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Fault diagnosis plays a crucial role in maintaining the operational safety of mechanical systems. As intelligent data-driven approaches evolve, deep learning (DL) has emerged as a pivotal technique in fault diagnosis research. However, the collected vibrational signals from mechanical systems are usually corrupted by unrelated noises due to complicated transfer path modulations and component coupling. To solve the above problems, this paper proposed the dynamic temporal denoise neural network with multi-head attention (DTDNet). Firstly, this model transforms one-dimensional signals into two-dimensional tensors based on the periodic self-similarity of signals, employing multi-scale two-dimensional convolution kernels to extract signal features both within and across periods. Secondly, for the problem of lacking denoising structure in traditional convolutional neural networks, a temporal variable denoise (TVD) module with dynamic nonlinear processing is proposed to filter the noises. Lastly, a multi-head attention fusion (MAF) module is used to weight the denoted features of signals with different periods. Evaluation on two datasets, Case Western Reserve University bearing dataset (single sensor) and Real aircraft sensor dataset (multiple sensors), demonstrates that the DTDNet can reduce the useless noises in signals and achieve a remarkable improvement in classification performance compared with the state-of-the-art method. DTDNet provides a high-performance solution for potential noise that may occur in actual fault diagnosis tasks, which has important application value. [ABSTRACT FROM AUTHOR]

Chrysanthemum, an agricultural economic crop with ornamental, medicinal, and edible values, faces the problem of continuous cropping obstacles in its cultivation. As a potential soil conditioner used to address continuous cropping obstacles (CCOs), the applicability of biochar in chrysanthemum cultivation has become a research hotspot. This study explored the effects of three different types of biochar (rice straw biochar = RB, pig manure biochar = PB, and sludge biochar = SB) on soil for chrysanthemum that had been continuously cultivated for eight years through pot experiments. The results indicate that the addition of biochar significantly reduced soil water loss. Compared with CK, the water retention rates of the SB and PB treatments increased by 25.4% and 18.4%, respectively. In the PB treatment, the contents of available phosphorus (AP) and available potassium (AK) increased by 85% and 164%, respectively. The available nitrogen (AN) content showed the highest increase under the SB treatment. All three types of biochar could improve the pH value of chrysanthemum soil with CCOs (increased by 0.4–5.4%). The results of microbial community diversity showed that, compared with CK, PB and RB slightly reduced the diversity of bacterial communities in chrysanthemum soil with CCOs (by 1.50% and 0.41%, respectively). However, the SB treatment increased the diversity of bacterial communities in chrysanthemum soil with CCOs (by 0.41%). At the same time, SB and PB significantly inhibited the diversity of fungal communities (reduced by 15.15% and 6.67%, respectively), while RB promoted the diversity of fungal communities (increased by 5.45%). Furthermore, the analysis results of bacterial phyla and genera indicated that PB and SB had enhancing effects on the beneficial bacterial phylum Actinobacteriota (8.66% and 4.64%) and the beneficial bacterial genus Nocardioides (23.29% and 9.69%). Additionally, the PB treatment enhanced the beneficial bacterial phylum Firmicutes (7.03%). The analysis results of fungal genera and phyla indicated that PB contributed to an increase in the beneficial fungal phylum Ascomycota (1.51%). RB significantly enhanced the beneficial fungal genus Chaetomium (56.34%). Additionally, all three types of biochar effectively reduced the abundance of the harmful fungal phylum Basidiomycota (30.37–73.03%). In the PB and SB treatments, the harmful fungal phylum Mucoromycota was significantly decreased (by 36.22% and 62.60%, respectively). Finally, all three types of biochar reduced the abundance of harmful fungal genera Acremonium (1.15–35.19%) and Phoma (97.1–98.7%). In this study, we investigated the effect of three kinds of biochar (RB, PB, and SB) on the soil of chrysanthemum continuous cropping through potting experiments and found that they could significantly reduce water loss, enhance water retention, increase the soil nutrient content, improve the pH value, regulate microbial communities, increase beneficial microorganisms, and reduce harmful microorganisms. These results provide a scientific basis for addressing barriers to continuous cropping (CC) while supporting the sustainability of agriculture and the development of agroecology. [ABSTRACT FROM AUTHOR]

