High-order mode working terahertz radiation source based on narrow-band Smith-Purcell radiation in a closed structure.

In this paper, we use the method of high order TMn1 mode selection from the concept of narrow-band Smith-Purcell radiation (SPR) for powerful, over-mode, multi-gap extended interaction circuit designs toward millimeter wave and Terahertz (THz) region. As a core part, the multiple gaps interaction structure, equivalent to a subwavelength hole array (SHA), excites the narrow band SPR when an electron beam is injected. The SPR energy is collected by a pair of closed cavities, which satisfies (n-1) standing wave units. The SPR energy in the optimized cavity allows a high index n TMn1 mode operation to achieve the strongest Ez field and high characteristic impedance in a closed multi-gap resonant circuit. This provides an effective design to establish a stable high-order TMn1 mode that supports extended interaction circuits with large cross sections. A 0.46 THz extended interaction circuit, employing the novel high order TM51-2π mode operation output structure, has been designed to demonstrate the efficient beam-wave interaction in the proposed system. The method of TMn1 mode selection provides new insight into the understanding of the high-frequency extended interaction circuits by introducing the SPR concept, benefiting the development of millimeter wave and THz vacuum electron devices (VEDs).

Halide Double Perovskite Nanocrystals Doped with Rare-Earth Ions for Multifunctional Applications.

Most lead-free halide double perovskite materials display low photoluminescence quantum yield (PLQY) due to the indirect bandgap or forbidden transition. Doping is an effective strategy to tailor the optical properties of materials. Herein, efficient blue-emitting Sb3+ -doped Cs2 NaInCl6 nanocrystals (NCs) are selected as host, rare-earth (RE) ions (Sm3+ , Eu3+ , Tb3+ , and Dy3+ ) are incorporated into the host, and excellent PLQY of 80.1% is obtained. Femtosecond transient absorption measurement found that RE ions not only served as the activator ions but also filled the deep vacancy defects. Anti-counterfeiting, optical thermometry, and white-light-emitting diodes (WLEDs) are exhibited using these RE ions-doped halide double perovskite NCs. For the optical thermometry based on Sm3+ -doped Cs2 NaInCl6 :Sb3+ NCs, the maximum relative sensitivity is 0.753% K-1 , which is higher than those of most temperature-sensing materials. Moreover, the WLED fabricated by Sm3+ -doped Cs2 NaInCl6 :Sb3+ NCs@PMMA displays CIE color coordinates of (0.30, 0.28), a luminous efficiency of 37.5 lm W-1 , a CCT of 8035 K, and a CRI over 80, which indicate that Sm3+ -doped Cs2 NaInCl6 :Sb3+ NCs are promising single-component white-light-emitting phosphors for next-generation lighting and display technologies.

A meta-analysis on morphological, physiological and biochemical responses of plants with PGPR inoculation under drought stress.

Plant growth-promoting rhizobacteria (PGPR) can help plants to resist drought stress. However, the mechanisms of how PGPR inoculation affect plant status under drought remain incompletely understood. We performed a meta-analysis of plant response to PGPR inoculation by compiling data from 57 PGPR-inoculation studies, including 2, 387 paired observations on morphological, physiological and biochemical parameters under drought and well-watered conditions. We compare the PGPR effect on plants performances among different groups of controls and treatments. Our results reveal that PGPR enables plants to restore themselves from drought-stressed to near a well-watered state, and that C4 plants recover better from drought stress than C3 plants. Furthermore, PGPR is more effective underdrought than well-watered conditions in increasing plant biomass, enhancing photosynthesis and inhibiting oxidant damage, and the responses of C4 plants to the PGPR effect was stronger than that of C3 plants under drought conditions. Additionally, PGPR belonging to different taxa and PGPR with different functional traits have varying degrees of drought-resistance effects on plants. These results are important to improve our understanding of the PGPR beneficial effects on enhanced drought-resistance of plants.

Research Progress on Inactivation of Bacteriophages by Visible-Light Photocatalytic Composite Materials: A Mini Review.

Infectious diseases caused by waterborne viruses have attracted researchers' great attention. To ensure a safe water environment, it is important to advance water treatment and disinfection technology. Photocatalytic technology offers an efficient and practical approach for achieving this goal. This paper reviews the latest studies on visible-light composite catalysts for bacteriophage inactivation, with a main focus on three distinct categories: modified UV materials, direct visible-light materials and carbon-based materials. This review gives an insight into the progress in photocatalytic material development and offers a promising solution for bacteriophage inactivation.

Particle Characterization of Manufactured Sand and Its Influence on Concrete Properties.

