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1.
Opt Express ; 30(10): 16794-16801, 2022 May 09.
Artículo en Inglés | MEDLINE | ID: mdl-36221514

RESUMEN

Room-temperature polariton lasing is achieved in GaN microrods grown by metal-organic vapor phase epitaxy. We demonstrate a large Rabi splitting (Ω = 2g0) up to 162 meV, exceeding the results from both the state-of-the-art nitride-based planar microcavities and previously reported GaN microrods. An ultra-low threshold of 1.8 kW/cm2 is observed by power-dependent photoluminescence spectra, with the linewidth down to 1.31 meV and the blue shift up to 17.8 meV. This large Rabi splitting distinguishes our coherent light emission from a conventional photon lasing, which strongly supports the preparation of coherent light sources in integrated optical circuits and the study of exciting phenomena in macroscopic quantum states.

2.
Opt Express ; 29(24): 39788-39800, 2021 Nov 22.
Artículo en Inglés | MEDLINE | ID: mdl-34809335

RESUMEN

We investigate the exciton polaritons and their corresponding optical modes in a hexagonal GaN microrod at room temperature. The dispersion curves are measured by the angle-resolved micro-photoluminescence spectrometer, and two types of exciton polaritons are identified with the help of the finite-difference time-domain simulation. By changing the pump position, the photon part of the exciton polaritons is found to switch between the quasi-whispering gallery modes and the two-round quasi-whispering gallery modes. The exciton polaritons formed by the latter are observed and distinguished for the first time, with a giant Rabi splitting as large as 2Ω = 230.3 meV.

3.
Int J Neurosci ; 130(8): 817-825, 2020 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-31858855

RESUMEN

Purpose: Neuroinflammation was demonstrated to play an important role in the brain injury induced by cerebral ischemia, which was mainly mediated by microglia. MicroRNA-155 (MiR-155) was reported to promote the M1 polarization of microglia and increase neuroinflammation. Resveratrol was identified to have the ability to promote the M2 polarization of microglia and reduce inflammation. Whether resveratrol can promote the M2 polarization of microglia and further inhibit neuroinflammation after cerebral ischemia, and its correlation with miR-155 is unclear. To clarify this, we conducted this study to explore the potential of resveratrol as an effective strategy to treat cerebral ischemia induced neuroinflammation.Materials and methods:The cerebral ischemia mouse model was first constructed by middle cerebral artery occlusion (MCAO). Then resveratrol was intraperitoneally injected at 0 h, 8 h and 18 h after cerebral ischemia. Subsequently, the relative expression of miR-155 and the signature genes of M1 and M2 microglia in injured brain were measured by RT-PCR, and the concentration of pro-inflammatory and anti-inflammatory cytokines were detected by ELISA. Further, the in vitro experiments were also conducted to explore the effect of resveratrol on the inflammation mediated by LPS activated BV2 microglia.Results: Results indicated that the relative expression of miR-155 in ischemia brain and activated BV2 microglia was elevated, while resveratrol reduced the expression of miR-155. Resveratrol promoted the M2 polarization of microglia and reduced neuroinflammation in injured brain and activated BV2 microglia.Conclusions: In conclusion, this research indicated that resveratrol promoted the M2 polarization of microglia and reduced neuroinflammation after cerebral ischemia by inhibiting miR-155.


Asunto(s)
Isquemia Encefálica/tratamiento farmacológico , Inhibidores Enzimáticos/farmacología , Inflamación/tratamiento farmacológico , MicroARNs/efectos de los fármacos , Microglía/efectos de los fármacos , Resveratrol/farmacología , Animales , Isquemia Encefálica/complicaciones , Modelos Animales de Enfermedad , Inhibidores Enzimáticos/administración & dosificación , Infarto de la Arteria Cerebral Media/complicaciones , Inflamación/etiología , Inyecciones Intraperitoneales , Ratones , Resveratrol/administración & dosificación
4.
Biochem Biophys Res Commun ; 501(4): 871-876, 2018 07 02.
Artículo en Inglés | MEDLINE | ID: mdl-29758196