The transverse leakage of leaky surface acoustic waves (LSAWs) occurs on 42°YX-lithium tantalate substrates (42LT), which increases the insertion loss, narrows the bandwidth and flattens the roll-off of band 40/41 SAW filters and duplexers. In this work, LSAW characteristics with different metal materials and thicknesses are calculated by the finite element method (FEM), which determines the IDT material and thickness used for band 40/41 SAW filter design. To deeply understand transverse leakage and suppress it, the effects of different gap and dummy lengths on transverse leakage are simulated and discussed. Then, a new technique of using a wider dummy without any additional lithographic or depositing processes is proposed to suppress the leakage. Its effectiveness is validated by both simulations and experiments. Then, the technique is extended to applications of band 40 and 41 SAW filters. The experimental results show that with the wider dummy structure, the band 40 and 41 SAW filters achieve a more than 0.2 dB improvement in the insertion loss, a wider bandwidth and a steeper roll-off characteristic. This technique may also be extended to the other band SAW filter applications. [ABSTRACT FROM AUTHOR]

The development of 5G mobile communication imposes requirements of high frequency, miniaturization, and integration on surface acoustic wave devices. Compared with traditional piezoelectric bulk single crystal material, surface acoustic wave filters fabricated with silicon-based piezoelectric single crystal film materials exhibit advantages such as high frequency, low insertion loss, high temperature stability and so on, making silicon-based piezoelectric single crystal film material prime foundation material. Smart-Cut™ is the universal method for preparing silicon-based piezoelectric single crystal film materials, and bonding process is one of the most essential procedures. Bonding quality determines the quality of piezoelectric single crystal film and ultimately affects the performance of the devices. In this work, high-quality heterogeneous silicon-based LiTaO3 wafers with the bonding strength up to 1. 84 J/m² and bonding area over 99. 9% were achieved through optimizing low-temperature direct bonding process, which includes plasma activation, megasonic cleaning, pre-bonding, and thermal treatment. [ABSTRACT FROM AUTHOR]

Carbon dioxide is one of the greenhouse gases responsible for global warming, and how to reduce the amount of carbon dioxide in the air is a major issue. Scholars have found that herbaceous flowers can fix 12.16 g•m-2• D-1 carbon dioxide per unit leaf area in green space, which has a good ecological benefit of carbon sequestration. Therefore, how to further improve the ecological benefits of carbon sequestration has become a concern of landscape architecture industry. This paper summarizes seven kinds of garden green land carbon ecological concrete approaches to improve, including selecting high carbon sequestration ability of plant species, increase high carbon sequestration ability of plant population, rich garden plant hierarchy, increase use native plants, increasing the vertical greening, choose low maintenance plants landscape, choose the appropriate maintenance management way, In order to deal with global warming phenomenon on the full play of green landscape fixed carbon dioxide capacity.

SAW devices with a multi-layered piezoelectric substrate have excellent performance due to advantages such as a high quality factor, Q, low loss insertion, large bandwidth, etc. Prior to manufacturing, a comprehensive analysis and proper design are essential to evaluating the device's key performance indicators, including the Bode Q value, bandwidth, and transverse mode suppression. This study explored the performance of SAW resonators employing a 42°Y-X LiTaO3 (LT) thin-plate-based multi-layered piezoelectric substrate. The thicknesses for each layer of the 42°Y-X LT/SiO2/poly-Si/Si substrate were optimized according to the index of phase velocity, Bode Q value, and bandwidth. The effect of the device structure parameters on the dispersion curve and slowness curve was studied, and a flat slowness curve was found to be favorable for transverse mode suppression. In addition, the design of the dummy configuration was also optimized for the suppression of spurious waves. Based on the optimized design, a one-port resonator on the 42°Y-X LT/SiO2/poly-Si/Si substrate was fabricated. The simulation results and measurements are presented and compared, which provides guidelines for the design of new types of SAW devices configured with complex structures. [ABSTRACT FROM AUTHOR]

