320 research outputs found

    Stiffness improvement methods and its application on design and optimization of large lens hood for space camera

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    As an essential part of optical system, lens hoods consisting of shells and plates are designed mainly to protect optical system from unexpected light. Except for such basic function, the hood proposed in this paper has to load several subassemblies and will be applied in high-resolution and wild field-of-view space camera with strict mass limitation, which makes effective mechanical reinforcement and lightweight of hood quite necessary. To meet such requirements, stiffness improvement methods is promoted in this paper to help improve the constraint fundamental frequency and decide the areas where subassemblies can be placed. Subsequently, optimization on key sizes of the hood proceeds to achieve a higher fundamental frequency and a lower weight. Finally, a prototype is fabricated based on the optimal design and a sweep test is held to verify the analytical fundamental frequency. The prototype has large external dimensions (1960×1640×2055 mm) but weighs only 33.5 kg when loading several subassemblies which totally weight 15.95 kg. Sweep test indicates that experimental constraint fundamental frequency is 36.82 Hz. All the parameters coincide with that of theoretical design well. The whole work of this paper provides a worthwhile method to the design of lens hood with large external dimensions and high specific stiffness in space camera. Since the lens hood is a typical plate and shell structure, the method, design and optimization process in this paper may also be helpful to the plate and shell structure in which stiffness and lightweight are highly required

    Inhibition of autophagy promotes sonodynamic therapy-induced apoptosis of pancreatic cancer cells

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    Introduction. Sonodynamic therapy (SDT), a promising non-invasive therapeutic modality, has attracted increasing attention in the treatment of pancreatic cancer (PC). At present, the role of autophagy in SDT of PC remains unclear. This study aims to explore the role of autophagy in SDT of PC and its effect on apoptosis of PC cells. Material and methods. PC cells (Capan-1 and BxPC-3) underwent incubation with 5-aminolevulinic acid (5-ALA) or/and ultrasound (US) exposure (control, 5-ALA, US, and SDT groups), followed by measurement of cell apoptosis and autophagy. Specifically, cell viability, apoptosis, and the expression of apoptosis-related proteins (cleaved Caspase-3, Bax, and Bcl-2) were measured using CCK-8 assay, flow cytometry, and western blot analysis, respectively. The mitochondrial morphology was observed with the transmission electron microscopy, accompanied by the detection of autophagosome marker (LC3) co-located with Mito and the protein expression of LC3II/I. Before SDT treatment, the autophagy inhibitor 3-MA and the apoptosis inhibitor z-VAD were respectively added to PC cell cultures to evaluate the effects of autophagy inhibition on apoptosis and apoptosis inhibition on autophagy in PC cells. Results. Compared with the control group, cell viability was inhibited and cell apoptosis and autophagy were enhanced in the SDT group, while cell viability, autophagy, and apoptosis in the 5-ALA and US groups were not significantly changed. Moreover, 3-MA treatment inhibited autophagy and accelerated apoptosis, whereas z-VAD treatment reduced apoptosis but did not affect autophagy in PC cells. Conclusions. Autophagy was activated in SDT-treated PC cells, and inhibition of autophagy promoted cell apoptosis in PC cells

    Observation of integer and fractional quantum anomalous Hall states in twisted bilayer MoTe2

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    The interplay between strong correlations and topology can lead to the emergence of intriguing quantum states of matter. One well-known example is the fractional quantum Hall effect, where exotic electron fluids with fractionally charged excitations form in partially filled Landau levels. The emergence of topological moir\'e flat bands provides exciting opportunities to realize the lattice analogs of both the integer and fractional quantum Hall states without the need for an external magnetic field. These states are known as the integer and fractional quantum anomalous Hall (IQAH and FQAH) states. Here, we present direct transport evidence of the existence of both IQAH and FQAH states in twisted bilayer MoTe2 (AA stacked). At zero magnetic field, we observe well-quantized Hall resistance of h/e2 around moir\'e filling factor {\nu} = -1 (corresponding to one hole per moir\'e unit cell), and nearly-quantized Hall resistance of 3h/2e2 around {\nu} = -2/3, respectively. Concomitantly, the longitudinal resistance exhibits distinct minima around {\nu} = -1 and -2/3. The application of an electric field induces topological quantum phase transition from the IQAH state to a charge transfer insulator at {\nu} = -1, and from the FQAH state to a generalized Wigner crystal state, further transitioning to a metallic state at {\nu} = -2/3. Our study paves the way for the investigation of fractionally charged excitations and anyonic statistics at zero magnetic field based on semiconductor moir\'e materials

    Research Progress in Components, Structure and Functions of Human Milk and Bovine Milk Fat Globules

