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Multi-resistant Staphylococcus aureus (S. aureus) infection is a significant global health concern owing to its high mortality and morbidity rates. Coagulase (Coa), a key enzyme that activates prothrombin to initiate host coagulation, has emerged as a promising target for anti-infective therapeutic approaches. This study identified sinigrin as a potent Coa inhibitor that significantly inhibited S. aureus-induced coagulation at concentration as low as 32 mg/L. Additionally, at a higher concentration of 128 mg/L, sinigrin disrupted the self-protection mechanism of S. aureus. Thermal shift and fluorescence-quenching assays confirmed the direct binding of sinigrin to the Coa protein. Molecular docking analysis predicted specific binding sites for sinigrin in the Coa molecule, and point mutation experiments highlighted the importance of Arg-187 and Asp-222 as critical binding sites for both Coa and sinigrin. In vivo studies demonstrated that the combination of sinigrin with oxacillin exhibited greater antibacterial efficacy than oxacillin alone in the treatment of S. aureus-induced pneumonia in mice. Furthermore, sinigrin was shown to reduce bacterial counts and inflammatory cytokine levels in the lung tissues of S. aureus-infected mice. In summary, sinigrin was shown to directly target Coa, resulting in the attenuation of S. aureus virulence, which suggests the potential of sinigrin as an adjuvant for future antimicrobial therapies.
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Surface plasmon resonance (SPR) is widely used in photonic crystal fiber sensors. In this work, a photonic crystal fiber sensor based on HE1,1 mode excited SPR is designed and analyzed by the finite element method. The maximum wavelength sensitivity, optimal resolution, and amplitude sensitivity of the optical fiber sensor are 24,600 nm/RIU, 4.07×10-6RIU, and 1164.13RIU-1, respectively, for the refractive index range between 1.29 and 1.39. The sensor has excellent properties and wide application prospects in bimolecular and biochemical sensing, environmental monitoring, food safety, and other fields.
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Óptica e Fotônica , Ressonância de Plasmônio de Superfície , Refratometria , Fibras Ópticas , FótonsRESUMO
Microstructured polarization beam splitters (PBSs) have attracted much interest in recent years. Here, a ring double-core photonic crystal fiber (PCB) PSB (PCB-PSB) with an ultrashort, broadband, and high extinction ratio (ER) was designed. The effects of the structural parameters on the properties were analyzed by the finite element method, which revealed that the optimal length of the PSB was 19.08877 µm and the ER was -324.257d B. The operating bandwidth for an ER of less than -20d B is 440 nm, and the wavelength range spans the full E+S+C+L+U band between 1,320 and 1,760 nm. The fault and manufacturing tolerance of the PBS was demonstrated for structural errors of ±1%. Moreover, the influence of temperature on the performance of the PBS was determined and discussed. Our results show that a PBS has excellent potential in optical fiber sensing and optical fiber communications.
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Staphylococcus aureus (S. aureus) induces a variety of infectious diseases in humans and animals and is responsible for hospital- and community-acquired infections. The aim of this study was to investigate how bilobetin, a natural compound, attenuates S. aureus virulence by inhibiting two key virulence factors, von Willebrand factor-binding protein (vWbp) and staphylocoagulase (Coa). The results showed that bilobetin inhibited Coa- or vWbp-induced coagulation without affecting S. aureus proliferation. The Western blotting and fluorescence quenching assays indicated that bilobetin did not affect the expression of vWbp and Coa but directly bound to the proteins with KA values of 1.66 × 104 L/mol and 1.04 × 104 L/mol, respectively. To gain further insight into the mechanism of interaction of bilobetin with these virulence factors, we performed molecular docking and point mutation assays, which indicated that the TYR-6 and TYR-18 residues on vWbp and the ALA-190 and ASP-189 residues on Coa were essential for the binding of bilobetin. In addition, the in vivo studies showed that bilobetin ameliorated lung tissue damage and inflammation caused by S. aureus, thereby improving the survival of mice. Furthermore, the use of bilobetin as an adjuvant in combination with vancomycin was more effective in the treatment of a mouse model of pneumonia. Taken together, bilobetin had a dual inhibitory effect on vWbp and Coa by reducing the virulence of S. aureus, suggesting that it is a viable lead compound against S. aureus infections.
