67 research outputs found

    Investigation on Titanium Silicalite‑1 Zeolite Synthesis Employing ATPAOH as an Organic Structure Directing Agent

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    Tetrapropylammonium hydroxide (TPAOH) as an organic structure directing agent (OSDA) is of great importance for the preparation of titanium silicalite-1 (TS-1) zeolite. In this paper, we employed a new OSDA, allyltripropylammonium hydroxide (ATPAOH), in the synthesis process and successfully synthesized ATS-1 zeolite (MFI type). Compared with traditional OSDA TPAOH, one of TPAOH’s propyl groups is substituted by an allyl group, which endows ATPAOH with unique properties. On the one hand, ATPAOH accelerates the crystallization rate of titanium silicalite zeolite remarkably due to the strong interaction between Ti species and ATPAOH during the crystallization period. On the other hand, ATPAOH is beneficial for the formation of isolated 6-coordinated Ti species, thus leading to the generation of lower amount of anatase. Owing to its abundant active Ti species, ATS-1 prepared by ATPAOH as OSDA exhibits a much better catalytic performance for the cyclohexanone ammoximation reaction than TS-1 prepared by TPAOH as OSDA

    Clinical application of Al18F-NOTA-FAPI PET/CT in diagnosis and TNM staging of pancreatic adenocarcinoma, compared to 18F-FDG

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    Abstract Purpose This study aimed to investigate the ability of Al18F-NOTA-FAPI PET/CT to diagnose pancreatic carcinoma and tumor-associated inflammation with the comparison of 18F-FDG PET/CT. Methods Prospective analysis of Al18F-NOTA-FAPI PET/CT and 18F-FDG PET/CT scans of 31 patients from 05/2021 to 05/2022 were analyzed. Al18F-NOTA-FAPI imaging was performed in patients who had Ce-CT and FDG PET/CT and the diagnosis was still unclear. Follow-up histopathology or radiographic examination confirmed the findings. Radiotracer uptake, diagnostic performance, and TNM (tumor-node-metastasis) classifications were compared. Results A total of 31 patients with pancreatic carcinoma (all were adenocarcinoma) underwent Al18F-NOTA-FAPI-04 PET/CT, including 20 male and 11 female patients, with a mean age of 58.2 ± 8.5 years. FAPI-04 PET/CT imaging showed a higher value of SUVmax-15min/30min/60min, SUVmean-15min/30min/60min, TBR1, and TBR2 in pancreatic carcinoma than FDG (all P < 0.01). The mean level of Al18F-NOTA FAPI-04 uptake values of the pancreatic ductal adenocarcinoma was higher than that of pancreatitis in both SUVmax-30min (P < 0.01), SUVmean-30min (P < 0.05), SUVmax-60min (P < 0.01), and SUVmean-60min (P < 0.01). The FAPI △SUVmax-1, △SUVmax-2, and △SUVmean-2 uptake values of pancreatic carcinoma were higher than tumor-associated inflammation (all P < 0.01). TNM staging of 16/31 patients changed after Al18F-NOTA FAPI-04 PET/CT examination with all upstaging changes. Conclusion Al18F-NOTA-FAPI-04 PET/CT at 15 and 30 min also demonstrated an equivalent detection ability of pancreatic lesion to 18F-FDG PET/CT. Delayed-phase Al18F-NOTA-FAPI-04 PET/CT can help differentiate pancreatic carcinoma and tumor-associated inflammation. Al18F-NOTA FAPI-04 PET/CT also performed better than FDG PET/CT in TNM staging. Trial registration Chinese Clinical Trial Registry, ChiCTR2100051406. Registered 23 September 2021, https://www.chictr.org.cn/showproj.html?proj=13303

    Recognition of Unsafe Onboard Mooring and Unmooring Operation Behavior Based on Improved YOLO-v4 Algorithm

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    In the maritime industry, unsafe behaviors exhibited by crew members are a significant factor contributing to shipping and occupational accidents. Among these behaviors, unsafe operation of mooring lines is particularly prone to causing severe accidents. Video-based monitoring has been demonstrated as an effective means of detecting these unsafe behaviors in real time and providing early warning to crew members. To this end, this paper presents a dataset comprising videos of unsafe mooring line operations by crew members on the M.V. YuKun. Additionally, we propose an unsafe behavior recognition model based on the improved You Only Look Once (YOLO)-v4 network. Experimental results indicate that the proposed model, when compared to other models such as the original YOLO-v4 and YOLO-v3, demonstrates a significant improvement in recognition speed by approximately 35% while maintaining accuracy. Additionally, it also results in a reduction in computation burden. Furthermore, the proposed model was successfully applied to an actual ship test, which further verifies its effectiveness in recognizing unsafe mooring operation behaviors. Results of the actual ship test highlight that the proposed model’s recognition accuracy is on par with that of the original YOLO-v4 network but shows an improvement in processing speed by 50% and a reduction in processing complexity by about 96%. Hence, this work demonstrates that the proposed dataset and improved YOLO-v4 network can effectively detect unsafe mooring operation behaviors and potentially enhance the safety of marine operations.</p