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    As an important nutrient in milk, fat exists in the form of milk fat globules. Cow’s milk is an important substitute for breast milk, but the difference between its milk fat globules and those of human milk remains to be clarified. In this paper, the main differences in protein composition, lipid composition, structure and function between cow’s and human milk fat globules are reviewed. The types of milk fat globule membrane proteins (MFGMPs) in human milk are significantly more than those in cow’s milk, and there are also obvious differences in the abundance of some special proteins. The composition and distribution of unsaturated and saturated fatty acids in cow’s milk and human milk are also different. Sphingomyelin is more abundant in human milk phospholipids, but in cow’s milk, lecithin is the main phospholipid. In all mammalian milk, the core of the lipid structure is triglyceride, encapsulated by a complex three-layer membrane. In terms of composition and structure, there is heterogeneity in milk fat globule membrane (MFGM) between the same species and different species. By summarizing the differences between human milk and cow’s milk fat globules, this review aims to increase the utilization rate and value of milk MFGM, to improve the structure of simulated milk fat globules, and to further optimize infant formula

    Correlation and predictive ability of sensory characteristics and social interaction in children with autism spectrum disorder

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    BackgroundIndividuals with autism spectrum disorder (ASD) often have different social characteristics and particular sensory processing patterns, and these sensory behaviors may affect their social functioning. The objective of our study is to investigate the sensory profiles of children with ASD and their association with social behavior. Specifically, we aim to identify the predictive role of sensory processing in social functioning.MethodsThe Short Sensory Profile (SSP) was utilized to analyze sensory differences between ASD children and their peers. The Social Responsiveness Scale (SRS) and other clinical scales were employed to assess the social functioning of children with ASD. Additionally, the predictive ability of sensory perception on social performance was discussed using random forest and support vector machine (SVM) models.ResultsThe SSP scores of ASD children were lower than those of the control group, and there was a significant negative correlation between SSP scores and clinical scale scores (P < 0.05). The random forest and SVM models, using all the features, showed higher sensitivity, while the random forest model with 7-feature factors had the highest specificity. The area under the receiver operating characteristic (ROC) curve (AUC) for all the models was higher than 0.8.ConclusionAutistic children in our study have different patterns of sensory processing than their peers, which are significantly related to their patterns of social functioning. Sensory features can serve as a good predictor of social functioning in individuals with ASD

    Confinement of carbon dots localizing to the ultrathin layered double hydroxides toward simultaneous triple-mode bioimaging and photothermal therapy

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    It is a great challenge to develop multifunctional nanocarriers for cancer diagnosis and therapy. Herein, versatile CDs/ICG-uLDHs nanovehicles for triple-modal fluorescence/photoacoustic/two-photon bioimaging and effective photothermal therapy were prepared via a facile self-assembly of red emission carbon dots (CDs), indocyanine green (ICG) with the ultrathin layered double hydroxides (uLDHs). Due to the J-aggregates of ICG constructed in the self-assembly process, CDs/ICG-uLDHs was able to stabilize the photothermal agent ICG and enhanced its photothermal efficiency. Furthermore, the unique confinement effect of uLDHs has extended the fluorescence lifetime of CDs in favor of bioimaging. Considering the excellent in vitro and in vivo phototherapeutics and multimodal imaging effects, this work provides a promising platform for the construction of multifunctional theranostic nanocarrier system for the cancer treatment

    Relationship between sheep feces scores and gastrointestinal microorganisms and their effects on growth traits and blood indicators

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    Fecal scores are crucial for assessing the digestive and gastrointestinal status of animals. The Bristol fecal scoring system is a commonly used method for the subjective evaluation of host feces, there is limited research on fecal scoring standards for fattening Hu sheep. In this study, Hu sheep were collected for rumen, rectum, and colon contents for 16S rDNA sequencing. 514 Hu sheep feces were scored based on the Bristol fecal scoring system, and production performance at each stage was measured. Finally, we developed the scoring standard of the manure of Hu sheep in the fattening period (a total of five grades). The result shows that moisture content significantly increased with higher grades (p < 0.05). We analyzed the relationship between fecal scores and production traits, blood indices, muscle nutrients, and digestive tract microorganisms. The growth traits (body weight, body height, body length, average daily gain (ADG), and average daily feed intake (ADFI) during 80–180 days), body composition traits of the F3 group, and the carcass traits were found to be significantly higher (p < 0.05) than those of the F1 and F2 groups. There was no significant difference in gastrointestinal microflora diversity among all groups (p > 0.05). Significant differences were observed in Aspartate aminotransferase, Glucose, Total bilirubin, and Red Blood Cell Count between groups (p < 0.05). The mutton moisture content in group F4 was significantly higher than in the other groups, and the protein content was also the lowest (p < 0.05). The results of the correlation analysis demonstrated that Actinobacteria, Peptostreptococcaceae, Acidaminococcales, Gammaproteobacteria, and Proteobacteria were the significant bacteria affecting fecal scores. In addition, Muribaculaceae and Oscillospiraceae were identified as the noteworthy flora affecting growth performance and immunity. This study highlights the differences in production traits and blood indicators between fecal assessment groups and the complex relationship between intestinal microbiota and fecal characteristics in Hu sheep, suggesting potential impacts on animal performance and health, which suggest strategies for improved management
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