Unraveling the Structure-Activity-Stability Relationship over Gallium-Promoted HZSM-5 Nanocrystalline Aggregates for Propane Aromatization.

The aromatization of light alkane is an important process for increasing the aromatic production and utilization efficiency of light alkane resources simultaneously. Herein, Ga-modified HZSM-5 catalysts were prepared and investigated by a series of characterization techniques such as X-ray diffraction, nuclear magnetic resonance spectroscopy, transmission electron microscopy, N2 adsorption-desorption, and NH3 temperature-programmed desorption to study their physicochemical properties. The catalytic performance in propane aromatization was also tested. Importantly, the structure-activity relationship, reaction pathway, and coke formation mechanism in propane aromatization were systematically explored. It was found that different Ga introduction methods would affect the amounts of Brønsted and Lewis acid sites, and Ga-HZSM-5 prepared by the hydrothermal method exhibited higher amounts of Brønsted and Lewis acid sites but a lower B/L ratio. As a result, Ga-HZSM-5 showed higher propane conversion and benzene, toluene, and xylene yield compared with that of Ga2O3/HZSM-5. The propane aromatization reaction pathway indicated that propane dehydrogenation to propene was a crucial step for aromatic formation. The increase of the Lewis acid density in Ga-HZSM-5 can effectively improve the dehydrogenation rate and promote the aromatization reaction. Furthermore, the formation of coke species was studied by thermogravimetry-mass spectrometry and Raman approaches, the results of which indicated that the graphitization degree of coke formed over spent Ga-HZSM-5 is lower, resulting in enhanced anticoking stability.

Insidious transmission of Mycobacterium tuberculosis in Ordos, China: a molecular epidemiology study.

BACKGROUND: In this study, we conducted this population-based study to evaluate the genetic diversity and clustering rate of Mycobacterium tuberculosis (MTB) strains using the whole-genome sequencing (WGS), to better understand its transmission in Ordos. METHODS: All patients with culture-positive TB notified in Ordos from January 2021 to December 2022 were recruited. WGS was performed to analyze single-nucleotide polymorphism (SNP) and to identify genotypic drug susceptibilities of MTB isolates. RESULTS: Overall, a total of 186 patients were included in the present study, of whom 35 (18.8%) had no symptoms suggestive of active TB. Lineage 2 was the predominant MTB sublineage, accounting for 186 of isolates tested. When the pairwise SNP difference ≤ 12 was used as the cutoff for WGS-based clusters, we identified 17 genotypic clusters, and 38 isolates belonged to these 17 clusters, resulting in a clustering rate of 20.4%. The Beijing genotype was an independent factor associating with genomic-clustering (adjusted OR 4.219, 95% CI 0.962-18.502). The overall sensitivity on WGS-based resistance prediction was 85.7% for rifampicin, 73.1% for isoniazid, 60.0% for Ethambutol, 72.7% for streptomycin, and 72.7% for fluoroquinolones. CONCLUSION: To conclude, the present study demonstrates the extensive recent transmission of Beijing genotype strains in the community of Ordos. The failure to provide a comprehensive pattern of transmission indicated the missed diagnosis of active TB within the community. A substantial proportion of subclinical TB cases are recognized in the bacteria-positive cases, emphasizing that we must interrupt transmission by finding people with active TB before they infect others.

YOLOv4 with Deformable-Embedding-Transformer Feature Extractor for Exact Object Detection in Aerial Imagery.

The deep learning method for natural-image object detection tasks has made tremendous progress in recent decades. However, due to multiscale targets, complex backgrounds, and high-scale small targets, methods from the field of natural images frequently fail to produce satisfactory results when applied to aerial images. To address these problems, we proposed the DET-YOLO enhancement based on YOLOv4. Initially, we employed a vision transformer to acquire highly effective global information extraction capabilities. In the transformer, we proposed deformable embedding instead of linear embedding and a full convolution feedforward network (FCFN) instead of a feedforward network in order to reduce the feature loss caused by cutting in the embedding process and improve the spatial feature extraction capability. Second, for improved multiscale feature fusion in the neck, we employed a depth direction separable deformable pyramid module (DSDP) rather than a feature pyramid network. Experiments on the DOTA, RSOD, and UCAS-AOD datasets demonstrated that our method's average accuracy (mAP) values reached 0.728, 0.952, and 0.945, respectively, which were comparable to the existing state-of-the-art methods.

Microstructure and Mechanical Properties of Y4Zr3O12-Added Fe-13.5Cr-2W Oxide-Dispersion-Strengthened Steels, Containing High Contents of C and N, Prepared by Mechanical Alloying and Two-Step Spark Plasma Sintering.