With the rapid development of infrastructure construction, it is an inevitable trend to replace natural sand in short supply with manufactured sand to meet sustainable development. In this paper, the relationship between the particle shape characteristics of manufactured sand and concrete performance is discussed using a morphological analysis and concrete experiments. The particle shape parameters of five types of manufactured sand were obtained by using the aggregate image measurement system (AIMS) and digital image processing (DIP) techniques, and the correlations between different parameters were analyzed. Moreover, the properties of concrete with the five kinds of manufactured sand were tested. The results show that particle size and type have a significant impact on particle shape parameters. Particle shape parameters, especially angularity, correlate well with the workability and compressive strength of concrete while having little effect on the durability of concrete. An accurate understanding of the morphological characteristics of manufactured sand is conducive to the optimization of concrete mix designs. Therefore, it is suggested that a manufactured-sand shape test be included in aggregate specification.

Comparative study on intercalation-exfoliation and thermal activation modified kaolin for heavy metals immobilization during high-organic solid waste pyrolysis.

With the new municipal solid waste classification policy implemented in China, attention on achieving the waste-to-energy disposal of "dry waste" has been growing. Pyrolysis conversion of organic waste into value-added chemicals is a promising method to treat solid waste. However, after removing the non-combustible components of "dry waste", the obtained high-organic solid waste (HSW) contains various heavy metals, which requires urgent attention during thermochemical conversion. To mitigate heavy metals risk, kaolin was employed as additive during HSW pyrolysis, and intercalation-exfoliation and thermal activation modifications were performed on the kaolin to further immobilize and stabilize heavy metals in the derived chars. The characterization results illustrated that the interlayer spacing, pore volume and diameter of kaolin were expanded after intercalation-exfoliation modification, providing more opportunities for the adsorption of metals. The thermal activation method favored the transformation of kaolin into metakaolin via dehydroxylation to enhance its nonhexacoordinated Al proportion and chemisorption. During 450-650 °C, kaolin exhibited an effective solid enrichment performance for targeting heavy metals, and the intercalation-exfoliation and thermal activation modification further enhanced the adsorption capacity of the kaolin for Cd, Cr, Pb and Cr, Cu, Pb, Zn, respectively. Compared with Cu and Zn, additives demonstrated better stabilization effects for Cd, Pb, and Cr, transforming more bioavailable fractions to the residual speciation. Overall, a higher pyrolytic temperature (650 °C) and the addition of effective additives could simultaneously increase the residual fraction and decrease the bioavailable fraction of heavy metals in HSW-derived chars, reducing the potential ecological risk.

Smith-Purcell radiation based on the transmission enhancement of a subwavelength hole array with inner tunnels.

The use and control of the extraordinary optical transmission through subwavelength hole arrays has enormous application potential in photonic devices. In this paper, we propose a subwavelength hole array with inner tunnels, for which the Smith-Purcell radiation (SPR) with this enhanced transmission phenomenon in THz is excited when the transmission peak locates in the SPR band. The SPR is monitored using particle-in-cell simulations in order to analyze the mechanisms responsible for improving the radiation coherence. Analysis of the electron energy loss reveals that the proposed subwavelength hole array with inner tunnels outperforms a conventional subwavelength grating array with respect to SPR generation efficiency. As SPR plays a significant role in research on particle diagnosis and terahertz radiation sources, the performance of the proposed structure suggests that it has high application potential.

Different tillage practices change assembly, composition, and co-occurrence patterns of wheat rhizosphere diazotrophs.

Tillage has a considerable effect on the soil ecosystem and its services, including microbial communities. Harnessing beneficial microbes is a sustainable way to optimizing crop management and agricultural production. Although diazotrophs play a major role in global biological nitrogen fixation, the effects of tillage on diazotrophic communities in the rhizosphere are not fully understood. In the present study, we investigated the diazotrophic community in wheat rhizosphere soil under different tillage treatments in a long-term experiment, i.e., plow tillage (considered as conventional tillage), chisel plow tillage (considered as conservation tillage), and zero tillage (considered as conservation tillage). Tillage led to a divergent distribution in the rhizosphere diazotrophic community and significant changes in community structure. Tillage caused specific responses from members/modules of the rhizosphere diazotrophic community co-occurrence network, and the relative abundance of keystone taxa was higher under conservation tillage than under conventional tillage. The increased abundance of tillage-sensitive modules under conservation tillage had a broad and significant positive correlation with rhizosphere nutrient availability, whereas the opposite was true for conventional tillage. Differences in nutrients under different tillage practices may lead to different assembly processes of diazotrophs. Overall, our findings indicate that tillage significantly affects the assembly and composition of the rhizosphere diazotrophic community, emphasizing the importance of improved substrate availability for rhizosphere diazotrophic modules under conservation tillage. This knowledge could deepen our understanding of the rhizosphere functional microbial community (e.g., biological nitrogen fixation).