RESUMEN

PURPOSE: Temozolomide (TMZ) is the most frequent adjuvant chemotherapy drug in gliomas. PDL1 expresses on various tumors, including gliomas, and anti-PD-1 antibodies have been approved for treating some tumors by FDA. This study was to evaluate the therapeutical potential of combined TMZ with anti-PD-1 antibody therapy for mouse orthotopic glioma model. METHODS: We performed C57BL/6 mouse orthotopic glioma model by stereotactic intracranial implantation of glioma cell line GL261, mice were randomly divided into four groups: (1) control group; (2) TMZ group; (3) anti-PD-1 antibody group; (4) TMZ combined with anti-PD-1 antibody group. Then the volume or size of tumor was assessed by 7.0 T MRI and immunohistochemistry, and the number of CD4 and CD8 infiltrating cells in brain tumor and spleen was evaluated by immunohistochemistry. Western blot was used to evaluate the expression of PDL1. Furthermore, Overall survival of each group mice was also evaluated. RESULTS: Overall survival was significantly improved in combined group compared to other groups (χ2 = 32.043, p < 0.01). The volume or size of tumor was significantly decreased in combined group compared with other groups (F = 42.771, P < 0.01). And the number of CD4 and CD8 infiltrating cells in brain tumor was also obviously increased in combined group (CD4 F = 45.67, P < 0.01; CD8 F = 53.75, P < 0.01). CONCLUSION: Anti-PD1 antibody combined with TMZ therapy for orthotopic mouse glioma model could significantly improve the survival time of tumor-bear mice. Thus, this study provides the effective preclinical evidence for support clinical chemotherapy combined with immunotherapy for glioma patients.


Asunto(s)
Anticuerpos Antineoplásicos/uso terapéutico , Neoplasias Encefálicas/tratamiento farmacológico , Dacarbazina/análogos & derivados , Glioma/tratamiento farmacológico , Receptor de Muerte Celular Programada 1/inmunología , Animales , Anticuerpos Antineoplásicos/farmacología , Encéfalo/efectos de los fármacos , Encéfalo/metabolismo , Encéfalo/patología , Neoplasias Encefálicas/inmunología , Neoplasias Encefálicas/patología , Linfocitos T CD4-Positivos/efectos de los fármacos , Linfocitos T CD8-positivos/efectos de los fármacos , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Terapia Combinada , Dacarbazina/farmacología , Dacarbazina/uso terapéutico , Modelos Animales de Enfermedad , Glioma/inmunología , Glioma/patología , Humanos , Masculino , Ratones Endogámicos C57BL , Temozolomida , Carga Tumoral/efectos de los fármacos
5.
Opt Express ; 26(23): 30021-30029, 2018 Nov 12.
Artículo en Inglés | MEDLINE | ID: mdl-30469882

RESUMEN

Developing micro/nanoscale wire lasers with single-mode operation and lasing wavelength modulation is essential for realizing their practical applications such as optical communication and saturated spectroscopy. We demonstrated, to the best of our knowledge, the first tunable single-mode microrod laser without complicated micro/nano-manipulation and without additional environmental requirement. In this letter, we realized the wavelength modulation in a single semiconductor microrod simply and directly by changing the axial location of the active region, owing that the active region position plays a key role in determining the lasing mode of microrod lasers. Based on this feature, we proposed a pair of asymmetrical distributed Bragg reflectors (DBRs) with specific spectral selectivity to be induced in a GaN microrod to realize tunable single-mode lasing in a single semiconductor microrod. By using this method, lasing wavelength can be modulated from 369.5 to 375.7 nm flexibly and repeatedly in a 45 µm GaN microrod with the change of the excitation source position. This approach demonstrates a big application potential in numerous fields consisting of optical telecommunication and environmental monitoring.