Oxide-dispersion-strengthened (ODS) steel is considered as a promising candidate structural material for nuclear applications. In this study, the microstructure and mechanical properties of Y4Zr3O12-added Fe-13.5Cr-2W ODS steels, containing high contents of C and N, prepared by mechanical alloying (MA) and two-step spark plasma sintering (SPS), were investigated. The results showed that pure Y4Zr3O12 powders, with a grain size of 3.5 nm, were well prepared with NH3·H2O addition by the sol-gel method in advance, in order to avoid the formation of some coarse or undesired oxides. W was completely dissolved into the matrix after 48 h of ball milling at 300 rpm, and the main elements were uniformly distributed on the surface of the milled powders. The unexpected face-centered cubic (FCC, γ)/body-centered cubic (BCC, α) dual-phase structure of the sintered specimens, could be explained by the unexpectedly high contents of C and N from the raw powder production process, fast-sintering characteristic of SPS, and inhibitory effect of W on the diffusion of C. The experimental results were approximately consistent with the simulation results from the Thermo Calc software. The temperature combination of 800 °C and 1100 °C during the SPS process, provided a relatively more homogeneous microstructure, while the combination of 750 °C and 1150 °C, provided the highest ultimate tensile strength (UTS), of 1038 MPa, with the highest uniform elongation (UE), of 6.2%. M23C6, Cr2O3, M2(C,N), and other precipitates, were mainly distributed at grain boundaries, especially at the triple junctions, which led to Cr depletion at grain boundaries.

Selectivity mechanism of GRK2/5 inhibition through in silico investigation.

As two representative isoforms of G protein-coupled receptor kinases family, the largest known membrane receptor family, GRK2 and GRK5 are ubiquitously distributed in human heart, brain, lung, kidney, skeletal muscle and other tissues. GRK2 and GRK5 have common functions implicated in the regulation of heart failure, though GRK5 has also been involved in diseases like hypertension, cancer, diabetes and Alzheimer's disease. Therefore, to clarify the selectivity mechanism towards GRK2 and GRK5 will be of great significance for the discovery of effective and selective inhibitors. To this end, the structures and chemical properties of key residues were analyzed among GRK2 and GRK5 derived from their respective protein crystal structures. Furthermore, a combination of multiple computational strategies, including sequence superposition, receptor-ligand docking, molecular dynamics, MM-GBSA calculation, QM/MM approach and pharmacological modeling, were integrated to validated and elucidate their unique binding modes towards highly selective inhibitors. In addition, the specific amino acid distribution within the GRK2/5 target site is also analyzed in this paper, which can guide future research and development of selective inhibitors in a more targeted manner. Overall, our study comprehensively clarifies the selectivity mechanism of GRK2/5 inhibition, thereby providing guidance for further rational design of selective inhibitors targeting GRK2/5.

A Reconfigurable Differential-to-Single-Ended Autonomous Current Adaptation Buffer Amplifier Suitable for Biomedical Applications.

A reconfigurable differential-to-single-ended autonomous current adaptation buffer amplifier (ACABA) is proposed. The ACABA, based on floating-gate technologies, is a capacitive circuit, of which output DC level and bandwidth can be adjusted by programming charges on floating nodes. The gain is variable by switching different amounts of capacitors without altering the output DC level. Without extra sensing and control circuitries, the current consumption of the proposed ACABA increases spontaneously when the input signal is fast or large, achieving a high slew rate. The supply current dwindles back to the low quiescent level autonomously when the output voltage reaches equilibrium. Therefore, the proposed ACABA is power-efficient and suitable for processing physiological signals. A prototype ACABA has been designed and fabricated in a [Formula: see text] CMOS process occupying an area of [Formula: see text]. When loaded by a [Formula: see text] capacitor, it consumes [Formula: see text] to achieve a unity-gain bandwidth of [Formula: see text] with a measured IIP2 value of [Formula: see text] and a slew rate of [Formula: see text].

Cross-linked γ-cyclodextrin metal-organic framework-a new stationary phase for the separations of benzene series and polycyclic aromatic hydrocarbons.