The Baeyer–Villiger oxidation (BVO) of ketone and aldehyde can produce ester and formate, which both have wide applications in many areas. In this work, a series of Sn-containing silicates were prepared through the sol-gel process by using structure-directing and crystallizing agents and post-synthetic coordinated modification of binaphthol. Characterizations revealed that loading of (L)-sodium lactate as the crystallizing agent decreased the crystal size of the synthesized catalyst, and there were SnO2 nanoparticles with sizes of 17–19 nm on the catalyst. Furthermore, quite differently from the 3D mesoporous structure of classical Sn-beta zeolites, the synthesized catalysts had a silt-like mesoporous structure. In the catalysis, when cyclic aliphatic ketones were used as the substrate, only BVO-type products and corresponding ring-opening products were obtained. BVO of aliphatic aldehyde produced both an aerobic oxidation product (carboxylic acid) and a BVO-type product. The presented transformation of aromatic aldehyde (benzaldehyde) only gave an aerobic oxidation product (benzoic acid). The post-synthetic coordinating attachment of (S)-binaphthol to the Sn-containing silicate backbone worsened the BVO of aliphatic ketones but improved the BVO of aliphatic aldehyde and the aerobic oxidation of aromatic aldehyde. In addition, this work also developed two new routes for the synthesis of high-value-added 6-hydroxyhexanoic acid and cyclohexylformate under catalytic BVO conditions. [ABSTRACT FROM AUTHOR]

The Baeyer-Villiger Oxidation (BVO) of ketones and aldehydes produce lactones and formates, while aerobic carboxylation of aldehydes manufactures carboxylic acids, both having high added value. This work prepared a series of Al-containing silicates modified with organic ligands and SnO2 nanoparticles, which were then employed as catalyst in BVO and carboxylation. Characterizations revealed the morphology of the synthesized catalyst was changed from micron-sized thin sheets to smaller blocks, and then to uniform nanoparticles (size of 50 nm) having the doped SnO2 nanoparticles with a size of 29 nm. All catalysts showed high BET surface areas featuring silt-like mesopores. In determining the priority of BVO and carboxylation, an influence evaluation of the parameters showed the order to be substrate > oxidant > solvent > catalyst. Cyclic aliphatic ketones were suitable for BVO, but linear aliphatic and aromatic aldehydes for carboxylation. Coordination of (S)-binaphthol or doping of Sn into catalyst showed little influence on BVO under m-CPBA, but the Sn-doped catalyst largely increased BVO under (NH4)2S2O8 and H2O2. Calculations revealed that the catalyst containing both Al and Sn could give BVO intermediates lower energies than the Sn-beta zeolite model. The present system exhibited merits including wider substrate scope, innocuous catalytic metal, greener oxidant, as well as lower catalyst cost. [ABSTRACT FROM AUTHOR]

To ensure that the performance of filters matches the continuous development in communication frequency bands, the influence of temperature on filter performance must be considered during the fabrication of filters. In this study, a cavity-type temperature-compensated film bulk acoustic resonator (TC-FBAR) device was prepared with an SiO2 temperature filter between the bottom electrode and the piezoelectric layer. A one-dimensional Mason model of the TC-FBAR was established. An advanced design system, a high-frequency structure simulator, and COMSOL software were used to optimize the design of the TC-FBAR. After the optimization, the out-of-band rejection was improved by 10 dB. To address the compensation effect of the tensile and compressive stresses, a multilayer film was implemented for low-stress control and a reduction in stress to |P| ≤ 150 MPa, thereby improving the orientation of the piezoelectric film. Moreover, the influence of the thickness of the SiO2 temperature-compensated layers on the temperature-compensated characteristics was studied. When the SiO2 thickness was 50 nm, the temperature coefficient of frequency (TCF) was ±1 ppm/°C. The center frequency and 3 dB bandwidth of TC-FBAR were 2.492 GHz and 15.02 MHz, respectively, and the center insertion loss was −3.1 dB. Moreover, the out-of-band rejection was greater than 40 dBc, and TCF was 0.8 ppm/°C. [ABSTRACT FROM AUTHOR]

A new fault detection scheme for aircraft Inertial Measurement Unit (IMU) sensors is developed in this paper. This scheme adopts a deep neural network with a CNN-LSTM-fusion architecture (CNN: convolution neural network; LSTM: long short-term memory). The fault detection network (FDN) developed in this paper is irrelative to aircraft model or flight condition. Flight data is reformed into a 2D format for FDN input and is mapped via the net to fault cases directly. We simulate different aircrafts with various flight conditions and separate them into training and testing sets. Part of the aircrafts and flight conditions appears only in the testing set to validate robustness and scalability of the FDN. Different architectures of FDN are studied, and an optimized architecture is obtained via ablation studies. An average detecting accuracy of 94.5% on 20 different cases is achieved. [ABSTRACT FROM AUTHOR]