6.
Opt Express ; 25(18): 21025-21036, 2017 Sep 04.
Artículo en Inglés | MEDLINE | ID: mdl-29041512

RESUMEN

Developing micro/nanoscale wire (MNW) lasers with single-mode operation is critical for realizing their practical applications, however, most reported MNW lasers operate in multi-modes, because lacking of mode selection mechanisms. In this work, a simple and direct way to realize stable, single-mode MNW laser without complicated micro/nano-manipulation was demonstrated. We have found and proved that the position of the active region plays a key role in determining the lasing mode of MNW lasers, which can be used to realize single-mode lasing in MNWs. We propose self-selection mechanism of Fabry-Pérot MNW cavity for single-mode lasing due to location-dependent field distribution in MNWs, which is characterized by suppressing the multiple longitudinal mode oscillation of the MNW laser. GaN MNW lasers with different lengths and diameters have been fabricated, verifying the self-selection mechanism of the cavity experimentally. Moreover, we demonstrate the single-mode, room temperature optically pumped MNW laser with an extremely low threshold (~40 kW/cm2) in condition of appropriate cavity length, opening an opportunity to realize stable single-mode, low-threshold MNW laser for easy integration in constructing micro/nanoscale photonic and optoelectronic circuits and devices.

7.
Ecotoxicol Environ Saf ; 114: 312-7, 2015 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-25037070

RESUMEN

The aim of this study was to evaluate antioxidative responses in roots, stem and leaves of four alfalfa cultivars to different concentrations of zinc (Zn) (0, 300, 600 and 900 µM) for 23 days. Among the four cultivars, Aohan displayed the highest Zn concentrations in tissues and the largest Zn amount in aerial parts. Zn stress induced the production of H2O2 and increased the content of free proline and activities of antioxidative enzymes in roots, stem and leaves of Aohan. Based on the above results, we concluded that Aohan is superior to other three cultivars for Zn phyto-remediation, which indicated that Aohan is a novel Zn accumulator and able to tolerate Zn-induced toxicity by activating the antioxidative defense system.


Asunto(s)
Antioxidantes/metabolismo , Medicago sativa/efectos de los fármacos , Contaminantes del Suelo/toxicidad , Zinc/toxicidad , Peróxido de Hidrógeno/metabolismo , Medicago sativa/enzimología , Medicago sativa/metabolismo , Hojas de la Planta/efectos de los fármacos , Hojas de la Planta/metabolismo , Raíces de Plantas/efectos de los fármacos , Raíces de Plantas/metabolismo , Prolina/metabolismo
8.
J Appl Psychol ; 109(1): 13-38, 2024 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-37535530

RESUMEN

The phenomenon of group turnover has generated substantial yet disconnected scholarly interests. Despite valuable insights gained from the collective turnover literature as well as parallel research concerning related or coordinated quitting, a holistic understanding of the unique group turnover phenomenon is needed, both to synthesize existing research across multiple domains and disciplines and to kindle new inquiries regarding its dynamic nature and developmental process. To this end, we begin by conducting an integrative review of research relating to group turnover, reinterpreting it by identifying its common pathways as a function of varying triggers, temporal patterns, and departure destinations. We then leverage the groups literature to explicate group turnover's self-reinforcing and dynamic nature and propose a three-dimensional Interdependence, Temporality, and Emergence (ITE) framework that accounts for its developmental process. Using this framework, we develop an illustrative set of propositions regarding how ITE-related group properties affect the extent to which individual departures might escalate into group turnover of a larger scale and faster speed. Our emphasis on groups as a unique unit of reference thus provides an important conceptual refinement and extension for understanding collective turnover-shifting from a static focus on aggregate exit (rates) to a dynamic focus on the often-coordinated, temporally evolving nature of multiple group member quit events. (PsycInfo Database Record (c) 2024 APA, all rights reserved).


