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Liquid film cooling by jet–wall impingement on the combustor wall is commonly used in small rocket engines. The heat transfer mechanism inside the liquid film is closely related to the film flow. Therefore, we establish a comprehensive analytical model with reasonable assumptions for the liquid film flow by inclined jet–wall impingement, and we validate it through a series of experiments. It is found that the predicted liquid film dimensions agree well with the experimental results. As the impingement angle increases from 30 to 60 deg, the shape of the liquid film turns from an oval to a circle. With the increase of the impingement velocity from 7.8 to [Formula: see text], the width, length, and area of the liquid film increase. The wall roughness [Formula: see text] ranges from 6.3 to [Formula: see text], which shows negligible effects on the liquid film dimensions. As the surface tension increases from 36.03 to 67.13 mN/m and the viscosity increases from 1 to [Formula: see text], the dimensions of the liquid film decrease. The effect of viscosity is more significant than surface tension within the scope of this experiment. Finally, an empirical correlation for the three investigated film dimensional parameters is proposed.

Two-dimensional (2D) transition metal dichalcogenides (TMDs) with fascinating electronic energy band structures, rich valley physical properties and strong spin–orbit coupling have attracted tremendous interest, and show great potential in electronic, optoelectronic, spintronic and valleytronic fields. Stacking 2D TMDs have provided unprecedented opportunities for constructing artificial functional structures. Due to the low cost, high yield and industrial compatibility, chemical vapor deposition (CVD) is regarded as one of the most promising growth strategies to obtain high-quality and large-area 2D TMDs and heterostructures. Here, state-of-the-art strategies for preparing TMDs details of growth control and related heterostructures construction via CVD method are reviewed and discussed, including wafer-scale synthesis, phase transition, doping, alloy and stacking engineering. Meanwhile, recent progress on the application of multi-functional devices is highlighted based on 2D TMDs. Finally, challenges and prospects are proposed for the practical device applications of 2D TMDs.

The genus Paraconiothyrium has worldwide distribution with diverse host habitats and exhibits potential utilisation as biocontrol agent, bioreactor and antibiotic producer. In this review, we firstly comprehensively summarise the current taxonomic status of Paraconiothyrium species, including their category names, morphological features, habitats, and multigene phylogenetic relationships. Some Paraconiothyrium species possess vital biological functions and potential applications in medicine, agriculture, industry, and environmental protection. A total of 147 secondary metabolites have been reported so far from Paraconiothyrium, among which 95 are novel. This paper serves to provide an overview of their diverse structures with chemical classification and biological activities. To date, 27 species of Paraconiothyrium have been documented; however, only seven have been investigated for their secondary metabolites or biological functions. Our review is expected to draw more attention to this genus for providing a taxonomic reference, discovering extensive biological functions, and searching in-depth for new bioactive natural products.

Recent findings of two-dimensional (2D) ferroelectric (FE) materials provide more possibilities for the development of 2D FE heterostructure electronic devices based on van der Waals materials and the application of FE devices under the limit of atomic layer thickness. In this paper, we report the in-situ fabrication and probing of electronic structures of In2Se3–WSe2 lateral heterostructures, compared with most vertical FE heterostructures at present. Through molecular beam epitaxy, we fabricated lateral heterostructures with monolayer WSe2 (three atomic layers) and monolayer In2Se3 (five atomic layers). Type-II band alignment was found to exist in either the lateral heterostructure composed of anti-FE β′-In2Se3 and WSe2 or the lateral heterostructure composed of FE β*-In2Se3 and WSe2, and the band offsets could be modulated by ferroelectric polarization. More interestingly, interface states in both lateral heterostructures acted as narrow gap quantum wires, and the band gap of the interface state in the β*-In2Se3–WSe2 heterostructure was smaller than that in the β′-In2Se3 heterostructure. The fabrication of 2D FE heterostructure and the modulation of interface state provide a new platform for the development of FE devices.