Liquid crystalline (LC) diblock copolymers containing a side-on LC block and a pseudo-stilbene azobenzene block were synthesized, and their self-assembling in water/tetrahydrofuran (THF) was investigated. Side-on LC monomer 4"-methylacryloyloxybutyl 2,5-di(4'-butyloxybenzoyloxy) benzoate (4-MDBB) was synthesized, and then polymerized into P4MDBB through reversible addition-fragmentation chain transfer (RAFT) polymerization. A pseudo-stilbene azobenzene monomer 6-(N-methyl-N-(4-(4'-cyanophenylazo)phenyl)amino)hexyl methacrylate (6-NCN) was also synthesized. The diblock copolymers P4MDBBm-b-P6NCNn were obtained through the RAFT polymerization of 6-NCN by using P4MDBB as the chain transfer agent. The copolymers and the intermediates were confirmed by 1H and 13C NMR spectra, FT-IR spectra, UV-Vis spectra, mass spectra, DSC analysis, POM observations, GPC tests and contact angle measurements. The diblock copolymers self-assembled upon adding water slowly into their THF solutions. The self-assembling and the corresponding assemblies were characterized by fluorescence spectra, laser light scattering experiments as well as TEM measurements. Results demonstrated that these diblock copolymers form spherical aggregates in water/THF, but the aggregates are un-stretchable upon irradiation with polarized light. [ABSTRACT FROM AUTHOR]

The method of determining concrete fracture energy recommended by RILEM has an obvious size effect, so determining fracture energy that is unaffected by size of the test specimen is difficult. In this study, 60 high-strength concrete single-edge notched beams (SENBs) of different sizes, crack length-to-depth ratios, and span-to-depth ratios were subjected to the three-point loading test as recommended by RILEM. Then, the influences of the boundary effect on the fracture energy were identified. Based on the SENB boundary effect model, a piecewise function of the interrelationships between the experimental test fracture energy Gf, the local fracture energy gf, and the fracture energy unaffected by specimen size GF was established. The applicability of the boundary effect model was verified using the test results from this study and from the previously published research. The results show that the local fracture energy distribution in the boundary influence region was nonuniform. The smaller the local fracture energy was, the closer it was to the rear boundary of the specimen. The influence length al∗ of the boundary increased with the increasing specimen size. Based on the bilinear distribution model of the local fracture energy gf, the fracture energy unaffected by beam size GF can be obtained according to the fracture energy Gf measured for laboratory-scale small-sized SENB specimens. Furthermore, the model predictions are in good agreement with experimental observations. [ABSTRACT FROM AUTHOR]

Green roofs have increasingly been designed and applied to relieve environmental problems, such as water loss, air pollution as well as heat island effect. Substrate and vegetation are important components of green roofs providing ecosystem services and benefiting the urban development. Biochar made from sewage sludge could be potentially used as the substrate amendment for green roofs, however, the effects of biochar on substrate quality and plant performance in green roofs are still unclear. We evaluated the effects of adding sludge biochar (0, 5, 10, 15 and 20%, v/v) to natural soil planted with three types of plant species (ryegrass, Sedum lineare and cucumber) on soil properties, plant growth and microbial communities in both green roof and ground ecosystems. Our results showed that sludge biochar addition significantly increased substrate moisture, adjusted substrate temperature, altered microbial community structure and increased plant growth. The application rate of 10–15% sludge biochar on the green roof exerted the most significant effects on both microbial and plant biomass by 63.9–89.6% and 54.0–54.2% respectively. Path analysis showed that biochar addition had a strong effect on microbial biomass via changing the soil air-filled porosity, soil moisture and temperature, and promoted plant growth through the positive effects on microbial biomass. These results suggest that the applications of biochar at an appropriate rate can significantly alter plant growth and microbial community structure, and increase the ecological benefits of green roofs via exerting effects on the moisture, temperature and nutrients of roof substrates. [ABSTRACT FROM AUTHOR]