Asunto(s)
Reorganización del Personal , Humanos
9.
3D Print Addit Manuf ; 11(2): e751-e763, 2024 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-38694835

RESUMEN

Binder jetting (3DP) is a kind of additive manufacturing at room temperature and atmospheric environment, which can reduce the risk of magnesium alloy forming. Magnesium alloy powder is bonded to a certain structure by a binder, so the appropriate binder is very important in 3DP. In this study, according to the characteristics of magnesium alloy, a simple and easy-to-obtain water-based low-molecular alcohol binder was used to reduce the difficulty of magnesium alloy 3DP. Additionally, we use COMSOL Multiphysics simulation software to establish a simulation model of the movement and deposition process of the binder. The results show that the increase in jet velocity will increase the quality and saturation of droplets. More importantly, the larger the jet velocity is, the larger the spreading width of the binder droplet after impacting the powder bed, which seriously affects the dimensional accuracy of the green part. In addition, lower binder saturation will weaken the formation of interparticle bonding neck and cannot form a stable structure. Furthermore, we analyzed the bond reactants of the binder and magnesium alloy powder, which eventually decompose into MgO, and the experimental results show that the final sintered sample has considerable performance.

10.
Sci Rep ; 13(1): 1925, 2023 Feb 02.
Artículo en Inglés | MEDLINE | ID: mdl-36732441

RESUMEN

This paper proposes an advanced Reinforcement Learning (RL) method, incorporating reward-shaping, safety value functions, and a quantum action selection algorithm. The method is model-free and can synthesize a finite policy that maximizes the probability of satisfying a complex task. Although RL is a promising approach, it suffers from unsafe traps and sparse rewards and becomes impractical when applied to real-world problems. To improve safety during training, we introduce a concept of safety values, which results in a model-based adaptive scenario due to online updates of transition probabilities. On the other hand, a high-level complex task is usually formulated via formal languages, including Linear Temporal Logic (LTL). Another novelty of this work is using an Embedded Limit-Deterministic Generalized Büchi Automaton (E-LDGBA) to represent an LTL formula. The obtained deterministic policy can generalize the tasks over infinite and finite horizons. We design an automaton-based reward, and the theoretical analysis shows that an agent can accomplish task specifications with the maximum probability by following the optimal policy. Furthermore, a reward shaping process is developed to avoid sparse rewards and enforce the RL convergence while keeping the optimal policies invariant. In addition, inspired by quantum computing, we propose a quantum action selection algorithm to replace the existing [Formula: see text]-greedy algorithm for the balance of exploration and exploitation during learning. Simulations demonstrate how the proposed framework can achieve good performance by dramatically reducing the times to visit unsafe states while converging optimal policies.

11.
3D Print Addit Manuf ; 10(5): 992-1002, 2023 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-37886410

RESUMEN

Personalized insoles manufactured with selective laser sintering (SLS) technology are popular especially for exercisers and patients with foot diseases. However, insufficient strength and toughness of personalized insoles would result in crack and even fracture. To address these deficiencies and fill the research shortages in this area, optimization of process parameters and design of cell structures are conducted to improve the mechanical performance of insoles in this topic. First, six sets of process parameters in terms of energy density were designed for parameter optimization. The energy density of 0.08 J/mm2 was affirmed to be the finest selection. Then, specific cell structures featuring both whale shark and ancient soldier armor (WS structures for short) with various curvature radius were established to act on the bottom of the insole to further strengthen the personalized insoles. It was shown that the WS14 structure exhibited the best performance characteristics. Finally, a personalized insole with the array of WS14 structures was developed with SLS under the optimum energy density of 0.08 J/mm2. Finite element method analysis and exercising testing were performed to evaluate the insole performance. The result reveals that a more uniform stress distribution is attained of the WS14 personalized insole, and the fracture problem is indeed solved.