Inspired by the great success of ultrathin two-dimensional (2D) layered crystals, more and more attention is being paid to preparing 2D nanostructures from non-layered materials. They can significantly enrich the 2D materials and 2D heterostructures family, extend their application prospects, and bring us distinct properties from their bulk counterparts due to the strong 2D confinement effect. However, the realization of 2D non-layered semiconductors with strong light-harvesting capability and the ability to construct high-performance 2D heterostructures is still a critical challenge. Herein, we successfully synthesized 2D PbSe semiconductors with a large lateral dimension and ultrathin thickness via van der Waals epitaxy. The fabricated 2D PbSe device exhibits good electrical conductivity and superior multi-wavelength photoresponse performance with high responsivity (∼10

Molybdenum disulfide (MoS2) holds great promise as atomically thin two-dimensional (2D) semiconductor for future electronics and opto-electronics. In this report, we study the magnetoresistance (MR) of MoS2 field-effect transistors (FETs) with graphene insertion layer at the contact interface. Owing to the unique device structure and high-quality contact interface, a gate-tunable linear MR up to 67% is observed at 2 K. By comparing with the MRs of graphene FETs and MoS2 FETs with conventional metal contact, it is found that this unusual MR is most likely to be originated from the contact interfaces between graphene and MoS2, and can be explained by the classical linear MR model caused by spatial fluctuation of carrier mobility. Our study demonstrates large MR responses in MoS2-based systems through heterojunction design, shedding lights for the future magneto-electronics and van der Waals heterostructures.

In this study, the secondary metabolites of a lichen-derived actinomycete strain Amycolatopsis sp. YIM 130687 were investigated intensively by using three different media (4#, 302#, and 312#) for fermentation. A total of 21 compounds were isolated from the fermented extraction of the strain. The structures of all compounds were identified by the examination of HRESIMS and NMR spectra. Compounds 1–3, 5, 6, 21 were only found in the cultivation on 302# medium, while compounds 4, 9–11 were only obtained when the strain was cultured on 312# medium. On the other hand, compounds 7, 8, and 20 were only isolated from the fermentation product on 4# medium. The antimicrobial activity test showed that compound 9 had significant inhibitory effects on bacterial pathogens of Staphylococcus aureus and MRSA with the MICs of 2 μg/ml and fungal pathogens of Botrytis cinerea and Fusarium graminearum with the MICs of 1 μg/ml.

The manipulation of magnetism provides a unique opportunity for the development of data storage and spintronic applications. Until now, electrical control, pressure tuning, stacking structure dependence, and nanoscale engineering have been realized. However, as the dimensions are decreased, the decrease of the ferromagnetism phase transition temperature (Tc) is a universal trend in ferromagnets. Here, we make a breakthrough to realize the synthesis of 1 and 2 unit cell (UC) Cr2Te3 and discover a room-temperature ferromagnetism in two-dimensional Cr2Te3. The newly observed Tc increases strongly from 160 K in the thick flake (40.3 nm) to 280 K in 6 UC Cr2Te3 (7.1 nm). The magnetization and anomalous Hall effect measurements provided unambiguous evidence for the existence of spontaneous magnetization at room temperature. The theoretical model revealed that the reconstruction of Cr2Te3 could result in anomalous thickness-dependent Tc. This dimension tuning method opens up a new avenue for manipulation of ferromagnetism.

Funding Information: This work was supported by the National Natural Science Foundation of China under grant 11875210, the Science and Technology Planning Project of Guangdong Province under grant 2018A050506082, China Postdoctoral Science Foundation under grant 2019M652687, and by the grant RFBR No.19-05-00554 in the part of the development of advanced approach to analysis of geochemical objects. In the present study Ar+ cluster ions accelerated by voltages in the range of 5-10 kV are used to irradiate single crystal ZnO substrates and nanorods to fabricate self-assembled surface nanoripple arrays. The ripple formation is observed when the incidence angle of the cluster beam is in the range of 30-70°. The influence of incidence angle, accelerating voltage, and fluence on the ripple formation is studied. Wavelength and height of the nanoripples increase with increasing accelerating voltage and fluence for both targets. The nanoripples formed on the flat substrates remind of aeolian sand ripples. The ripples formed at high ion fluences on the nanorod facets resemble well-ordered parallel steps or ribs. The more ordered ripple formation on nanorods can be associated with the confinement of the nanorod facets in comparison with the quasi-infinite surface of the flat substrates. publishersversion published