The relationship between the structure and the dielectric properties of the azo polymers was studied. Four azo polymers were synthesized through the azo-coupling reaction between the same precursor (PAZ) and diazonium salts of 4-aminobenzoic acid ethyl ester, 4-aminobenzonitrile, 4-nitroaniline, and 2-amino-5-nitrothiazole, respectively. The precursor and azo polymers were characterized by 1H NMR, FT-IR, UV-vis, GPC, and DSC. The dielectric constant and dielectric loss of the samples were measured in the frequency range of 100 Hz–200 kHz. Due to the existence of the azo chromophores, the dielectric constant of the azo polymers increases compared with that of the precursor. In addition, the dielectric constant of the azo polymers increases with the increase of the polarity of the azo chromophores. A random copolymer (PAZ-NT-PAZ) composed of the azo polymer PAZ-NT and the precursor PAZ was also prepared to investigate the content of the azo chromophores on the dielectric properties of the azo polymers. It showed that the dielectric constant increases with the increase of the azo chromophores. The results show that the dielectric constant of this kind of azo polymers can be controlled by changing the structures and contents of azo chromophores during the preparation process. [ABSTRACT FROM AUTHOR]

In this study, a series of liquid crystalline diblock copolymers, composed of a soft poly(dimethylsiloxane) (PDMS) block with a defined length and a side-on liquid crystalline poly(3ʹʹ-acryloyloxypropyl 2,5-di(4ʹ-butyloxybenzoyloxy) benzoate) (P3ADBB) block with different lengths, are synthesised by the atom transfer radical polymerisation. The macromolecular structures, liquid crystalline properties and the microphase-separated morphologies of the diblock copolymer are investigated by1H NMR, FT-IR, GPC, POM, DSC and TEM. The results show that the well-defined diblock copolymers (PDMSn-b-P3ADBBm) possess four different soft/rigid ratios (n = 58,m = 10, 25, 42, 66) and relatively narrow molecular distributions (PDI ≤ 1.30). P3ADBB blocks of the copolymers show nematic sub-phases, which are identical to the mesomorphic behaviour of the homopolymer P3ADBB. After being annealed at 90°C in a vacuum oven for 48 h, the copolymers form a lamellar morphology whenm = 10 and morphologies of PDMS spheres embedded in P3ADBB matrix whenm = 25, 42 and 66. [ABSTRACT FROM AUTHOR]

In this study, the dielectric properties of poly(arylene ether nitrile) (PEN) were effectively improved by the incorporation of conducting polyaniline (PANI). Sulfuric acid doped PANI was prepared and incorporated into the PEN matrix as additives by using the solution-casting method. The micro-morphologies, mechanical, thermal and dielectric properties of the obtained PANI/PEN nanocomposites were investigated in detail. SEM observation showed that the PANI phase is homogeneously dispersed in the PEN matrix. The obtained PANI/PEN nanocomposites showed good thermal stability as the glass transition temperatures and initial decomposition temperatures of them are higher than 190 and 270 °C. The dielectric constant of the composites was significantly improved after the introduction of PANI, and the dielectric constant of the composite PANI/PEN100 reaches 23.5 (250 Hz), with an increment of 650 % when 10 wt% of PANI is introduced. The temperature dependencies of dielectric constant measurement showed that the dielectric constant of the PANI/PEN composites is stable before 180 °C and these composites can be long-term used at high temperature for their good reversibility and robustness during the heating and cooling scans. These PANI/PEN composites will be a potential candidate as high performance electronic devices materials used at high temperature. [ABSTRACT FROM AUTHOR]

ABSTRACT In this study, we report the synthesis, characterization, and photo-responsive properties of a new Y-shaped amphiphilic azo triblock copolymer composed of two isotropic polyethylene glycol (PEG) blocks and an azobenzene liquid crystalline block. The azo block, with two ending groups suitable for the azo coupling reaction, is polymerized by atom transfer radical polymerization with a synthesized initiator containing two functional terminal groups. The macromolecular diazonium salts are prepared by the diazotization of PEG terminated with an amino group. The triblock copolymer is obtained by the azo coupling reaction between the azo block and macromolecular diazonium salts in DMF under mild condition. The intermediates and the obtained triblock copolymer are characterized by 1H NMR, FT-IR, GPC, POM, DSC, TEM, and UV-vis. The photoinduced isomerization behavior of the azo copolymer is investigated by UV-vis. With the addition of water into the solution of the triblock copolymer, spherical aggregates with an average diameter of about 400 nm can be easily obtained. The aggregates are elongated when irradiated with polarized 365 nm UV light. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43695. [ABSTRACT FROM AUTHOR]

