiological mechanisms driving these transformations. The results showed that this combination significantly increased the concentrations of dicalcium phosphate (Ca2P), octacalcium phosphate (Ca8P), aluminum phosphate (AlP), moderately labile organic phosphorus (MLOP), and resistant organic phosphorus (MROP) in soil. Conversely, the levels of hydroxyapatite (Ca10P) and highly resistant organic phosphorus (HROP) decreased. The increase in labile organic phosphorus (LOP) content or decrease in iron phosphate (FeP) was found to effectively enhance the availability of Olsen phosphorus (Olsen-P) in soil. Furthermore, the study revealed that biochar mixed with organic phosphate fertilizers increased the activity of soil acid phosphatase (ACP) and neutral phosphatase (NEP), while reducing alkaline phosphatase (ALP) activity. In contrast, biochar combined with soluble and insoluble phosphate fertilizers decreased the activity of ACP (22.59 % and 28.57 %, respectively) and NEP (62.50 % and 11.11 %, respectively), with the combination with insoluble fertilizers also reducing ALP activity by 55.84 %, whereas the soluble combination increased it by 190.34 %. Additionally, the co-application of biochar and phosphate fertilizers altered the composition and abundance of the gene phoD-harboring microbial community, enhancing the abundance of Proteobacteria and reducing that of Actinobacteria. Correlation analysis between phoD-functional microbial species and various phosphorus fractions showed that Rhodopseudomonas was significantly associated with several phosphorus components, exhibiting a positive correlation with Ca2P, Ca8P, AlP, LOP, MLOP, and MROP, but a negative relationship with Ca10P. These findings suggest that the combined application of biochar and phosphate fertilizers could change the abundance of Rhodopseudomonas, potentially influencing phosphorus cycling in the soil. This research provides a strong scientific foundation for the efficient combined use of biochar and phosphate fertilizers in managing saline-alkali soil.
ABSTRACT
The glycoprotein GP64 of alphabaculovirus is crucial for viral entry and fusion. Here, we investigated the N-glycosylation patterns of Bombyx mori nucleopolyhedrovirus (BmNPV) GP64 and its signal peptide (SP) cleaved form, SPΔnGP64, along with their impacts on viral infectivity and fusogenicity. Through deglycosylation assays, we confirmed N-glycosylation of BmNPV GP64 on multiple sites. Mutational analysis targeting predicted N-glycosylation sites revealed diverse effects on viral infectivity and cell fusion. Particularly noteworthy were mutations at sites 175, which resulted in complete loss of infectivity and fusion capacity. Furthermore, LC-MS/MS analysis uncovered unexpected non-classical N-glycosylation sites, including N252, N302, N367, and N471, with only N302 and N471 identified in SPΔnGP64. Subsequent investigation highlighted the critical roles of these residues in BmNPV amplification and fusion, underscoring the essentiality of N367 glycosylation for GP64 fusogenicity. Our findings provide valuable insights into the non-classical glycosylation landscape of BmNPV GP64 and its functional significance in viral biology.
Subject(s)
Bombyx , Nucleopolyhedroviruses , Virus Internalization , Nucleopolyhedroviruses/genetics , Nucleopolyhedroviruses/metabolism , Nucleopolyhedroviruses/physiology , Glycosylation , Animals , Bombyx/virology , Bombyx/metabolism , Viral Envelope Proteins/metabolism , Viral Envelope Proteins/genetics , Glycoproteins/metabolism , Glycoproteins/genetics , Protein Sorting Signals , Tandem Mass Spectrometry , MutationABSTRACT
Baculovirus has been widely used for foreign protein expression in biomedical studies, and budded virus (BV) surface display has developed into an important research tool for heterogenous membrane protein studies. The basic strategy of surface display is to construct a recombinant virus where the target gene is fused with a complete or partial gp64 gene. In this study, we further investigate and develop this BV surface displaying strategy. We constructed stable insect cell lines to express the target protein flanking with different regions of signal peptide (SP) and GP64 transmembrane domain (TMD). Subsequently, recombinant BmNPV was used to infect the cell, and the integration of heterogeneous protein into BV was detected. The results indicated that deletion of the n-region of SP (SPΔn) decreased the incorporation rate more than that of the full-length SP. However, the incorporation rate of the protein fused with h and c-region deletion of SP (SPΔh-c) was significantly enhanced by 35-40 times compare to full-length SP. Moreover, the foreign protein without SP and TMD failed to display on the BV, while the integration of foreign proteins with GP64 TMD fusion at the c-terminal was significantly enhanced by 12-26 times compared to the control. Thus, these new strategies developed the BV surface display system further.