Copper chalcogenides represent a class of materials with unique crystal structures, high electrical conductivity, and earth abundance, and are recognized as promising candidates for next-generation green electronics. However, their 2D structures and the corresponding electronic properties have rarely been touched. Herein, a series of ultrathin copper chalcogenide nanosheets with thicknesses down to two unit cells are successfully synthesized, including layered Cu

The magnetic anisotropy can stabilize long-range ferromagnetic order in pristine two-dimensional (2D) crystals, which inspires the research of fundamental physics and spintronic devices based on 2D ferromagnetic materials. 2D ferromagnetic materials with intriguing magnetic properties offer an excellent platform for studying magnetism at 2D limit and exploring advanced spintronic devices. As the dimensionality decreases to 2D scale, 2D ferromagnetic materials exhibit distinctive magnetic properties compared with their bulk counterparts. In this Perspective, the recent progress and prospects of 2D ferromagnetic materials in magnetism, manipulation, and device applications are highlighted.

Liquid films created by inclined jet-wall impingement are commonly seen in industrial applications. We investigated the liquid film behaviors created by an inclined jet impinging on a vertical glass wall using a brightness-based laser-induced fluorescence method. It was found that the typical liquid film by an inclined jet-wall impingement consists of the thin layer zone, the raised zone, the liquid node, and the trailing edge. The liquid film expands with higher impingement velocity but keeps the same elliptical shape. A normalized linear correlation is proposed to estimate the liquid film thickness. Based on the continuity equation and the empirical convection model, the Reynolds number distribution is deduced from the film thickness distribution. The Reynolds number in the thin layer zone is less than the critical Reynolds number. The surface waves in the thin layer zone are divided into the ripple waves and the disturbance waves. The disturbance waves have a larger wavelength and amplitude than the ripple waves. The quantitative measurement of the disturbance waves shows that the wavelength and amplitude increase linearly along the radial distance. The smaller impingement velocity does not change the growth rate of the wavelength but accelerates the development of the amplitude.

The genus

We have developed a solid electrolyte ion source (SEIS) with CsAg4Br2.68I2.32 film deposited on a silver tip. In the paper, Ag+ ion emission was significantly enhanced and the ion current of 1.6 μA was obtained at 168 °C temperature and 20 kV accelerating voltage. I-T and I-U characteristics were well described by the field evaporation (FEV) model, and the surface potential barrier was estimated to be 0.19 eV. Experimental investigations of the Ag+ ion emission mechanisms revealed that the solid electrolyte film plays an important role of ion-transport system, and the emitted Ag+ ions were compensated by the ions diffusing from the silver reservoir (Ag-tip). The developed SEIS was exploited for the synthesis of Ag nanoparticles on Si surface. The average size of these nanoparticles was estimated 15.5 ± 0.3 nm, and the projected range Rp of the low-energy high-dose Ag+ ions implanted Si sample was found to be less than 5 nm using TOF-SIMS depth profiling. The future application of SEISs in ion propulsion systems of miniature spacecraft with limited on-board payloads was discussed, and the thrust was estimated within μN range.

In this paper, we have investigated the effects of yttrium (Y) doping on the electrical performance and stability of ZnO thin film transistors (TFTs). Here, Y-doped ZnO TFTs were fabricated by using radio frequency magnetron sputtering at 150 °C. As a result, the 1% Y-doped ZnO TFT exhibits a small threshold voltage shifts of 2.5 V under positive bias stress and −2.8 V under negative bias stress as well as desirable device performance with field effect mobility of 9.8 cm2/V s, a subthreshold swing of 320 mV/decade and on/off current ratio of 107, respectively. Based on the XPS analysis and electrical characterizations, the improvement in stability and electrical properties of ZnO TFTs were attributed to the appropriate Y doping concentration, which not only could control the carrier concentration and broaden the band gap of ZnO film, but also suppress the oxygen vacancy defects and passivate the trap density at the SiO2/ZnO interfaces. Consequently, the high stability and excellent electrical performances of Y-doped ZnO TFTs show great potential for use in flat panel displays.