A new polysiloxane polymer as a coating material for surface acoustic wave (SAW) sensors was synthesized. The polymer was a linear polysiloxane functionalized with hexafluoroisopropanol (HFIP) groups, poly{methyl [4-(hexafluoroisopropanol) phenylethyl] siloxane}. The polymer was spin-coated on a 200-MHz SAW sensor for the detection of a 2,4-dinitrotoluene vapor. A fast response time of 30 s and good reproducibility were achieved. It was found that the frequency shift decreased as the polymer concentrations decreased. The new polysiloxane coatings showed excellent properties, such as a high sensitivity, high permeability, and low glass-transition temperature (−40.5 ± 1°C). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 [ABSTRACT FROM AUTHOR]

Radio-frequency (RF) surface acoustic wave (SAW) resonators used as filters and duplexers are mass-produced and widely used in current mobile phones. With the numerous emergences of the diverse device structure, a universal method used for the accurate and fast simulation of the SAW resonator calls for urgent demand. However, there are too many instances where the behavior of the entire acoustic resonator cannot be characterized rapidly and efficiently due to limitations in the current computer memory and speed. This is especially true for SAW resonators configured with long arrays of inter-digital transducers (IDTs), and we have to resort to a periodic analysis. In this paper, the previously reported generalized partial differential equations (PDE) based on the two-dimensional finite element method (2D-FEM) model is extended to analysis for the periodic structure of the SAW resonator. We present model order reduction (MOR) techniques based on FEM and periodic boundary conditions to achieve a dimensionally reduced PDE model without decreasing the accuracy of computations. Examples of different SAW devices, including the regular SAW, IHP-SAW and TC-SAW resonators, are provided which shows the results of the periodic analysis compared with the experimental results of the actual resonators. The investigation results demonstrate the properties of the proposed methodology and prove its effectiveness and accuracy. [ABSTRACT FROM AUTHOR]

A series of polymers containing nunchaku-like unit with an azo chromophore and a mesogen group was successfully prepared and photoinduced anisotropy of the obtained polymers was minutely investigated. Firstly, monomers containing nunchaku-like unit with an azo chromophore and a mesogen group linked by flexible group were synthesized. The structure of the monomers was confirmed via NMR COSY spectra. Subsequently, the obtained monomers were polymerized into corresponding polymers through RAFT polymerization. The prepared polymer samples were characterized through NMR, FTIR, gel permeation chromatography (GPC), and UV-vis testing while the thermal properties of the samples were investigated through differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA) measurements. The photoinduced isomerization of the polymers, which was researched in situ via measuring UV-vis spectra of the polymer solutions and spin-coated films under irradiation with 450 nm light or putting in darkness, demonstrated the rapid trans-cis-trans isomerization of the polymers. When irradiated with a linearly polarized light, significant photoinduced birefringence and dichroism were observed, suggesting photoinduced isomerization of azobenzene can drive orientation of mesogen in the system. This study blazes a way to design the optical materials with light-controllable birefringence and dichroism. [ABSTRACT FROM AUTHOR]

Green roofs can improve urban ecological conditions by mitigating the heat island effect and absorbing harmful gases. Soil additives can improve roof soil properties and promote the stability of the urban ecosystem. As soil additives, biochar and sludge are widely used in the ground, but their application on roofs is still scarce. This study examined the carbon storage potential of green roofs amended with sludge and biochar. The roof soil was composed of soil and varying proportions of the additives (0%, 5%, 10%, 15%, and 20%, v/v); Sedum lineare was then planted. The carbon contents of the soils and plants were measured for one year. The influence of biochar or sludge on the carbon content of the roof soil and the factors affecting the roof carbon storage potential were analyzed. The results showed that the carbon storage potential of a biochar green roof (9.3 kg C m−2) was significantly higher than that of a sludge green roof (7.9 kg C m−2). Biochar increased the carbon content of the green roof by improving the physical properties of the roof soil and promoting plant growth, whereas sludge increased the carbon content of the green roof by improving the chemical properties of the roof soil. Moreover, biochar could not only store large amounts of stable carbon, but also reduce the weight of the green roof, improve soil moisture, and provide a resourceful utilization of municipal sludge. Thus, biochar can be considered a material for promoting carbon storage on green roofs. [ABSTRACT FROM AUTHOR]