Eukaryotic community diversity and pathogenic eukaryotes in a full-scale drinking water treatment plant determined by 18S rRNA and metagenomic sequencing.

In this study, 18S rRNA high-throughput sequencing was applied to investigate the eukaryotic community in a full-scale drinking water treatment plant. Eukaryotic species and microbial functions in raw water and filter biofilms were identified by metagenomic sequencing. The eukaryotic species richness and diversity presented declining trends throughout the treatment process. The lowest eukaryotic species richness was observed in disinfected water. Arthropoda, Ciliophora, Ochrophyta, and Rotifera were the dominant eukaryotic phyla and exhibited high variations in relative abundance among the different treatment units. Sedimentation significantly decreased the abundance of all eukaryotes except Arthropoda. Biological activated carbon (BAC) filtration and chlorine disinfection exerted strong effects on community composition. The eukaryotic communities in water were distinct from those in filter biofilms, as were the communities of different filter biofilms from each other. In contrast, communities were functionally similar among different filter biofilms, with the category metabolism being the dominant category represented, within which amino acid transport and metabolism (E) and energy production and conversion (C) dominated among subcategories. Seventy-one eukaryotic species pathogenic to humans were identified in raw water and filter biofilms. Quantitative PCR (qPCR) results showed that Acanthamoeba spp. and Vermamoeba vermiformis were present during some treatment processes, with concentrations of 12-1.2 × 105 copies/mL and 1 copy/mL, respectively. Neither of the two pathogenic amoebae was found in disinfected water. Canonical correspondence analysis (CCA) showed that pH was the most important environmental factor affecting eukaryotic community composition. Overall, the results provide insights into the eukaryotic community diversity in drinking water treatment plants and the potential eukaryotic hazards involved in drinking water production.

Investigation of the reaction mechanism and optical transparency in nanosecond laser welding of glasses assisted with titanium film.

The welding of glasses is widely used in many fields, such as optics, microfluidics, and microelectromechanical systems. In this paper, two pieces of 1 mm soda lime glass substrates were welded using a 1064 nm nanosecond laser assisted with a 14 nm titanium-coated thin film coating. Results show that after the laser irradiation, the welded area becomes highly transparent much like uncoated glass. The maximum change rate of transmittance of the welded zone is 8.88% in the wavelength range of 400-1800 nm, compared to a piece of 2 mm glass substrate. The chemical reaction process between the titanium film and the glass substrate of the highly transparent welded sample was analyzed by x-ray photoelectron spectroscopy. Welded quality and shear strength were characterized by scanning acoustic microscopy and shear tests.

Conservation tillage decreases selection pressure on community assembly in the rhizosphere of arbuscular mycorrhizal fungi.

Different tillage practices elicit various degrees of soil disturbance and significantly affect the community structure of soil microbes, especially rhizosphere microbes. However, little is known about the effects of tillage on community assembly and composition in the rhizosphere of arbuscular mycorrhizal fungi (RAMF). In this study, we investigated wheat RAMF communities under long-term different tillage patterns in an agroecosystem. The results showed that soil disturbance caused by tillage resulted in significant changes in RAMF communities, and this change varied with the degree of disturbance. Soil total nitrogen was the most relevant abiotic factor to RAMF communities. Notably, as a biotic selection factor, we found that cohesion of communities could also explain the changes in RAMF taxonomic and phylogenetic composition, which have not been revealed by other studies. Meanwhile, by analyzing the RAMF community assembly process under tillage practices, we found that stochastic processes dominated the assembly of RAMF communities under different tillage practices, and with the reduction of disturbance degree, the process occupied an increasingly important position. Overall, the structure and assembly process of the RAMF community in the rhizosphere varied with the degree of soil disturbance caused by tillage. These findings may provide more insights on underground processes and aid in the development of conservation tillage as a sustainable agricultural practice.

The Feasibility of Metagenomic Next-Generation Sequencing to Identify Pathogens Causing Tuberculous Meningitis in Cerebrospinal Fluid.