Subject(s)
Nucleopolyhedroviruses , Virion , Animals , Nucleopolyhedroviruses/genetics , Nucleopolyhedroviruses/metabolism , Cell Line , Virion/genetics , Virion/metabolism , Bombyx/virology , Viral Envelope Proteins/genetics , Viral Envelope Proteins/metabolism , Protein Sorting Signals/genetics , Protein Domains , Sf9 Cells , Virus AssemblyABSTRACT
Freestanding perovskite oxide membranes have drawn great attention recently since they offer exceptional structural tunability and stacking ability, providing new opportunities in fundamental research and potential device applications in silicon-based semiconductor technology. Among different types of sacrificial layers, the (Ca, Sr, Ba)3Al2O6 compounds are most widely used since they can be dissolved in water and prepare high-quality perovskite oxide membranes with clean and sharp surfaces and interfaces; However, the typical transfer process takes a long time (up to hours) in obtaining millimeter-size freestanding membranes, let alone realize wafer-scale samples with high yield. Here, a new member of the SrO-Al2O3 family, Sr4Al2O7 is introduced, and its high dissolution rate, ≈10 times higher than that of Sr3Al2O6 is demonstrated. The high-dissolution-rate of Sr4Al2O7 is most likely related to the more discrete Al-O networks and higher concentration of water-soluble Sr-O species in this compound. This work significantly facilitates the preparation of freestanding membranes and sheds light on the integration of multifunctional perovskite oxides in practical electronic devices.
ABSTRACT
Photoresponsivity is a fundamental parameter used to quantify the ability of photoelectric conversion of a photodetector device. High-responsivity photodetectors are essential for numerous optoelectronic applications. Due to the strong light-matter interactions and the high carrier mobility, two-dimensional (2D) materials are promising candidates for the next-generation photodetectors. However, poor light absorption, lack of photoconductive gain, and the interfacial recombination lead to the relatively low responsivity of 2D photodetectors. The photogating effect, which extends the lifetime of photoexcited carriers, provides a simple approach to enhance responsivity in photodetector devices. Here, the O2 plasma treatment introduced surface traps on the SnS2 surface, leading to a gate-tunable photogating effect in SnS2/MoS2 heterojunctions. The heterojunction device exhibits an ultrahigh responsibility of up to 28 A/W. Moreover, the photodetector possesses a wide spectral photoresponse spanning from 300 to 1100 nm and a high specific detectivity (D*) of 4 × 1011 Jones under a 532 nm laser at VDS = 1 V. These results demonstrate that O2 plasma treatment is an efficient and simple avenue to achieve photogating effects, which can be employed to enhance the performance of van der Waals heterostructure photodetector devices and make them suitable for future integration into advanced electronic and optoelectronic systems.
ABSTRACT
Circumventing the attenuation of microwaves during the propagation is of prime importance to wireless communication towards higher carrier frequencies. Here, we propose a scheme of wireless communications via a functionalized meta-window constructed by an optically-transparent metasurface (OTM) consisting of indium tin oxide (ITO) patterns. When the signal is weak, the OTM can significantly strengthen the signal by focusing the incoming waves towards the windowsill, thus substantially enhancing the network speed. The intensity enhancement of microwaves at 5â GHz via an OTM is verified by both numerical simulations and experiments. Furthermore, the ability to increase the data transfer rate in a 5-GHz-WiFi environment is directly demonstrated. Our work demonstrates the feasibility of applying an optically-transparent meta-window for enhancing wireless communications.
ABSTRACT
Controlling the dynamic processes, such as generation, separation, transport, and recombination, of photoexcited carriers in a semiconductor is foundational in the design of various devices for optoelectronic applications. One may imagine that if different processes can be manipulated in one single device and thus generate useful signals, a multifunctional device can be realized, and the toolbox for integrated optoelectronics will be expanded. Here, we revealed that in a graphene/ZnTe/graphene van der Waals (vdW) heterostructure, the carriers can be generated by illumination from visible to infrared frequencies, and thus, the detected spectrum range extends to the communication band, well beyond the band gap of ZnTe (2.26 eV). More importantly, we are able to control the competition between separation and recombination of the photoexcited carriers by an electric bias along the thickness-defined channel of the ZnTe flake: as the bias increases, the photodetecting performance, e.g. response speed and photocurrent, are improved due to the efficient separation of carriers; synchronously, the photoluminescence (PL) intensity decreases and even switches off due to the suppressed recombination process. The ZnTe-based vdW heterostructure device thus integrates both photodetection and PL switching functions by manipulating the generation, separation, transport, and recombination of carriers, which may inspire the design of the next generation of miniaturized optoelectronic devices based on the vdW heterostructures made by various thin flakes.