The sensing property and mechanism of surface acoustic wave (SAW) humidity sensors based on sol–gel SiO 2 films were investigated. The SiO 2 films were fabricated with a sol–gel method. The SEM, AFM, and porosity investigations showed that the SiO 2 films had a porous structure with a porosity of 53.4%. Through a comparative study between SAW type and resistive type humidity sensors based on semi-conducting oxide (ZnO, Co 3 O 4 , CuO, TiO 2 ) and SiO 2 films, it was found that not only the change of film conductivity (electric loading effect) but also the change of mass loading on the films (mass loading effect) contributed to the response of SAW humidity sensors when the RH (relative humidity) value changed. Moreover, the mass loading effect made the major contribution to the responses of SAW humidity sensors based on SiO 2 films due to the films’ porous structure. Consequently, the sensors based on SiO 2 films showed much higher responses, and the responses increased with the increase of the thickness of SiO 2 films. The sensor with the thickest SiO 2 film (∼230 nm) showed a response of −520 kHz when the RH value increased from 30% to 93%. [ABSTRACT FROM AUTHOR]

• PPy/N-MWCNT gas sensor after annealing treatment was synthesized for NO 2 sensing. • The response of optimal hybrids exhibited 44.12 times than that of unannealed one. • The effect of annealing treatment on NO 2 sensing was discussed. A flexible NO 2 gas sensor based on a polypyrrole/nitrogen-doped multi-walled carbon nanotube (PPy/N-MWCNT) composite film was successfully prepared on PI substrates using a combined in situ self-assembly and annealing treatment method. After annealing at 350 °C, the gas sensor exhibited a high response of 24.82% ((R g −R a)/R a ×100%) under 5 ppm of NO 2 , which is 44.12 times greater than that of the unannealed sensor. The PPy/N-MWCNT gas sensor exhibited excellent repeatability, remarkable selectivity, good long-term stability, and acceptable flexibility. Furthermore, the effect of the relative humidity on the gas sensing properties was examined. The excellent gas sensing performances of the sensor were attributed to the enriched adsorption sites due to degradation of the amount of stacked PPy structures on the surface of the N-MWCNTs after the annealing treatment. The results demonstrated that PPy/N-MWCNT composite films are highly promising for potential applications in the field of NO 2 gas sensing. [ABSTRACT FROM AUTHOR]

SAW devices with a multi-layered piezoelectric substrate have excellent performance due to advantages such as a high quality factor, Q , low loss insertion, large bandwidth, etc. Prior to manufacturing, a comprehensive analysis and proper design are essential to evaluating the device's key performance indicators, including the Bode Q value, bandwidth, and transverse mode suppression. This study explored the performance of SAW resonators employing a 42°Y-X LiTaO 3 (LT) thin-plate-based multi-layered piezoelectric substrate. The thicknesses for each layer of the 42°Y-X LT/SiO 2 /poly-Si/Si substrate were optimized according to the index of phase velocity, Bode Q value, and bandwidth. The effect of the device structure parameters on the dispersion curve and slowness curve was studied, and a flat slowness curve was found to be favorable for transverse mode suppression. In addition, the design of the dummy configuration was also optimized for the suppression of spurious waves. Based on the optimized design, a one-port resonator on the 42°Y-X LT/SiO 2 /poly-Si/Si substrate was fabricated. The simulation results and measurements are presented and compared, which provides guidelines for the design of new types of SAW devices configured with complex structures.

Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Single-domain antibody (sdAb) holds the promising strategies for diverse research and translational applications. Here, we describe a method for the adaptation of the in situ proximity ligation assay ( is PLA) followed by sequencing ( is PLA-seq) to facilitate screening of a high-sensitive, high-throughput sdAb library for a given protein at subcellular and single-cell resolution. Based on the sequence of complementarity-determining region 3 (CDR3), the recombinant sdAb can be produced for in vitro and in vivo utilities. This method provides a general means to identify the functional measure of sdAb and its complementary epitopes and its potential applications to investigate cellular processes., (© 2021 Yin et al.)

Using a seed layer-free hydrothermal method, ZnO nanorods (NRs) were deposited on ST-cut quartz surface acoustic wave (SAW) devices for ammonia sensing at room temperature. For a comparison, a ZnO film layer with a thickness of 30 nm was also coated onto an ST-cut quartz SAW device using a sol-gel and spin-coating technique. The ammonia sensing results showed that the sensitivity, repeatability and stability of the ZnO NR-coated SAW device were superior to those of the ZnO film-coated SAW device due to the large surface-to-volume ratio of the ZnO NRs., Competing Interests: The authors declare no conflicts of interest.