12.
3D Print Addit Manuf ; 10(5): 1064-1071, 2023 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-37886419

RESUMEN

In selective laser sintering (SLS), process parameters are essential to fabricate outstanding mechanical properties products. In this research, process parameters of porous Polyamide 12 (PA12) scaffold were investigated for the sake of obtaining superior mechanical properties. The area energy density (AED) determined by laser power, scanning speed, and scanning space was employed as the main index to assess process parameters. Six groups with different AED were planed, and then cubic and cylindrical samples were modeled and fabricated with PA12 powders via SLS. Afterward, mechanical properties of the samples were measured and studied to achieve optimum parameters. After a detailed comparison of micrograph, density, dimensional accuracy, and mechanical properties of samples under different AED, laser power of 16 W, scanning speed of 2500 m/s, and scanning space of 0.12 mm were found to be the optimum parameters. Further, a 60% uniform porosity scaffold was fabricated with the optimum parameters to measure mechanical properties for evaluating the optimized results, which were elastic modulus of 87.79 MPa, yield strength of 8.25 MPa, and Poisson's ratio of 0.3. Finite element simulation was also performed, and the results exhibited a good agreement with the experimental behaviors.

13.
J Mech Behav Biomed Mater ; 145: 106000, 2023 09.
Artículo en Inglés | MEDLINE | ID: mdl-37423007

RESUMEN

Composite scaffolds have been extensively studied in bone tissue engineering, which can achieve excellent properties that cannot be obtained by a single material. In this study, the effect of hydroxyapatite (HA) on the reliability of polyamide 12 (PA12) scaffold for bone graft was explored in terms of mechanical and biological properties. Thermal properties testing showed that no physical or chemical reaction occurs in the prepared PA12/HA composite powders. Further, compression experiments showed that adding a small amount of HA promoted the mechanical properties of the scaffold, while excessive HA results in agglomeration and impairs the PA12/HA scaffold. For the scaffolds with the porosity of 65%, the 96% PA12/4% HA scaffold has a 7.3% higher yield strength and a 13.5% higher compressive modulus than the pure PA12 scaffold while the strength of the 88% PA12/12% HA scaffold decreases by 35.6%. Furthermore, contact angle and CCK-8 tests confirmed that 96% PA12/4% HA scaffold effectively improved the hydrophilicity and biocompatibility of the scaffold. Its OD value on the 7th day is 0.949, which is significantly higher than that of other groups. In summary, PA12/HA composites have good mechanical properties and biocompatibility, which can be used as an effective strategy in bone tissue engineering.


Asunto(s)
Durapatita , Andamios del Tejido , Durapatita/química , Andamios del Tejido/química , Reproducibilidad de los Resultados , Ingeniería de Tejidos/métodos , Porosidad , Rayos Láser
14.
J Mech Behav Biomed Mater ; 143: 105915, 2023 07.
Artículo en Inglés | MEDLINE | ID: mdl-37257310

RESUMEN

Developing a functional gradient scaffold compatible with the fantastic biological and mechanical properties of natural bone tissue is imperative in bone tissue engineering. In this work, the stretch-dominated (cubical and circular) and bending-dominant (diamond and gyroid) pore styles were employed to design custom-graded scaffolds based on the curve interference method and then were fabricated by selective laser sintering (SLS) using polyamide 12 (PA12) powder. Subsequently, the mechanical behavior, failure mechanism, and energy absorption performance of porous structures were investigated via compression experiments and finite element (FE) simulation. The results indicated that the stretch-dominated radial gradient structures entire exhibited transverse shear failure and the bending-dominant radial gradient structures whole exhibited progressive destruction, while all of the axial gradient scaffolds suffered a predictable layer-by-layer fracture. Among them, the bending-dominated radial gradient structure of gyroid had been proven to sustain stronger deformability and energy absorption capacity. Meanwhile, the FE method powerfully predicted the mechanical behavior of the scaffold, and this research thereby possessed significant implications for the development of bone tissue engineering.