ABSTRACT
Acquiring homogeneous and reproducible wafer-scale transition metal dichalcogenide (TMDC) films is crucial for modern electronics. Metal-organic chemical vapor deposition (MOCVD) offers a promising approach for scalable production and large-area integration. However, during MOCVD synthesis, extraneous carbon incorporation due to organosulfur precursor pyrolysis is a persistent concern, and the role of unintentional carbon incorporation remains elusive. Here, we report the large-scale synthesis of molybdenum disulfide (MoS2) thin films, accompanied by the formation of amorphous carbon layers. Using Raman, photoluminescence (PL) spectroscopy, and transmission electron microscopy (TEM), we confirm how polycrystalline MoS2 combines with extraneous amorphous carbon layers. Furthermore, by fabricating field-effect transistors (FETs) using the carbon-incorporated MoS2 films, we find that traditional n-type MoS2 can transform into p-type semiconductors owing to the incorporation of carbon, a rare occurrence among TMDC materials. This unexpected behavior expands our understanding of TMDC properties and opens up new avenues for exploring novel device applications.
ABSTRACT
Two-dimensional electron gas (2DEG) at the interface of amorphous Al2O3/SrTiO3 (aAO/STO) heterostructures has received considerable attention owing to its convenience of fabrication and relatively high mobility. The integration of these 2DEG heterostructures on a silicon wafer is highly desired for electronic applications but remains challanging up to date. Here, conductive aAO/STO heterostructures have been synthesized on a silicon wafer via a growth-and-transfer method. A scanning transmission electron microscopy image shows flat and close contact between STO membranes and a Si wafer. Electron energy loss spectroscopic measurements reveal the interfacial Ti valence state evolution, which identifies the formation of 2D charge carriers confined at the interface of aAO/STO. This work provides a feasible strategy for the integration of 2DEG on a silicon wafer and other desired substrates for potential functional and flexible electronic devices.
ABSTRACT
Direct bandgap and significant anisotropic properties are crucial and beneficial for nanoelectronic applications. In this work, through first-principles calculations, we investigate novel two-dimensional (2D) α-XC (X = P, As, Sb, Bi) materials, which possess a direct bandgap of 0.73 to 1.40 eV with remarkable anisotropic electronic properties. Intriguingly, 2D α-XC presents the highest electron mobility near 8 × 103 cm2 V-1 s-1 along the Γ-X direction. Moreover, the transfer characteristics of the 2D α-XC TFETs are thoroughly assessed through NEGF methods. AsC TFETs demonstrate an on-state current larger than 2.2 × 103 µA µm-1, which can satisfy the International Technology Roadmap for Semiconductors (ITRS) for high-performance requirements. In particular, the minimum value of subthreshold swing of devices is as low as 15 mV dec-1, indicating excellent device switching characteristics. The relevant calculation results show that 2D α-XC monolayers could be a promising candidate in next-generation high-performance device applications.
ABSTRACT
Hexagonal boron nitride/graphene (hBN/G) vertical heterostructures have attracted extensive attention, owing to the unusual physical properties for basic research and electronic device applications. Here we report a facile deposition-segregation technique to synthesize hBN/G heterostructures on recyclable platinum (Pt) foil via low pressure chemical vapor deposition. The growth mechanism of the vertical hBN/G is demonstrated to be the surface deposition of hBN on top of the graphene segregated from the Pt foil with pre-dissolved carbon. The thickness of hBN and graphene can be controlled separately from sub-monolayer to multilayer through the fine control of the growth parameters. Further investigations by Raman, scanning Kelvin probe microscopy and transmission electron microscope show that the hBN/G inclines to form a heterostructure with strong interlayer coupling and with interlayer twist angle smaller than 1.5°. This deposition-segregation approach paves a new pathway for large-scale production of hBN/G heterostructures and could be applied to synthesize of other van der Waals heterostructures.
