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Low molecular water-soluble chitosan was prepared by the depolymerization of chitosan in the presence of a series of catalysts with active W(O2) sites. Both the peroxo species [W2O3(O2)4]2- and {PO4[WO(O2)2]4}3- showed high efficiency in the degradation of chitosan, indicating that the degradation mechanism did not follow the radical mechanism. That means •OH is not the active species, which has been proven by the fluorescence spectra. H2O2 acted as an oxidant to regenerate the active W(O2) sites in the depolymerization of chitosan. The developed catalyst (TBA)3{PO4[WO(O2)2]4} is recoverable.

This paper studied the atomization characteristics of different spray nozzles under the spot spraying method and designed a test system for the atomization characteristics. First, the effective spray height range was determined based on the effective droplet size of 106–403 μm, the spray height of 200–500 mm, the operating speed of 0.5–1 m/s, and the droplet size requirements. The effective height ranges of the HVV25-02, HVV40-02, and HVV50-02 nozzles are 277–500 mm, 200–426 mm, and 200–266 mm, respectively. Second, the influences of pressure, the opening time of the solenoid valve, and the nozzle aperture on the atomization characteristics were studied through experiment. The experiment was repeated three times, with 10,000 points monitored each time. The test results show that the droplet size of spot spraying decreases with the increase in pressure, while the droplet velocity and droplet distribution relative span have no correlation with pressure. With the increase in the opening time of the solenoid valve, the droplet size does not change regularly, the droplet velocity generally shows an upward trend, and the droplet distribution relative span (RS) value decreases gradually. With the increase in the nozzle aperture, both droplet size and droplet velocity increase, and the distribution span shows a trend of first increasing and then decreasing. The droplet velocity of spot spraying is 4.1 m/s lower than that of continuous spraying, on average, and the droplet distribution relative span value is 2.2 higher than that of continuous spraying. This research can provide a basis and reference for the selection of appropriate spot spraying operation parameters.

Graphitic carbon nitrides were employed to prepare the Ruthenium-based ammonia synthesis catalysts by thermal decomposition of Ru 3 (CO) 12 under N 2 or H 2 atmosphere. Different pretreatment atmospheres significantly affected the interaction between Ru nanoparticles and the graphitic carbon nitride. The strong metal support interaction enhanced the electronic density transfer from rich-electron π-plane of the support to the Ru nanoparticles. And it further caused the upshift of d-band center of Ru nanoparticles. The upshift of d-band center improved the ability of surface to bond to N 2 , and consequently the ammonia synthesis activity was enhanced. Graphical Abstract Electron-rich and graphitic carbon nitride enhanced the electron density of Ru nanoparticles. And that caused the upshift of d-band center of Ru nanoparticles. This upshift of d-band center improved the ability of surface to bond to N 2 , and consequently the ammonia synthesis activity was enhanced.

In order to study the thermal stability of coated carbonyl iron powder (CIP) and its influence on magnetic properties, carbonyl iron powder was coated with a silica layer and then annealed in an air atmosphere at elevated temperatures. Transmission electron microscopy (TEM) analysis and Fourier transform infrared spectroscopy confirmed the existence of a silicon dioxide layer with a thickness of approximately 80~100 nm. Compared with uncoated CIP, the silicon-coated CIP still maintained a higher absorption performance after annealing, and the calculated impedance matching value Z only slightly decreased. It is worth noting that when the annealing temperature reached 300 °C, coercivity (Hc) increased, and the real and imaginary parts of the permeability decreased, which means that the silicon dioxide layer began to lose its effectiveness. On the contrary, the significant decrease in microwave absorption ability and impedance matching value Z of uncoated CIP after annealing were mainly because the newly formed oxide on the interface became the active polarization center, leading to an abnormal increase in permittivity. In terms of the incremental mass ratio after annealing, 2% was a tipping point for permeability reduction.

SnZn(OH)6 (ZHS) with different morphologies were synthesized by a facile self-templated method at room temperature. It was found that the morphology of ZHS could be controlled by varying the concentration of OH−. The crystalline structure and morphology of the particles were characterized by x-ray diffraction, UV-vis diffuse reflectance spectroscopy, scanning electron microscopy images, and N2 adsorption. The results indicated that the particles had almost uniform monoclinic geometry and uniform size. The photocatalytic activity of ZHS with different morphologies was tested through degradation of Rhodamine B (RhB). Therein, the hollow ZHS showed the highest light catalytic performance due to its large BET surface area, wide band gap, and high crystallinity.

SnZn(OH)6 (ZHS) with different morphologies were synthesized by a facile self-templated method at room temperature. It was found that the morphology of ZHS could be controlled by varying the concentration of OH super(-). The crystalline structure and morphology of the particles were characterized by x-ray diffraction, UV-vis diffuse reflectance spectroscopy, scanning electron microscopy images, and N2 adsorption. The results indicated that the particles had almost uniform monoclinic geometry and uniform size. The photocatalytic activity of ZHS with different morphologies was tested through degradation of Rhodamine B (RhB). Therein, the hollow ZHS showed the highest light catalytic performance due to its large BET surface area, wide band gap, and high crystallinity.