Actinomycetes are regarded as important sources for the generation of various bioactive secondary metabolites with rich chemical and bioactive diversities. Amycolatopsis falls under the rare actinomycete genus with the potential to produce antibiotics. In this review, all literatures were searched in the Web of Science, Google Scholar and PubMed up to March 2021. The keywords used in the search strategy were “Amycolatopsis”, “secondary metabolite”, “new or novel compound”, “bioactivity”, “biosynthetic pathway” and “derivatives”. The objective in this review is to summarize the chemical structures and biological activities of secondary metabolites from the genus Amycolatopsis. A total of 159 compounds derived from 8 known and 18 unidentified species are summarized in this paper. These secondary metabolites are mainly categorized into polyphenols, linear polyketides, macrolides, macrolactams, thiazolyl peptides, cyclic peptides, glycopeptides, amide and amino derivatives, glycoside derivatives, enediyne derivatives and sesquiterpenes. Meanwhile, they mainly showed unique antimicrobial, anti-cancer, antioxidant, anti-hyperglycemic, and enzyme inhibition activities. In addition, the biosynthetic pathways of several potent bioactive compounds and derivatives are included and the prospect of the chemical substances obtained from Amycolatopsis is also discussed to provide ideas for their implementation in the field of therapeutics and drug discovery.

Asia, Europe, and Africa, connected by the maritime silk road (MSR) and the land silk road (LSR), as the cradle of ancient civilizations, contain rich cultural heritage resources. While aiming to achieve differentiated and targeted application, protection, and development of world cultural heritage (WCHS), it is essential to identify the temporal-spatial distribution features of WCHS on these three continents. For these WCHS elements, based on big earth data, we semi-quantitatively describe the features of spatial-temporal distribution, material types, civilization and religion characters, capital investment capacity, and risks by data cleaning, spatial analysis, and risk assessment. Our findings reveal features in these WCHS elements, including temporal and spatial distribution, the amount of different ancient civilizations and cultural diversity, and the need for preservation and funding capacity. Finally, this study’s results indicate that we should take full advantage of the potential of cultural heritage, digital technologies, and the scientific protection of cultural heritage along with the MSR and LSR. Moreover, declarations of heritage in Africa and Central Asia should be extended to realize the precise “poverty alleviation” of WCHS protection in these regions. For further planning of WCHS sites along the Silk Road, we propose countermeasures to protect the global cultural heritage in the future and also provide theoretical guidance and specific scientific implementation directions to “strengthen efforts to protect and safeguard the world’s cultural and natural heritage,” as proposed by the United Nations.

BackgroundChronic nonspecific low back pain (CNSLBP) troubles approximately 30% of people worldwide. Silver needle therapy (SNT) is a treatment method to relieve soft tissue pain through heating. Therefore, this study aimed to observe the effects of SNT on CNSLBP.MethodsIn this study, 100 patients were randomly divided into 2 groups: silver needle (SN) group and control group (n = 50). In the SN group, patients received SNT and physiotherapy, while patients received physiotherapy alone in the control group. At the 6-month follow-up, the numerical rating scale (NRS), Oswestry Disability Index (ODI), Short-Form 12 of quality of life (SF-12), the natural logarithms of low-frequency measurement (InLF), and the natural logarithms of high-frequency measurement (InHF) of heart rate variability (HRV) were recorded.ResultsIn both groups, NRS, ODI, SF-12 scores, and HRV at 2 weeks after treatment were improved and maintained for 6 months. Compared with the control group, more significant improvements were observed in the NRS and SF-12 scores at 1, 2, 3, and 6 months and in the ODI scores at 1 and 2 months in the SN group (P P ConclusionsSNT relieved pain and improved quality of life and autonomic nerve activity, especially parasympathetic nerve, in patients with CNSLBP, without serious complications.Trial registrationChinese Clinical Trial Registry No.ChiCTR-OOC-17013237. Registered on November 11, 2017.