ABSTRACT
Ferroelectric domain wall memories have been proposed as a promising candidate for nonvolatile memories, given their intriguing advantages including low energy consumption and high-density integration. Perovskite oxides possess superior ferroelectric prosperities but perovskite-based domain wall memory integrated on silicon has rarely been reported due to the technical challenges in the sample preparation. Here, we demonstrate a domain wall memory prototype utilizing freestanding BaTiO3 membranes transferred onto silicon. While as-grown BaTiO3 films on (001) SrTiO3 substrate are purely c-axis polarized, we find they exhibit distinct in-plane multidomain structures after released from the substrate and integrated onto silicon due to the collective effects from depolarizing field and strain relaxation. Based on the strong in-plane ferroelectricity, conductive domain walls with reading currents up to nanoampere are observed and can be both created and erased artificially, highlighting the great potential of the integration of perovskite oxides with silicon for ferroelectric domain wall memories.
ABSTRACT
The real-time, in-line analysis of light polarization is critical in optical networks, currently suffering from complex systems with numerous bulky opto-electro-mechanical elements tandemly arranged along the optical path. Here, we design and fabricate a fiber-integrated polarimeter by vertically stacking three photodetection units based on six-layer van der Waals materials, including one bismuth selenide (Bi2Se3) layer for power calibration, two twisted black phosphorus (BP) layers for polarization detection, and three hexagonal boron nitride (hBN) layers for encapsulation. The self-power-calibrated, self-driven, and unambiguous detection of both linearly polarized (LP) and circularly polarized (CP) light is realized by the broken symmetry-induced linear photogalvanic effects (LPGEs) and circular photogalvanic effects (CPGEs) in the two BP units. Moreover, the device enables single-pixel polarimetric imaging to acquire spatial polarization information. The ultracompact device structure, free from external optical and mechanical modules, may inspire the development of miniaturized optical and optoelectronic systems.
ABSTRACT
Two-dimensional (2D) materials and their in-plane and out-of-plane (i.e., van der Waals, vdW) heterostructures are promising building blocks for next-generation electronic and optoelectronic devices. Since the performance of the devices is strongly dependent on the crystalline quality of the materials and the interface characteristics of the heterostructures, a fast and nondestructive method for distinguishing and characterizing various 2D building blocks is desirable to promote the device integrations. In this work, based on the color space information on 2D materials' optical microscopy images, an artificial neural network-based deep learning algorithm is developed and applied to identify eight kinds of 2D materials with accuracy well above 90% and a mean value of 96%. More importantly, this data-driven method enables two interesting functionalities: (1) resolving the interface distribution of chemical vapor deposition (CVD) grown in-plane and vdW heterostructures and (2) identifying defect concentrations of CVD-grown 2D semiconductors. The two functionalities can be utilized to quickly identify sample quality and optimize synthesis parameters in the future. Our work improves the characterization efficiency of atomically thin materials and is therefore valuable for their research and applications.
ABSTRACT
Corrosion of metals in atmospheric environments is a worldwide problem in industry and daily life. Traditional anticorrosion methods including sacrificial anodes or protective coatings have performance limitations. Here, we report atomically thin, polycrystalline few-layer graphene (FLG) grown by chemical vapor deposition as a long-term protective coating film for copper (Cu). A six-year old, FLG-protected Cu is visually shiny and detailed material characterizations capture no sign of oxidation. The success of the durable anticorrosion film depends on the misalignment of grain boundaries between adjacent graphene layers. Theoretical calculations further found that corrosive molecules always encounter extremely high energy barrier when diffusing through the FLG layers. Therefore, the FLG is able to prevent the corrosive molecules from reaching the underlying Cu surface. This work highlights the interesting structures of polycrystalline FLG and sheds insight into the atomically thin coatings for various applications.
ABSTRACT
Among large numbers of transition metal dichalcogenides (TMDCs), monolayer rhenium disulfide (ReS2) is of particular interest due to its unique structural anisotropy, which opens up unprecedented opportunities in dichroic atomical electronics. Understanding the domain structure and controlling the anisotropic evolution of ReS2 during the growth is considered critical for increasing the domain size toward a large-scale growth of monolayer ReS2. Herein, by employing angle-resolved Raman spectroscopy, we reveal that the hexagonal ReS2 domain is constructed by six well-defined subdomains with each b-axis parallel to the diagonal of the hexagon. By further combining the first-principles calculations and the transmission electron microscopy (TEM) characterization, a dislocation-involved anisotropic evolution is proposed to explain the formation of the domain structures and understand the limitation of the domain size. Based on these findings, growth rates of different crystal planes are well controlled to enlarge the domain size, and moreover, single-crystal domains with a triangle shape are obtained. With the improved domain size, large-scale uniform, strictly monolayer ReS2 films are grown further. Scalable field-effect transistor (FET) arrays are constructed, which show good electrical performances comparable or even superior to that of the single domains reported at room temperature. This work not only sheds light on comprehending the novel growth mechanism of ReS2 but also offers a robust and controllable strategy for the synthesis of large-area and high-quality two-dimensional materials with low structural symmetry.