PURPOSE: The application of metagenomic next-generation sequencing (mNGS) in the diagnosis of tuberculous meningitis (TBM) remains poorly characterized. Here, we retrospectively analyzed data from patients with TBM who had taken both mNGS and conventional tests including culture of Mycobacterium tuberculosis (MTB), polymerase chain reaction (PCR) and acid-fast bacillus (AFB) stain, and the sensitivity and specificity of these methods were compared. METHODS: We retrospectively recruited TBM patients admitted to the hospital between December 2015 and October 2018. The first collection of cerebrospinal fluid (CSF) samples underwent both mNGS and conventional tests. In addition, patients with bacterial/cryptococcal meningitis or viral meningoencephalitis were mNGS positive controls, and a patient with auto-immune encephalitis was an mNGS negative control. RESULTS: Twenty three TBM patients were classified as 12 definite and 11 clinical diagnoses, which were based on clinical manifestations, pathogen evidence, CSF parameters, brain imaging, and treatment response. The mNGS method identified sequences of Mycobacterium tuberculosis complex (MBTC) from 18 samples (18/23, 78.26%). In patients with definite TBM, the sensitivity of mNGS, AFB, PCR, and culture to detect MTB in the first CSF samples were 66.67, 33.33, 25, and 8.33%, respectively. The specificity of each method was 100%. Among the four negative mNGS cases (4/23, 17.39%), three turned out positive by repeated AFB stain. The agreement of mNGS with the total of conventional methods was 44.44% (8/18). Combination of mNGS and conventional methods increased the detection rate to 95.65%. One patient was diagnosed as complex of TBM and cryptococcal meningitis, in which AFB stain and cryptococcal antigen enzyme immunoassay were positive and the DNA of Cryptococcus neoformans was detected by mNGS. CONCLUSION: Our study indicates that mNGS is an alternative method to detect the presence of mycobacterial DNA in CSF samples from patients with TBM and deserves to be applied as a front-line CSF test.

[Design of Intelligent Nursing Bed Based on Internet of Things + Technology].

With the advent of social aging, the development of intelligent multifunctional nursing beds that are suitable for hospitals, nursing homes, homes and the like has a wide range of applications, this paper presents an intelligent nursing bed design based on Internet of Things technology. The design uses STM32F103 as the central processor. The design is divided into nursing bed module based on tri-fold structure, central control module based on data processing, weight scale module based on weight detection, power supply module based on system power supply and host computer module based on user operation. The design uses a closed control mode, greatly improving the bed control accuracy. Experimental tests showed that under the action of the intelligent control bed control system, the error rate of bed position information driven bedboard can be less than 2%, which has high accuracy and stability.

Mechanisms for ·[Formula: see text] and ·OH Production on Flowerlike BiVO4 Photocatalysis Based on Electron Spin Resonance.

Many studies have focused on the use of BiVO4 as a photocatalyst, but few have investigated the production of free radicals during the photocatalytic process. Following synthesis of flowerlike BiVO4 and characterization by X-ray diffraction (XRD), Raman spectroscopy, Scanning electron microscopy (SEM) Scanning electron microscopy (EDX), UV-Vis and XPS, we successfully prepared BiVO4. Then we used electron spin resonance (ESR) to determine the production and degradation of individual active free radicals, including the superoxide radical (·[Formula: see text]) and the hydroxyl radical (·OH). In the first experiment, we used ESR to detect the signals of free radicals (·[Formula: see text] and ·OH) under varying oxygen conditions. The results shown that in addition to production by ·[Formula: see text], ·OH could also be produced by oxidation of h+ to OH-. In the next experiment, we detected ·OH under varying pH to identify the result of the first experiment, and found that signal intensities increased with increasing pH, indicating the mechanism for ·OH production. Finally, we conducted a trapping experiment to examine free radical degradation mechanisms. We identified ·OH and h+ as the main active free radicals and showed the complete production about ·OH. These results improve current knowledge of free radical production mechanisms, which can be used to enhance the photocatalytic performance of BiVO4.

Predictive power of abnormal electroencephalogram for post-cerebral infarction depression.

Electroencephalography is a sensitive indicator for measuring brain condition, and can reflect early changes in brain function and severity of cerebral ischemia. However, it is not yet known whether electroencephalography can predict development of post-cerebral infarction depression. A total of 321 patients with ischemic stroke underwent electroencephalography and Hamilton Depression Rating Scale assessment to analyze the relationship between electroencephalography and post-cerebral infarction depression. Our results show that electroencephalograms of ischemic stroke patients with depression exhibit low-amplitude alpha activity and slow theta activity. In contrast, electroencephalograms of ischemic stroke patients without depression show fast beta activity and slow delta activity. These findings confirm that low-amplitude alpha activity and slow theta activity can be considered as independent predictors for post-cerebral infarction depression.

Correlation between serum uric acid and diabetic peripheral neuropathy in T2DM patients.