The genus Diaporthe and its anamorph Phomopsis are distributed worldwide in many ecosystems. They are regarded as potential sources for producing diverse bioactive metabolites. Most species are attributed to plant pathogens, non-pathogenic endophytes, or saprobes in terrestrial host plants. They colonize in the early parasitic tissue of plants, provide a variety of nutrients in the cycle of parasitism and saprophytism, and participate in the basic metabolic process of plants. In the past ten years, many studies have been focused on the discovery of new species and biological secondary metabolites from this genus. In this review, we summarize a total of 335 bioactive secondary metabolites isolated from 26 known species and various unidentified species of Diaporthe and Phomopsis during 2010–2019. Overall, there are 106 bioactive compounds derived from Diaporthe and 246 from Phomopsis, while 17 compounds are found in both of them. They are classified into polyketides, terpenoids, steroids, macrolides, ten-membered lactones, alkaloids, flavonoids, and fatty acids. Polyketides constitute the main chemical population, accounting for 64%. Meanwhile, their bioactivities mainly involve cytotoxic, antifungal, antibacterial, antiviral, antioxidant, anti-inflammatory, anti-algae, phytotoxic, and enzyme inhibitory activities. Diaporthe and Phomopsis exhibit their potent talents in the discovery of small molecules for drug candidates.

In order to study the influence of the heat dissipation of the outdoor unit in the groove of the highrise building. Numerical simulation of the thermal environment of a high-rise building is carried out. The results show that: When the outdoor mean wind speed is 2.7m/s, the maximum inlet air temperature of the outdoor unit under full load condition is about 43.3 °C, which is 2 °C lower than that under no wind condition. The monsoon is beneficial to the heat dissipation of the outdoor unit. When the hot air in the building groove rises, the corner flow is induced at the lower side of the refuge layer. Due to the reverse pressure gradient, the flow separation occurs, resulting in the blockage in the flow channel. When the air flows through the refuge layer, the flow expands suddenly due to the increase of the cross-section of the channel. The turbulent boundary layer is separated. The vortex region is induced on the upper side of the refuge layer. Since the heat on the upper and lower sides of the refuge floor cannot be effectively dissipated, the inlet air temperature of the outdoor unit is higher than that of other floors, which reduces the working efficiency of the outdoor unit.

It is predicted that the conventional von Neumann computing architecture cannot meet the demands of future data-intensive computing applications due to the bottleneck between the processing and memory units. To try to solve this problem, in-memory computing technology, where calculations are carried out in situ within each nonvolatile memory unit, has been intensively studied. Among various candidate materials, 2D layered materials have recently demonstrated many new features that have been uniquely exploited to build next-generation electronics. Here, the recent progress of 2D memory devices is reviewed for in-memory computing. For each memory configuration, their operation mechanisms and memory characteristics are described, and their pros and cons are weighed. Subsequently, their versatile applications for in-memory computing technology, including logic operations, electronic synapses, and random number generation are presented. Finally, the current challenges and potential strategies for future 2D in-memory computing systems are also discussed at the material, device, circuit, and architecture levels. It is hoped that this manuscript could give a comprehensive review of 2D memory devices and their applications in in-memory computing, and be helpful for this exciting research area.

The manipulation of magnetism provides a unique opportunity for the development of data storage and spintronic applications. Until now, electrical control, pressure tuning, stacking structure dependence, and nanoscale engineering have been realized. However, as the dimensions are decreased, the decrease of the ferromagnetism phase transition temperature (

Hypersonic technology is an interdisciplinary research field, which has become the commanding point of new technology in the current aerospace field. Hypersonic vehicle is an important weapon to deal with future war and break through the missile defense system. It has great strategic deterrence significance in the military. This paper introduces the key technologies of hypersonic vehicle, such as integrated aerodynamic configuration, propulsion technology, thermal protection technology, navigation and control technology. The research status, main problems and development trends of various key technologies are summarized.