Asunto(s)
Ingeniería de Tejidos , Andamios del Tejido , Andamios del Tejido/química , Ingeniería de Tejidos/métodos , Nylons , Porosidad , Rayos Láser
15.
Acad Radiol ; 2023 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-38042623

RESUMEN

RATIONALE AND OBJECTIVES: The aim of this study was to explore the potential of a newly developed dark-blood imaging technique to improve image quality and plaque visibility in head and neck computed tomography (CT) angiography. MATERIALS AND METHODS: Patients who underwent triphasic head and neck CT angiography scans from August 2021 to March 2023 were retrospectively enrolled (mean age 67.23 ± 10.81 [SD] years, range 43-85 years, 64.7% male). The CT protocol consists of pre-contrast, arterial and delayed phases. Dark-blood images were postprocessed with the contrast-enhancement boost (CE-boost) technique. The quantitative assessment involved evaluating the CT value, image noise, contrast-to-noise ratio (CNR), and signal-to-noise ratio (SNR) of calcified plaque and non-calcified plaque. The plaque CNR relative to the vessel lumen (CNRplaque-lumen), vessel wall (CNRplaque-wall), and adjacent muscle (CNRplaque-muscle) was respectively calculated. Two experienced radiologists independently evaluated the CT images (5, best; 1, worst) by four characteristics including calcified plaque visibility, non-calcified plaque visibility, diagnostic confidence, and overall image quality. Inter-rater variability was also evaluated. The artery stenosis rate and plaque burden on dark-blood images were measured and compared with arterial phases. The intraclass correlation coefficient (ICC) was used for consistency analysis. The diagnostic accuracy of dark-blood images for the stenosis rate was evaluated by the area under the curve (AUC). RESULTS: A total of 43 patients with 54 calcified plaques and 34 non-calcified plaques were assessed in this study. When compared with pre-contrast and delayed phase, dark-blood images yielded significantly higher CNRplaque-lumen and CNRplaque-muscle of calcified (219.79 ± 159.20 and 181.23 ± 112.12, respectively) and non-calcified (30.30 ± 29.11 and 6.28 ± 4.75, respectively) plaques (all p < 0.001). Calcified plaque SNR of dark-blood showed equal or slightly lower than other phases (p > 0.05 or p = 0.02). A major increase was observed in the non-calcified plaque SNR of dark-blood compared to the arterial phase (5.56 ± 3.71 vs. 4.23 ± 3.56, p = 0.02), although there were no apparent differences compared to pre-contrast and delayed phases (p > 0.05). In subjective analyzes, the calcified plaque visibility (4.99 ± 0.07), non-calcified plaque visibility (4.62 ± 0.48), overall image quality (4.81 ± 0.34), and diagnostic confidence (4.74 ± 0.36) in dark-blood images dominated the highest scores (p < 0.001). The subjective scores of radiologists exhibited good consistency (all kappa value>0.7). The dark-blood image and the arterial phase image exhibited good consistency in identifying the stenosis rate (p < 0.001). In the evaluation of plaque burden, the interobserver agreement for dark-blood images was higher compared to arterial phase images (ICC = 0.870 vs. 0.729). CONCLUSIONS: Compared to conventional triphasic head and neck CT angiography, the CE-boost derived dark-blood imaging demonstrated a significant improvement in image quality and visibility for both calcified and non-calcified plaque assessment.