    Metal Ti quantum chain-inlaid 2D NaSn2(PO4)3/H-doped hard carbon hybrid electrodes with ultrahigh energy storage density

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    We report the development of a new hybrid electrode that allows for a reinforcing combination of different energy storage mechanisms, providing enhanced energy and power densities. This hybrid electrode is composed of chain-like metal titanium (zero valency state) quantum dots (<10 nm), two-dimension NaSn2(PO4)3 layer and H-doped hard carbon layer, and possesses unique sandwich and hierarchically meso-macroporous structures. These chain-like quantum dots are inlaid on the edge of ultra-thin NaSn2(PO4)3 nanosheets by using a convenient and economic method, enhancing its conductivity. This design takes advantage of the unique properties of each component and nanostructure, resulting in synergistic effects to improve the charge transfer and energy storage. The hybrid electrode not only shows high capacity, outstanding rate performance and long cycling stability, but also matches well with porous Na3V2(PO4)3 cathode. Remarkably, the Na/Li mixed-ion full battery exhibits significant improvements on the energy and power densities (555 Wh Kg-1/804 W Kg-1 at 1C). Detailed charge storage mechanism investigation reveals that the prelithiation reduces the pseudocapacitive of hybrid electrode and increases its battery behavior, resulting in an ultrahigh energy storage density. Our findings demonstrate that this hybrid electrode is a new potential candidate for high-performance mixed-ion batteries

    Confined van der Waals Epitaxial Growth of Two-Dimensional Large Single-Crystal In2Se3 for Flexible Broadband Photodetectors

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    The controllable growth of two-dimensional (2D) semiconductors with large domain sizes and high quality is much needed in order to reduce the detrimental effect of grain boundaries on device performance but has proven to be challenging. Here, we analyze the precursor concentration on the substrate surface which significantly influences nucleation density in a vapor deposition growth process and design a confined micro-reactor to grow 2D In2Se3 with large domain sizes and high quality. The uniqueness of this confined micro-reactor is that its size is ~102-103 times smaller than that of a conventional reactor. Such a remarkably small reactor causes a very low precursor concentration on the substrate surface, which reduces nucleation density and leads to the growth of 2D In2Se3 grains with sizes larger than 200 μm. Our experimental results show large domain sizes of the 2D In2Se3 with high crystallinity. The flexible broadband photodetectors based on the as-grown In2Se3 show rise and decay times of 140 ms and 25 ms, efficient response (5.6 A/W), excellent detectivity (7×1010 Jones), high external quantum efficiency (251%), good flexibility, and high stability. This study, in principle, provides an effective strategy for the controllable growth of high quality 2D materials with few grain boundaries

    Research on an Auto-Optimized Capacitor Voltage Balancing Control Strategy of MMC SM for Renewable Energy HVDC Transmission System

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    The Modular Multilevel Converter (MMC) is one of the most attractive converter topologies in the High Voltage Direct Current (HVDC) transmission field. The latest widely used sorting method has a low algorithm complexity. It can effectively balance the sub-module (SM) capacitor voltages, but it would cause relatively high switching frequency and power loss. Aiming at the problem that the sub-module (SM) capacitor voltage sorting algorithm has a large switching loss due to the high switching frequency of the device, this paper proposes an auto-optimized capacitor voltage balancing control strategy. Firstly, the topology and operation principle of MMC are analyzed. Secondly, a SM capacitor voltage control method based on the dynamic deviation threshold is proposed. Considering the switch switching state of the SM and the difference between the voltages of each SM, the algorithm can obtain the dynamic deviation valve using the closed-loop control. The method can avoid the unnecessary repeated switching of the Insulated Gate Bipolar Transistor (IGBT) under the premise of ensuring that the capacitance voltages of the SMs are basically the same, which effectively result in reducing the switching frequency of the MMC SM and reducing the switching loss, thereby improving the operating efficiency of the system. Finally aiming at the proposed control strategy, the simulation and experimental verification are carried out which shows that the proposed algorithm can better control the system voltage deviation, reduce the switching loss of the system and improve the stability of the system

    Genomic variants in an inbred mouse model predict mania-like behaviors.