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Coagulase , Infecções Estafilocócicas , Humanos , Camundongos , Animais , Coagulase/genética , Coagulase/metabolismo , Coagulase/farmacologia , Proteínas de Transporte/metabolismo , Staphylococcus aureus , Virulência , Fator de von Willebrand/metabolismo , Fator de von Willebrand/farmacologia , Simulação de Acoplamento Molecular , Infecções Estafilocócicas/tratamento farmacológico , Fatores de Virulência/genética , Fatores de Virulência/metabolismoRESUMO
In mobile edge computing (MEC), mobile devices can choose to offload their tasks to edge servers for execution, thereby effectively reducing the completion time of tasks and energy consumption of mobile devices. However, most of the data transfer brought by offloading relies on wireless communication technology, making the private information of mobile devices vulnerable to eavesdropping and monitoring. Privacy leakage, especially the location and association privacies, can pose a significant risk to users of mobile devices. Therefore, protecting the privacy of mobile devices during task offloading is important and cannot be ignored. This paper considers both location privacy and association privacy of mobile devices during task offloading in MEC and targets to reduce the leakage of location and association privacy while minimizing the average completion time of tasks. To achieve these goals, we design a privacy-preserving task offloading scheme to protect location privacy and association privacy. The scheme is mainly divided into two parts. First, we adopt a proxy forwarding mechanism to protect the location privacy of mobile devices from being leaked. Second, we select the proxy server and edge server for each task that needs to be offloaded. In the proxy server selection policy, we make a choice based on the location information of proxy servers, to reduce the leakage risk of location privacy. In the edge server selection strategy, we consider the privacy conflict between tasks, the computing ability, and location of edge servers, to reduce the leakage risk of association privacy plus the average completion time of tasks as much as possible. Simulated experimental results demonstrate that our scheme is effective in protecting the location privacy and association privacy of mobile devices and reducing the average completion time of tasks compared with the-state-of-art techniques.
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Comunicação , Privacidade , Computadores de Mão , Tecnologia da Informação , PolíticasRESUMO
A high-sensitivity surface plasmon resonance (SPR) sensor is designed and analyzed numerically. The sensor is constructed on the eightfold U-shaped photonic quasi-crystal fiber (PQF) and coated with indium tin oxide (ITO). The coupling between the core mode and surface plasmon polariton mode is enhanced due to shortening of the distance between the core and the ITO layer, so that the PQF-SPR sensor exhibits high refractive index (RI) sensitivity in the near-infrared region. The maximum wavelength sensitivity and the corresponding resolution of this sensor are 42,000 nm/RIU and 2.38×10-6RIU, respectively. The average wavelength sensitivity is 12,750 nm/RIU in the refractive index range of 1.306-1.386. This advanced sensor is suitable for the determination of RIs in the near-infrared region.
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We propose and experimentally demonstrate an accurate modulation-format-indepen-dent and cascaded filtering effect (CFE) insensitive in-band optical signal-to-noise ratio (OSNR) monitoring technique enabled by Gaussian process regression (GPR) utilizing a widely tunable optical bandpass filter (OBPF) and optical power measurements. By adjusting the center frequency of a widely tunable OBPF and measuring the corresponding output optical power as the input features of GPR, the proposed OSNR monitoring technique is experimentally proven to be transparent to modulation formats and robust to CFE, chromatic dispersion (CD), polarization mode dispersion (PMD), and nonlinear effect (NLE). Experimental results for 9-channel 32Gbaud PDM-16QAM signals with 50GHz channel spacing demonstrate OSNR monitoring with the root mean squared error (RMSE) of 0.429 dB and the mean absolute error (MAE) of 0.294 dB, in the OSNR range of -1â¼30 dB. Even better, our proposed technique has the potential to be employed for link monitoring at the intermediation nodes and can eliminate the necessity to know the transmission information.