This paper investigates the effects of different passivation layers (PVLs) on the electrical performance and reliability of amorphous indium gallium zinc oxide (a-In–Ga–ZnO) thin film transistors (TFTs). By rational design, the fabricated a-InGaZnO TFT with hafnium oxide and aluminumoxide (HfO2/Al2O3) dual PVLs exhibits a field-effect mobility of 13.5 cm2/Vs, low sub threshold swing of 0.32 V/decade, and especially, small threshold voltage shifts of 0.5 (−0.6) V and 1.1 (−1.2) V under positive (negative) gate bias, and light illumination stress at the relative humidity of 40%. Furthermore, the a-In–Ga–ZnO TFTswith HfO2/Al2O3 dual PVLs maintain reasonable mobility and electrical performance even exposure to ambient condition for up to four months. This enhanced stability is attributed to the presence of high-quality HfO2/Al2O3 dual PVLs, which not only could suppress the photodesorption, reduce the total trap density and subgap photoexcitation behavior, but also protect the channel from environmental effects. Thus, the rational-designed HfO2/Al2O3 dual PVLs passivated a-In–Ga–ZnO TFTs with superior reliability represent a great step toward the achievement of long-term reliable zinc oxide-based oxide TFTs.

High-performance thin-film transistors (TFTs) were obtained by incorporating small amount of tungsten ( ${W}$ ) into amorphous indium zinc oxide (IZO)-based thin films via a solution process. Compared with original IZO TFTs, 0.2-wt% ${W}$ -doped IZO TFTs exhibit improved bias stress stability and field-effect mobility of 30.5 cm2/ $\text{V}\cdot \text{s}$ . Meanwhile, the bias stress stability of IZO TFTs can be further enhanced with 0.5-wt% W-doping. The pulsed current–voltage ( ${I}$ – ${V}$ ) method is employed to study the hysteresis and charging behavior of the ${W}$ -doped IZO TFTs. The X-ray photoelectron spectroscopy analysis and the pulsed ${I}$ – ${V}$ measurement results suggest that these desirable performances could be attributed to the suppression of excessive oxygen vacancies and improved interface quality because of ${W}$ -doping. The results represent an effective strategy to achieve high-performance solution-processed amorphous oxide-based TFTs with desirable stability by ${W}$ -doping.

An analytical review of the modern state of the development of ion sources with solid electrolytes (superionic conductors) for the aerospace and ion-beam technologies is presented. The methods for synthesis and properties of solid electrolytes, the formation of mobile ions at the “reservoir–electrolyte” interface, the fast-ion transport in a thin electrolyte film under the action of an external electric field, and the processes of ion emission (evaporation) from the surface of the electrolyte into a vacuum at a temperature below the thermionic-emission threshold and an electric-field strength that is lower than that of field-ion emitters are discussed. The operation modes, the design and manufacturing technology of anion and cation sources are described in detail. Methods for improving the performance and the main fields of application, including electrostatic rocket engines (ion microthrusters), for which a matrix solid-state ion–electron source was designed and patented, are analyzed.

Due to the Boltzmann distribution of carriers, the subthreshold swing (SS) of traditional metal–oxide–semiconductor field-effect transistors (MOSFETs) is above 60 mV/dec at room temperature. In this article, GaN-based negative capacitance field-effect transistors (NCFETs) were fabricated by introducing HfO2 /P(VDF-TrFE) stack as the gate dielectric layer. With the voltage amplification effect of the ferroelectric, the GaN NCFETs demonstrate the ultralow SS value of 36.3 mV/dec at room temperature, which also advances the MOSFETs in terms of saturation current ( $633.4~\mu \text{A}/\mu \text{m}$ ) and ON – OFF ratio ( $>{10}^{{{7}}}$ ). Therefore, this article demonstrates the feasibility of NCFETs for breaking the Boltzmann limit in III–V semiconductors-based transistors and opens up an avenue for switching electronic devices for portable applications.