ABSTRACT
The spatially precise integration of arrays of micropatterned two-dimensional (2D) crystals onto three-dimensionally structured Si/SiO2 substrates represents an attractive, low-cost system-on-chip strategy toward the realization of extended functions in silicon microelectronics. However, the reliable integration of such atomically thin arrays on planar patterned surfaces has proven challenging due to their poor adhesion to underlying substrates, as ruled by weak van der Waals interactions. Here, we report on an integration method utilizing the flexibility of the atomically thin crystals and their physical subsidence in liquids, which enables the reliable fabrication of the micropatterned 2D materials/Si arrays. Our photodiode devices display peak sensitivity as high as 0.35 A/W and external quantum efficiency (EQE) of â¼90%. The nano-subsidence technique represents a viable path to on-chip integration of 2D crystals onto silicon for advanced microelectronics.
ABSTRACT
Optical devices are highly attractive for biosensing as they can not only enable quantitative measurements of analytes but also provide information on molecular structures. Unfortunately, typical refractive index-based optical sensors do not have sufficient sensitivity to probe the binding of low-molecular-weight analytes. Non-optical devices such as field-effect transistors can be more sensitive but do not offer some of the significant features of optical devices, particularly molecular fingerprinting. We present optical conductivity-based mid-infrared (mid-IR) biosensors that allow for sensitive and quantitative measurements of low-molecular-weight analytes as well as the enhancement of spectral fingerprints. The sensors employ a hybrid metasurface consisting of monolayer graphene and metallic nano-antennas and combine individual advantages of plasmonic, electronic and spectroscopic approaches. First, the hybrid metasurface sensors can optically detect target molecule-induced carrier doping to graphene, allowing highly sensitive detection of low-molecular-weight analytes despite their small sizes. Second, the resonance shifts caused by changes in graphene optical conductivity is a well-defined function of graphene carrier density, thereby allowing for quantification of the binding of molecules. Third, the sensor performance is highly stable and consistent thanks to its insensitivity to graphene carrier mobility degradation. Finally, the sensors can also act as substrates for surface-enhanced infrared spectroscopy. We demonstrated the measurement of monolayers of sub-nanometer-sized molecules or particles and affinity binding-based quantitative detection of glucose down to 200 pM (36 pg/mL). We also demonstrated enhanced fingerprinting of minute quantities of glucose and polymer molecules.
ABSTRACT
Mass production of large, high-quality single-crystalline graphene is dependent on a complex coupling of factors including substrate material, temperature, pressure, gas flow, and the concentration of carbon and hydrogen species. Recent studies have shown that the oxidation of the substrate surface such as Cu before the introduction of the C precursor, methane, results in a significant increase in the growth rate of graphene while the number of nuclei on the surface of the Cu substrate decreases. We report on a phase-field model, where we include the effects of oxygen on the number of nuclei, the energetics at the growth front, and the graphene island morphology on Cu. Our calculations reproduce the experimental observations, thus validating the proposed model. Finally, and more importantly, we present growth rate from our model as a function of O concentration and precursor flux to guide the efficient growth of large single-crystal graphene of high quality.
ABSTRACT
Two-dimensional transition-metal dichalcogenides (TMDs) are unique candidates for the development of next-generation electronic devices. However, the large contact resistance between metal and the monolayer TMDs have significantly limited the devices' performance. Also, the integration of ultrathin high- k dielectric layers with TMDs remains difficult due to the lack of dangling bonds on the surface of TMDs. We present monolayer molybdenum disulfide field-effect transistors with bottom local gates consisting of monolayer graphene. The atomic-level thickness and surface roughness of graphene facilitate the growth of high-quality ultrathin HfO2 and suppress gate leakage. Strong displacement fields above 8 V/nm can be applied using a single graphene gate to electrostatically dope the MoS2, which reduces the contact resistances between Ni and monolayer MoS2 to 2.3 kΩ·µm at low gate voltages. The devices exhibit excellent switching characteristics including a near-ideal subthreshold slope of 64 millivolts per decade, low threshold voltage (â¼0.5 V), high channel conductance (>100 µS/µm), and low hysteresis. Scaled devices with 50 and 14 nm channels as well as ultrathin (5 nm) gate dielectrics show effective immunity to short-channel effects. The device fabricated on flexible polymeric substrate also exhibits high performance and has a fully transparent channel region that is desirable in optical-related studies and practical applications.