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Circular RNAs were recently identified as a novel type of noncoding RNAs. An increasing number of reports have demonstrated their essential regulatory roles in various biological processes and human diseases, including cancer. However, the role of circRNA in cervical cancer (CC) remains largely unknown. In the current study, we investigated the physiological functions of circ_0067934 during CC development and progression. We found that circ_0067934 was overexpressed in CC tissues and cell lines. Circ_0067934 upregulation was associated with advanced stage, lymph node metastasis, and poor prognosis in CC patients. Knockdown of circ_0067934 suppressed the proliferation, colony formation, migration, invasion, and epithelial-mesenchymal transition of CC cells in vitro. Circ_0067934 loss also inhibited CC tumor growth in vivo. Mechanistically, silencing circ_0067934 increased miR-545 expression. MiR-545 repressed EIF3C expression through targeting its 3'-untranslated region. MiR-545 suppressed the proliferation, migration, and invasion of CC cells, whereas restoration of EIF3C could rescue the effects of circ_0067934 knockdown. Taken together, our findings revealed that circ_0067934 promotes CC progression via miR-545/EIF3C axis. Our study may provide a new insight into the pathogenesis of CC.
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Progressão da Doença , Fator de Iniciação 3 em Eucariotos/metabolismo , MicroRNAs/metabolismo , Oncogenes , RNA Circular/metabolismo , Neoplasias do Colo do Útero/genética , Neoplasias do Colo do Útero/patologia , Animais , Sequência de Bases , Linhagem Celular Tumoral , Movimento Celular/genética , Proliferação de Células/genética , Transição Epitelial-Mesenquimal/genética , Fator de Iniciação 3 em Eucariotos/genética , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Camundongos Endogâmicos BALB C , Camundongos Nus , MicroRNAs/genética , Invasividade Neoplásica , RNA Circular/genética , Regulação para Cima/genéticaRESUMO
H-type hypertension, which is a specific form of hypertension characterized by elevated plasma homocysteine (Hcy) levels, has become a major public health challenge worldwide. This study investigated the hypotensive effects and underlying mechanisms of Huotan Jiedu Tongluo decoction (HTJDTLD), a highly effective traditional Chinese medicine formula commonly used to treat vascular stenosis. Methionine was used to induce H-type hypertension in rats, and HTJDTLD was administered intragastrically. Then, the systolic and diastolic blood pressures of the caudal artery of rats were measured by noninvasive rat caudal manometry. Histological assessment of the aorta was performed by hematoxylin-eosin (HE) staining. Enzyme-linked immunosorbent assay (ELISA) was used to measure Hcy levels, and quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) and western blotting were used to determine the mRNA and protein levels of Glucose regulatory protein 78 (GRP78), Tumor necrosis factor (TNF) receptor-associated factor 2 (TRAF2), c-Jun N-terminal kinases (JNK), and caspase-3. The results showed that HTJDTLD significantly lowered blood pressure, alleviated histopathological lesions, and decreased Hcy levels after methionine treatment. Moreover, HTJDTLD significantly inhibited the gene and protein expression of GRP78, JNK, TRAF2, and caspase 3, which are involved mainly in the endoplasmic reticulum (ER) stress-induced apoptosis pathway. Overall, the results indicated that HTJDTLD had effective antihypertensive effects in rats with H-type hypertension and revealed the antihypertensive mechanisms associated with inhibition of ER stress-induced apoptosis pathway activation.