Multiple linear stapler firings is a risk factor for anastomotic leakage (AL) in laparoscopic low anterior resection (LAR) using double stapling technique (DST) anastomosis. In this study, our objective was to establish the risk factors for ≥ 3 linear stapler firings, and to create and validate a predictive model for ≥ 3 linear stapler firings in laparoscopic LAR using DST anastomosis. We retrospectively enrolled 328 mid–low rectal cancer patients undergoing laparoscopic LAR using DST anastomosis. With a split ratio of 4:1, patients were randomly divided into 2 sets: the training set (n = 260) and the testing set (n = 68). A clinical predictive model of ≥ 3 linear stapler firings was constructed by binary logistic regression. Based on three-dimensional convolutional networks, we built an image model using only magnetic resonance (MR) images segmented by Mask region-based convolutional neural network, and an integrated model based on both MR images and clinical variables. Area under the curve (AUC), sensitivity, specificity, accuracy, positive predictive value (PPV), and Youden index were calculated for each model. And the three models were validated by an independent cohort of 128 patients. There were 17.7% (58/328) patients received ≥ 3 linear stapler firings. Tumor size ≥ 5 cm (odds ratio (OR) = 2.54, 95% confidence interval (CI) = 1.15–5.60, p = 0.021) and preoperative carcinoma embryonic antigen (CEA) level > 5 ng/mL [OR = 2.20, 95% CI = 1.20–4.04, p = 0.011] were independent risk factors associated with ≥ 3 linear stapler firings. The integrated model (AUC = 0.88, accuracy = 94.1%) performed better on predicting ≥ 3 linear stapler firings than the clinical model (AUC = 0.72, accuracy = 86.7%) and the image model (AUC = 0.81, accuracy = 91.2%). Similarly, in the validation set, the integrated model (AUC = 0.84, accuracy = 93.8%) performed better than the clinical model (AUC = 0.65, accuracy = 65.6%) and the image model (AUC = 0.75, accuracy = 92.1%). Our deep-learning model based on pelvic MR can help predict the high-risk population with ≥ 3 linear stapler firings in laparoscopic LAR using DST anastomosis. This model might assist in determining preoperatively the anastomotic technique for mid–low rectal cancer patients.

Marangoni spreading on thin films is widely observed in nature and applied in industry. It has serious implications for airway drug delivery, especially in surfactant displacement therapy. This paper reports the results of experimental investigations of a surfactant-laden droplet spreading on films made of more viscous Newtonian fluids as well as on films made of viscoelastic fluids. The experiments used particle seeding, the transmission-speckle method and particle tracking velocimetry (PTV) to determine the deformation of the film–droplet interface and to measure velocity fields. Radially aligned patterns were observed on Newtonian films. Similar patterns, but with much smaller wavenumber, were observed on viscoelastic films in combination with rapid azimuthal variations of the film thickness. The Saffman–Taylor instability at the film–droplet interface explains the formation of patterns on a more viscous Newtonian film, and their onset requires exceeding the critical capillary number. The pattern formation on viscoelastic films is correlated with an instability at the film–droplet–air contact line when the liquid is expelled radially by the spreading droplet. PTV revealed azimuthal variations of the velocity field in the vicinity of the contact line. The observed contact line instability is different from previously reported fingering instabilities of Newtonian thin films. A simple scaling law accounting for the Marangoni-stress-induced elastic shear deformation is proposed to describe the flow field in the patterns formed in the viscoelastic films.

CRISPR-Cas systems revolutionize life science. Metagenomes contain millions of unknown Cas proteins. Traditional mining relies on protein sequence alignments. In this work, we employ an evolutionary scale language model (ESM) to learn the information beyond sequences. Trained with CRISPR-Cas data, ESM accurately identifies Cas proteins without alignment. Limited experimental data restricts feature prediction, but integrating with machine learning enables trans -cleavage activity prediction of uncharacterized Cas12a. We discover 7 undocumented Cas12a subtypes with unique CRISPR loci. Structural analyses reveal 8 subtypes of Cas1, Cas2, and Cas4. Cas12a subtypes display distinct 3D-folds. CryoEM analyses unveil unique RNA interactions with the uncharacterized Cas12a. These proteins show distinct double-strand and single-strand DNA cleavage preferences and broad PAM recognition. Finally, we establish a specific detection strategy for the oncogene SNP without traditional Cas12a PAM. This study highlights the potential of language models in exploring undocumented Cas protein function via gene cluster classification. Novel Cas protein discovery is vital in CRISPR-Cas technology. Here, authors develop AIL-Scan, an AI-assisted Cas detection strategy using the ESM model, and discover seven unreported Cas12a subtypes with distinct DNA cleavage and PAM recognition, enabling SNP detection and precise gene editing.

COVID-19 remains a persistent threat, especially with the predominant Omicron variant emerging in early 2022, presenting with high transmissibility, immune escape, and waning. There is a need to rapidly ramp up global vaccine coverage while enhancing public health and social measures. Timely and reliable estimation of the reproduction number throughout a pandemic is critical for assessing the impact of mitigation efforts and the potential need to adjust for control measures. We conducted a systematic review on the reproduction numbers of the Omicron variant and gave the pooled estimates. We identified six studies by searching PubMed, Embase, Web of Science, and Google Scholar for articles published between 1 January 2020 and 6 March 2022. We estimate that the effective reproduction number ranges from 2.43 to 5.11, with a pooled estimate of 4.20 (95% CI: 2.05, 6.35). The Omicron variant has an effective reproduction number which is triple (2.71 (95% CI: 1.86, 3.56)) that of the Delta variant.