The cross-linked γ-cyclodextrin metal-organic framework (CL-CD-MOF) was synthesized by crosslinking γ-cyclodextrin metal-organic framework (γ-CD-MOF) with diphenyl carbonate to separate benzene series and polycyclic aromatic hydrocarbons (PAHs). The separation ability of the CL-CD-MOF packed column was assessed in both reverse-phase (RP-) and normal-phase (NP-) modes. The retention mechanisms of these compounds were discussed and confirmed by combining molecular simulations in detail. It was found that baseline separation could be obtained in RP-HPLC mode and it was superior to commercial C18 column in separating xylene isomers. The interaction between CL-CD-MOF and analytes, such as dipole-dipole interaction, π-electron transfer interaction, hydrophobic interaction, and van der Waals force, may dominate the chromatographic separation, and CL-CD-MOF column had a certain shape recognition ability. In addition, the composition of the mobile phase also had a crucial effect. Moreover, the column demonstrated satisfactory stability and repeatability (the relative standard deviations of retention time, peak height, peak area, and half peak width for six replicate separations of the tested analytes were within the ranges 0.17-1.1%, 0.96-1.9%, 0.23-1.7%, and 0.32-1.9%, respectively) and there was no significant change in the separation efficiency for at least 3 years of use. Thermodynamic characteristics indicated that the process of separations on the CL-CD-MOF column was both negative enthalpy change (ΔH) and entropy change (ΔS) controlled. The excellent performance made CL-CD-MOF a promising HPLC stationary phase material for separation and determination of benzene series and PAHs.

Design of an arbitrary ratio optical power splitter based on a discrete differential multiobjective evolutionary algorithm.

Traditional photonic integrated devices are designed to predict their optical response by transforming the structure and parameters, and it is often difficult to obtain devices with excellent performance in all aspects. The nanophotonic computing design method based on the optimization algorithm has revolutionized the traditional photonic integrated device design technology. Here, we report a discrete differential evolution algorithm that simulates a natural selection process to achieve an ultracompact arbitrary power ratio splitter. The footprint of the designed splitter is only ${2.5}\;\unicode{x00B5} {\rm m} \times {2}.{5}\;\unicode{x00B5} {\rm m}$2.5µm×2.5µm, the simulated total transmission efficiency is above 90%, the power ratio error is less than 3%, and it can work normally over the C-band. Our algorithm can provide new ideas for the application of genetic algorithms to the automatic optimization of photonic integrated devices.

Refined pharmacophore features for virtual screening of human thromboxane A2 receptor antagonists.

For a long time, the structural basis of TXA2 receptor is limited due to the lack of crystal structure information, till the release of the crystal structure of TXA2 receptor, which deepens our understanding about ligand recognition and selectivity mechanisms of this physiologically important receptor. In this research, we report the successful implementation in the discovery of an optimal pharmacophore model of human TXA2 receptor antagonists through virtual screening. Structure-based pharmacophore models were generated based on two crystal structures of human TXA2 receptor (PDB entry 6IIU and 6IIV). Docking simulation revealed interaction modes of the virtual screening hits against TXA2 receptor, which was validated through molecular dynamics simulation and binding free energy calculation. ADMET properties were also analyzed to evaluate the toxicity and physio-chemical characteristics of the hits. The research would provide valuable insight into the binding mechanisms of TXA2 receptor antagonists and thus be helpful for designing novel antagonists.

Compact polarization beam splitter assisted by subwavelength grating in triple-waveguide directional coupler.

A polarization beam splitter (PBS) is one of the key components for manipulating different polarization states in the areas of optical interconnection and communication. In this paper, a PBS with two coupling regions using a subwavelength grating (SWG) waveguide as a bridge is proposed and investigated on a 340-nm silicon-on-insulator platform. The PBS is designed with a triple-waveguide directional coupler consisting of two identical silicon waveguides and an SWG waveguide sandwiched between them. The tailorable dispersion relation of the SWG waveguide offers a flexible design freedom. With the optimized grating period and duty ratio, the input TE mode will experience efficient coupling between the silicon waveguide and the SWG waveguide, while the TM mode can directly pass through without influence. The results show that with a device length of 6.5 µm, the extinction ratios and insertion losses of the two modes are higher than 27 dB and lower than 0.3 dB at a wavelength of 1550 nm, respectively.

Sensitivity Enhancement in Surface Plasmon Resonance Biochemical Sensor Based on Transition Metal Dichalcogenides/Graphene Heterostructure.

In this work, a surface plasmon resonance (SPR) biosensor based on two-dimensional transition metal dichalcogenides (TMDCs) is proposed to improve the biosensor’s sensitivity. In this sensor, different kinds of two-dimensional TMDCs are coated on both surfaces of metal film. By optimizing the structural parameters, the angular sensitivity can reach as high as 315.5 Deg/RIU with 7-layers WS2 and 36 nm Al thin film, which is 3.3 times of the conventional structure based on single Al thin film. We also obtain maximum phase sensitivity (3.85 × 106 Deg/RIU) with bilayer WS2 and 35 nm Al thin film. The phase sensitivity can be further improved by employing Ag and removing air layer. The proposed configuration is of great potential for biochemical sensing.