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Anti-Hipertensivos , Medicamentos de Ervas Chinesas , Hipertensão , Animais , Medicamentos de Ervas Chinesas/farmacologia , Ratos , Hipertensão/tratamento farmacológico , Hipertensão/metabolismo , Anti-Hipertensivos/farmacologia , Masculino , Ratos Sprague-Dawley , Homocisteína/sangueRESUMO
Background: Individuals who initiate the concealment of their adverse or distressing thoughts from others can trigger off negative psychological experiences and social isolation, and lead to poorer health. Therefore, this study aimed to analyze the psychometric properties of the Self-Concealment Scale (SCS) in Chinese older adults. Methods: A questionnaire was administered to 1085 elderly people using convenience sampling and snowball sampling. Scales used included the SCS, Distress Disclosure Index (DDI), Revised Cheek and Buss Shyness Scale (RCBS), Social Interaction Anxiety Scale (SIAS), Social Phobia Scale (SPS), UCLA Loneliness Scale (ULS-8), and Kessler Psychological Distress Scale (K10). Results: The SCS consisted of 10 items with a one-dimensional structure, explaining 55.66% of the variance. The factor loading values for each item ranged from 0.68 to 0.75, and the covariance ranged from 0.46 to 0.57. Confirmatory factor analysis showed good model fit (χ2/df=2.829, RMSEA=0.057, CFI=0.981, IFI=0.981, TLI=0.974, PNFI=0.712, PGFI=0.719). The criterion-related validity test found that the SCS was significantly and positively correlated with the RCBS, SIAS, SPS, ULS-8, K10, depression, and anxiety; and the SCS was significantly and negatively correlated with the DDI. The Cronbach's α coefficient value for the scale was 0.923; the split-half reliability coefficient value was 0.923. In addition, the SCS had cross-gender consistency. Conclusion: The SCS has good reliability and validity in older adults and can be used as a valid tool to assess self-concealment among older people.
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Antimicrobial resistance (AMR) is a global health threat. The dramatic increase of Methicillin-resistant Staphylococcus aureus (MRSA) infections emphasizes the need to find new anti-infective agents with a novel mode of action. The Caseinolytic protease (ClpP) is a central virulence factor in stress survival, virulence, and antibiotic resistance of MRSA. Here, we found ayanin, a flavonoid isolated from Callicarpa nudiflora, was an inhibitor of MRSA ClpP with an IC50 of 19.63 µM. Using quantitative real-time PCR, ayanin reduced the virulence of Staphylococcus aureus (S. aureus) by down-regulating the level of some important virulence factors, including agrA, RNAâ ¢, hla, pvl, psmα and spa. The results of cellular thermal shift assay and thermal shift assay revealed a binding between ayanin and ClpP. Molecular docking showed that ASP-168, ASN-173 and ARG-171 were the potential binding sites for ClpP binding to ayanin. ClpP mutagenesis study further indicated that ARG-171 and ASN-173 were the main active sites of ClpP. The affinity constant (KD) value of ayanin with ClpP was 3.15 × 10-5 M measured by surface plasmon resonance. In addition, ayanin exhibited a significant therapeutic effect on pneumonia infection induced by S. aureus in mice in vivo, especially in combination with vancomycin. This is the first report of ayanin with in vivo and in vitro efficacy against S. aureus infection. In conclusion, ayanin is a promising therapeutic agent to combat MRSA infections by targeting ClpP.
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Staphylococcus aureus Resistente à Meticilina , Infecções Estafilocócicas , Animais , Camundongos , Staphylococcus aureus , Peptídeo Hidrolases/farmacologia , Simulação de Acoplamento Molecular , Flavonoides/farmacologia , Flavonoides/uso terapêutico , Infecções Estafilocócicas/tratamento farmacológico , Fatores de Virulência , Endopeptidases , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Testes de Sensibilidade MicrobianaRESUMO
Aim: Our primary objective was to investigate the protective effects and mechanisms of isovanillic acid in mice infected with Staphylococcus aureus Newman. Methods: In vitro coagulation assays were used to validate vWbp and Coa as inhibitory targets of isovanillic acid. The binding mechanism of isovanillic acid to vWbp and Coa was investigated using molecular docking and point mutagenesis. Importantly, a lethal pneumonia mouse model was used to assess the effect of isovanillic acid on survival and pathological injury in mice. Results & Conclusion: Isovanillic acid reduced the virulence of S. aureus by directly binding to inhibit the clotting activity of vWbp and Coa, thereby reducing lung histopathological damage and improving the survival rate in mice with pneumonia.