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    Contemporary rodent models for bipolar disorders split the bipolar spectrum into complimentary behavioral endophenotypes representing mania and depression. Widely accepted mania models typically utilize single gene transgenics or pharmacological manipulations, but inbred rodent strains show great potential as mania models. Their acceptance is often limited by the lack of genotypic data needed to establish construct validity. In this study, we used a unique strategy to inexpensively explore and confirm population allele differences in naturally occurring candidate variants in a manic rodent strain, the Madison (MSN) mouse strain. Variants were identified using whole exome resequencing on a small population of animals. Interesting candidate variants were confirmed in a larger population with genotyping. We enriched these results with observations of locomotor behavior from a previous study. Resequencing identified 447 structural variants that are mostly fixed in the MSN strain relative to control strains. After filtering and annotation, we found 11 non-synonymous MSN variants that we believe alter protein function. The allele frequencies for 6 of these variants were consistent with explanatory variants for the Madison strain's phenotype. The variants are in the Npas2, Cp, Polr3c, Smarca4, Trpv1, and Slc5a7 genes, and many of these genes' products are in pathways implicated in human bipolar disorders. Variants in Smarca4 and Polr3c together explained over 40% of the variance in locomotor behavior in the Hsd:ICR founder strain. These results enhance the MSN strain's construct validity and implicate altered nucleosome structure and transcriptional regulation as a chief molecular system underpinning behavior

    Molecular Imaging for the Prediction of Chemotherapeutic Sensitivity in Human Breast Cancer Xenograft

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    The aim of the present study was to investigate the possible use of mouse double-minute 2 ( MDM2 ) molecular imaging to predict chemotherapeutic sensitivity in breast cancer xenografts (BCXs). MCF-7 cells were transfected with MDM2 antisense oligonucleotides (ASONs), and MDM2 expression levels were determined by Western blotting. Cell viability was assessed by 3-(4,5- dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay in MCF-7 cells transfected with ASONs and treated with paclitaxel. BCXs were established in nude mice by injection of ASONs, and tumor volumes were measured after paclitaxel treatment. MDM2 ASONs were labeled with 99m Tc to generate an MDM2 molecular probe, and MDM2 expression levels were evaluated by imaging and Western blotting. MDM2 ASONs downregulated MDM2 expression in a dose-dependent manner and increased the rate of paclitaxel-induced cell growth inhibition. Imaging of tumors revealed significant differences in the tumor to skeletal muscle (T/M) ratio between groups. Tumor MDM2 protein expression was correlated with T/M ratios at 4 hours ( R = .880) and 10 hours ( R = .886). The effect of paclitaxel varied among nude mice bearing BCXs with different concentrations of ASONs, as shown by differences in tumor growth. MDM2 molecular imaging could be a promising method for predicting the sensitivity of BCXs to chemotherapy

    Endogenous CNS expression of neurotensin and neurotensin receptors is altered during the postpartum period in outbred mice.

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    Neurotensin (NT) is a neuropeptide identical in mice and humans that is produced and released in many CNS regions associated with maternal behavior. NT has been linked to aspects of maternal care and previous studies have indirectly suggested that endogenous NT signaling is altered in the postpartum period. In the present study, we directly examine whether NT and its receptors exhibit altered gene expression in maternal relative to virgin outbred mice using real time quantitative PCR (qPCR) across multiple brain regions. We also examine NT protein levels using anti-NT antibodies and immunohistochemistry in specific brain regions. In the medial preoptic area (MPOA), which is critical for maternal behaviors, mRNA of NT and NT receptor 3 (Sort1) were significantly up-regulated in postpartum mice compared to virgins. NT mRNA was also elevated in postpartum females in the bed nucleus of the stria terminalis dorsal. However, in the lateral septum, NT mRNA was down-regulated in postpartum females. In the paraventricular nucleus of the hypothalamus (PVN), Ntsr1 expression was down-regulated in postpartum females. Neurotensin receptor 2 (Ntsr2) expression was not altered in any brain region tested. In terms of protein expression, NT immunohistochemistry results indicated that NT labeling was elevated in the postpartum brain in the MPOA, lateral hypothalamus, and two subregions of PVN. Together, these findings indicate that endogenous changes occur in NT and its receptors across multiple brain regions, and these likely support the emergence of some maternal behaviors
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