AIM: To investigate the correlation between serum uric acid (SUA) and diabetic peripheral neuropathy (DPN) in type 2 diabetes mellitus (T2DM) patients. METHODS: Two hundred T2DM patients were divided into four groups at the cut-off points of 5, 7, and 9mg/dL of SUA levels. Nerve conduction studies (NCS), Semmes-Weinstein monofilament testing (SWMT), and vibration perception threshold (VPT) tests were performed on these patients. RESULTS: Significant differences in motor/sensory nerve amplitude and conduction velocity (CV) parameters among different SUA level groups were observed (all P<0.05). SUA levels were negatively correlated with the means of motor/sensory nerve amplitude and CV (all P<0.05). Duration of T2DM >10years, SUA >9mg/dL and total cholesterol (TC) >5.2mmol/L were found to be significantly associated with DPN (all P<0.05). Receiver-operating characteristic (ROC) analysis revealed that the cut-off points of T2DM duration combined with SUA and TC were 9years, 7.8mg/dL, and 4.97mmol/L, respectively (AUC=0.65; 95% CI: 0.53-0.77; sensitivity, 70.6%; specificity, 65.2%, P=0.009). CONCLUSION: There is a significant association between elevated SUA levels and DPN, and T2DM duration, SUA, and TC may be valuable indicators to predict the occurrence of DPN in T2DM patients.

Synthesis of Bi2S3/BiVO4 Heterojunction with a One-Step Hydrothermal Method Based on pH Control and the Evaluation of Visible-Light Photocatalytic Performance.

The band gaps of bismuth vanadate (BiVO4) and bismuth sulfide (Bi2S3) are about 2.40 eV and 1.30 eV, respectively. Although both BiVO4 and Bi2S3 are capable of strong visible light absorption, electron-hole recombination occurs easily. To solve this problem, we designed a one-step hydrothermal method for synthesizing a Bismuth sulfide (Bi2S3)/Bismuth vanadate (BiVO4) heterojunction using polyvinylpyrrolidone K-30 (PVP) as a structure-directing agent, and 2-Amino-3-mercaptopropanoic acid (l-cysteine) as a sulfur source. The pH of the reaction solution was regulated to yield different products: when the pH was 7.5, only monoclinic BiVO4 was produced (sample 7.5); when the pH was 8.0 or 8.5, both Bi2S3 and BiVO4 were produced (samples 8.0 and 8.5); and when the pH was 9.0, only Bi2S3 was produced (sample 9.0). In sample 8.0, Bi2S3 and BiVO4 were closely integrated with each other, with Bi2S3 particles formed on the surface of concentric BiVO4 layers, but the two compounds grew separately in a pH solution of 8.5. Visible-light photocatalytic degradation experiments demonstrated that the degradation efficiency of the Bi2S3/BiVO4 heterojunction was highest when prepared under a pH of 8.0. The initial rhodamine B in the solution (5 mg/L) was completely degraded within three hours. Recycling experiments verified the high stability of Bi2S3/BiVO4. The synthesis method proposed in this paper is expected to enable large-scale and practical use of Bi2S3/BiVO4.

Neurotropin® alleviates hippocampal neuron damage through a HIF-1α/MAPK pathway.

AIMS: The main purpose was to verify the potent capacity of Neurotropin® against neuronal damage in hippocampus and to explore its underlying mechanisms. METHODS: HT22 cells were treated with 40 µmol/L Aß25-35 in the presence of various concentrations of Neurotropin® or in its absence. The cell viability was assessed with a CCK-8 assay, and flow cytometry was used to measure cell apoptosis, intracellular ROS levels, and mitochondrial membrane potential. Aß plaques were examined by Bielschowsky silver staining, and the activities of antioxidants were detected in hippocampus of APP/PS1 mice after Neurotropin® treatment. The expression of proteins, including HIF-1α, Bcl-2, Bax, and MAPKs signaling molecules was evaluated by Western blot. RESULTS: Neurotropin® significantly reversed the cell injury induced by Aß25-35 through increasing cell viability and mitochondrial membrane potential, decreasing intracellular ROS and cell apoptosis of HT22 cells (P<.05). Furthermore, Neurotropin® markedly reduced the formation of Aß plaques and upregulated the activities of antioxidants (P<.05). Additionally, the protein expression of HIF-1α, p-ERK1/2, p-JNK, and p-P38 was significantly inhibited in hippocampus of APP/PS1 mice. CONCLUSIONS: Neurotropin® exhibited a potent neuroprotective effect on inhibiting Aß-induced oxidative damage and alleviating Aß deposition in hippocampus via modulation of HIF-1α/MAPK signaling pathway.