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Coagulase , Infecções Estafilocócicas , Camundongos , Animais , Coagulase/metabolismo , Staphylococcus aureus/metabolismo , Simulação de Acoplamento Molecular , Infecções Estafilocócicas/prevenção & controleRESUMO
Background: Given the high incidence and high mortality of cervical cancer (CC) among women in developing countries, identifying reliable biomarkers for the prediction of prognosis and therapeutic response is crucial. We constructed a prognostic signature of cuproptosis-related long non-coding RNAs (lncRNAs) as a reference for individualized clinical treatment. Methods: A total of seven cuproptosis-related lncRNAs closely related to the prognosis of patients with CC were identified and used to construct a prognostic signature via least absolute shrinkage and selection operator regression analysis in the training set. The predictive performance of the signature was evaluated by Kaplan-Meier (K-M) analysis, receiver operating characteristic (ROC) analysis, and univariate and multivariate Cox analyses. Functional enrichment analysis and single-sample gene set enrichment analysis were conducted to explore the potential mechanisms of the prognostic signature, and a lncRNA-microRNA-mRNA network was created to investigate the underlying regulatory relationships between lncRNAs and cuproptosis in CC. The associations between the prognostic signature and response to immunotherapy and targeted therapy were also assessed. Finally, the prognostic value of the signature was validated using the CC tissues with clinical information in my own center. Results: A prognostic signature was developed based on seven cuproptosis-related lncRNAs, including five protective factors (AL441992.1, LINC01305, AL354833.2, CNNM3-DT, and SCAT2) and two risk factors (AL354733.3 and AC009902.2). The ROC curves confirmed the superior predictive performance of the signature compared with conventional clinicopathological characteristics in CC. The ion transport-related molecular function and various immune-related biological processes differed significantly between the two risk groups according to functional enrichment analysis. Furthermore, we discovered that individuals in the high-risk group were more likely to respond to immunotherapy and targeted therapies including trametinib and cetuximab than those in the low-risk group. Finally, CC tissues with clinical data from my own center further verify the robustness of the seven-lncRNA risk signature. Conclusion: We generated a cuproptosis-related lncRNA risk signature that could be used to predict prognosis of CC patients. Moreover, the signature could be used to predict response to immunotherapy and chemotherapy and thus could assist clinicians in making personalized treatment plans for CC patients.
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OBJECTIVE: To elucidate the effects of the deleted in colorectal carcinoma (DCC) gene on proliferation of ovarian cancer cell line SKOV-3. METHOD: An exogenous recombinant eukaryotic expression vector pcDNA3.1(+)-DCC, containing human DCC cDNA coding sequences, was constructed and transfected into SKOV-3 cells (SKOV-3/DCC). The pcDNA3.1 (+) transfected cells (SKOV-3/Neo) and SKOV-3 cells were used as the positive and negative controls, respectively. Expressions of DCC mRNA and protein were analyzed by RT-PCR and immunocytochemical analysis, respectively. Cell growth was detected by soft agar colony formation assay and MTT assay. Flow cytometry and transmission electron microscopy were used to assess the effects of DCC on cell cycle distribution and ultrastructure, respectively. BALB/c mice were used to evaluate the effects of DCC on tumorigenicity in vivo. RESULTS: RT-PCR and immunocytochemical analysis revealed the exogenous DCC gene was successfully transfected into SKOV-3 cell lines and obtained permanent expression. The half maximal inhibitory concentration (IC50) of SKOV-3/DCC cells was significantly lower than that of SKOV-3 or SKOV-3/Neo cells (all P<0.05). DCC expression caused SKOV-3 cells to be arrested in G1 phase (78.0%), and electron microscopic analysis showed SKOV-3/DCC cells displayed typical morphological changes of apoptosis. Two mice xenografted with SKOV-3/DCC cells showed no tumor tumorigenecity. The tumor volume of BALB/c mice bearing SKOV-3/DCC cells (3.403 mm(3)) was smaller than that of SKOV-3 cells (9.206 mm(3)). CONCLUSION: DCC gene may play an important role in suppressing the growth of SKOV-3 cell line and inducing apoptosis.
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Neoplasias Ovarianas/terapia , Receptores de Superfície Celular/metabolismo , Proteínas Supressoras de Tumor/metabolismo , Animais , Apoptose/genética , Apoptose/fisiologia , Ciclo Celular/genética , Ciclo Celular/fisiologia , Linhagem Celular Tumoral , Proliferação de Células , Receptor DCC , Feminino , Humanos , Imuno-Histoquímica , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Microscopia Eletrônica de Transmissão , Neoplasias Ovarianas/genética , Neoplasias Ovarianas/metabolismo , Receptores de Superfície Celular/genética , Transfecção , Proteínas Supressoras de Tumor/genética , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
OBJECTIVE: To observe the alteration of QT dispersion (QTd) and QTc dispersion (QTcd) in hemodialysis patients after oral administration of Zhigancao Decoction (, Roasted Licorice Decoction, RLD). METHODS: To investigate the alteration of QTd and QTcd in 68 routine hemodialysis patients before and after hemodialysis with 12-lead electrocardiogram (ECG) after orally administrated RLD for 4 weeks. Blood was also taken for measurement of plasma electrolytes, liver function, renal function, hemoglobin (Hgb) and hematocrit (HCT). RESULTS: After hemodialysis, QTd and QTcd were prolonged evidently; the difference was significant between before and after hemodialysis (P<0.05). After RLD orally administrated for 4 weeks, QTd and QTcd only slightly increased after dialysis compared with pre-dialysis (P>0.05). The QTd and QTcd of the post-therapy-post-dialysis decreased significantly compared with the pre-therapy-post-dialysis (P<0.05). There were no other significant changes in other variables (post-therapy-pre-dialysis vs. pre-therapy-pre-dialysis, or post-therapy-post-dialysis vs. pre-therapy-post-dialysis;P>0.05). After therapy, the number of patients with supraventricular arrhythmia, occasional ventricular premature beat and multiple ventricular premature beat were decreased from 15 to 4, 10 to 2 and 7 to 1, respectively. CONCLUSION: RLD therapy not only lowered the increased QTd and QTcd after hemodialysis, but also displayed a safety profile.
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Medicamentos de Ervas Chinesas/administração & dosagem , Medicamentos de Ervas Chinesas/uso terapêutico , Eletrocardiografia , Diálise Renal , Adulto , Idoso , Demografia , Feminino , Humanos , Falência Renal Crônica/tratamento farmacológico , Falência Renal Crônica/fisiopatologia , Masculino , Pessoa de Meia-IdadeRESUMO
Digital images are now widely used in modern clinic diagnosis. The diagnostic images with confidential information related to patients' privacy are stored and transmitted via public networks. Secured schemes to guarantee confidentiality of patients' privacy are becoming more and more vital. This paper proposes an adaptive medical image encryption algorithm based on improved chaotic mapping in order to overcome the defects of the existing chaotic image encryption algorithm. First, the algorithm used Logistic-sine chaos mapping to scramble the plain image. Then, the scrambled image was divided into 2-by-2 sub blocks. By using the hyper-chaotic system, the sub blocks were adaptively encrypted until all the sub block encryption was completed. By analyzing the key space, the information entropy, the correlation coefficient and the plaintext sensitivity of the algorithm, experimental results show that the proposed algorithm overcomes the shortcoming of lack of diffusion in single direction encryption. It could effectively resist all kinds of attacks and has better security and robustness.
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In2O3 nanoparticles hybrid twins hexagonal disk (THD) ZnO with different ratios were fabricated by a hydrothermal method. The as-obtained ZnO/In2O3 composites are constituted by hexagonal disks ZnO with diameters of about 1 µm and In2O3 nanoparticles with sizes of about 20-50 nm. With the increase of In2O3 content in ZnO/In2O3 composites, the absorption band edges of samples shifted from UV to visible light region. Compared with pure ZnO, the ZnO/In2O3 composites show enhanced photocatalytic activities for degradation of methyl orange (MO) and 4-nitrophenol (4-NP) under solar light irradiation. Due to suitable alignment of their energy band-gap structure of the In2O3 and ZnO, the formation of type п heterostructure can enhance efficient separation of photo-generate electro-hole pairs and provides convenient carrier transfer paths.
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BACKGROUND: This study aimed to investigate the effects of silk fiber (SF)/calcium phosphate cement (CPC) biocomposite on repairing radial bone defects in rabbits. METHODS: Four-month-old New Zealand rabbits were selected to create a bilateral radial bone defect model and divided into four groups according to implanted material: SF/CPC, SF/CPC/particulate bone (PB), PB, and control (C). The specimens were removed at four and eight postoperative weeks for general observation, X-ray examination, tissue slicing, scanning electron microscopy (SEM), and biomechanical testing. RESULTS: Postoperative X-ray showed no bone defect repair in group C and different degrees of bone defect repair in the other three groups. Imaging, histology, and SEM showed the following: group SF/CPC formed fine trabecular bone in week 4, while the maximum bending load in group SF/CPC in week 4 was significantly different from those in the other groups (P < 0.05). CONCLUSIONS: SF/CPC has good biocompatibility and bone-inducing ability, demonstrating its bone defect-repairing ability.
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Cimentos Ósseos/química , Substitutos Ósseos/química , Fosfatos de Cálcio , Rádio (Anatomia)/cirurgia , Seda , Animais , Fenômenos Biomecânicos , Teste de Materiais/métodos , Microscopia Eletrônica de Varredura/métodos , Coelhos , Radiografia , Rádio (Anatomia)/diagnóstico por imagem , Rádio (Anatomia)/ultraestrutura , Engenharia Tecidual/métodos , CicatrizaçãoRESUMO
Porous- and hollow-structured LiNb3O8 anode material was prepared by a hydrothermal-assisted sintering strategy for the first time. The phase evolution was studied, and the formation mechanism of the porous and hollow structure was proposed. The formation of the unique structure can be attributed to the local existence of liquid phase because of the volatilization of Li element. As the anode material, the initial discharge capacity is 285.1 mAhg-1 at 0.1 C, the largest discharge capacity reported so far for LiNb3O8. Even after 50 cycles, the reversible capacity can still maintain 77.6 mAhg-1 at 0.1 C, about 2.5 times of that of LiNb3O8 samples prepared by traditional solid-state methods. The significant improvement of Li storage capacity can be attributed to the special porous and hollow structure, which provides a high density of active sites and short parallel channels for fast intercalation of Li+ ions through the surface.
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The effects of Li/Nb ratio on the preparation of Li-Nb-O compounds by a hydrothermal method were studied deeply. Li/Nb ratio has a great impact on the formation of LiNbO3; the ratio smaller than 3:1 is beneficial to the formation of LiNbO3, while larger than 3:1, forms no LiNbO3 at all and the morphology and chemical bond of Nb2O5 raw material are totally modified by Li ions. The reason can be attributed to the large content of LiOH, which is beneficial to form Li3NbO4 not LiNbO3, and also, even if LiNbO3 particle locally forms, it is easily dissolved in LiOH solution with strong alkalinity. Pure LiNb3O8 powders are obtained with two absolutely opposite Li/Nb ratios: 8:1 and 1:3; the former shows a unique porous and hollow structure, quite different from the particle aggregation (the latter shows). Compared with Li/Nb = 1:3, the 4.2 times higher photocatalytic performance of LiNb3O8 (Li/Nb = 8:1) are observed and it can be attributed to the unique porous and hollow structure, which provides a high density of active sites for the degradation of MB. Compared to LiNbO3, the improved photocatalytic performance of LiNb3O8 can be attributed to its layered structure type with the reduced symmetry enhancing the separation of electrons and holes.