16.
Front Endocrinol (Lausanne) ; 14: 1250755, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-38174332

RESUMEN

Objective: This study aims to access the efficacy of the binasal speculum in endoscopic endonasal surgery by evaluating clinical outcomes and examining its utility through process-based performance measures in both surgeons and assistants. Methods: A total of 59 patients with lesions in sellar region who underwent endoscopic endonasal surgery with the binasal speculum between September 2020 and March 2023 were included in this study. We assessed the extent of resection and documented postoperative nasal condition. Both surgeons and assistants completed post-use surveys to exam the utility of the binasal speculum and provide an overall grading. Results: Gross total resection (GTR) was successfully achieved in 94.9% (56/59) of patients, with subtotal resection (STR) observed in 5.1% (4/59) of patients. Intraoperative cerebrospinal fluid (CSF) leakage occurred in 23.7% (14/59) of cases, and nasoseptal flap (NSF) reconstruction was required in 55.9% (33/59) of cases. The nasal airway patency rapidly recovered within 14 days in a significant majority of patients (94.9%, 56/59). Moreover, olfactory function was regained within three months postoperatively by 91.5% (54/59) of patients. The overall post-use survey mean score was 26.4. Specifically, surgeons had a mean score of 26.5, while assistants had a slightly lower mean score of 26.2. The mean overall grading for the binasal speculum was 3. Both surgeons and assistants provided a mean overall grading of 3. Conclusion: The binasal speculum provides nasal mucosa protection and reduces the risk of an endoscopic lens clouded by mucosa or blood. It plays a crucial role in accurate guidance and facilitates the swift delivery of surgical instruments, particularly in left-blinded nasal cavities. The binasal speculum reduces the learning curve, especially for endoscopic surgeons with limited experience, while enhancing collaboration and coordination between surgeons and assistants during surgery. Both surgeons and assistants rated the overall utility of the binasal speculum as "excellent."


Asunto(s)
Nariz , Procedimientos de Cirugía Plástica , Humanos , Estudios Retrospectivos , Colgajos Quirúrgicos/cirugía , Pérdida de Líquido Cefalorraquídeo/etiología , Instrumentos Quirúrgicos
17.
J Mater Chem B ; 10(46): 9699-9712, 2022 11 30.
Artículo en Inglés | MEDLINE | ID: mdl-36398681

RESUMEN

Irregular porous structures for guided bone regeneration applications have gained increasing attention as they are similar to human bone and more suitable for bone tissue growth. However, pore irregularity as a critical characteristic has been poorly explored. This study proposed a method for parametrically designing porous scaffolds based on a Voronoi tessellation which were manufactured by selective laser sintering (SLS) using the polyamide 12 (PA12) material. The deformation mechanism and energy absorption properties of the prepared Voronoi scaffolds were investigated by quasi-static compression experiments. The results demonstrated that the Voronoi scaffold underwent bending deformation subsequent to transverse expansion under compression, and the Voronoi scaffold simultaneously had been indicated to be effective in improving the carrying capacity and energy absorption performance. Subsequently, computational fluid dynamics (CFD) and cell proliferation tests were introduced to comprehensively assess the influence of the scaffolds on cell growth. CFD analysis showed that the permeability of the surveyed scaffolds is between 3.65 × 10-8 and 12.05 × 10-8 m2 similar to that of natural cancellous bone. The cell test expressed that the scaffold exhibits good cell activity, which can be used to promote cell adhesion and migration with superior potential for development and application.


Asunto(s)
Huesos , Ingeniería de Tejidos , Humanos , Porosidad , Permeabilidad , Ingeniería
18.
J Mech Behav Biomed Mater ; 126: 105052, 2022 02.
Artículo en Inglés | MEDLINE | ID: mdl-34933156

RESUMEN

Scaffolds with favorable biological characteristics and controlled functional gradient architectures are preferable for the repair of damaged tissues in bone tissue engineering. In this study, the triply periodic minimal surfaces (TPMS) were introduced to design functional gradient porous scaffolds based on Primitive lattices which were then manufactured by selective laser sintering (SLS) using pure polyamide12 (PA12) material and PA12/hydroxyapatite (HA) composite material. The mechanical properties and permeability of the scaffolds were then evaluated by mechanical compression experiments and computational fluid dynamics (CFD) analysis. The radial-graded scaffold was found to have superior good mechanical properties and permeability and be favorable for the subsequent growth of bone tissue. Further, the optimal PA12/HA composition was determined by analyzing the effect of the addition of HA particles on the hydrophilicity and mechanical properties of the composite scaffold. Additionally, the cytotoxicity tests were performed to evaluate the effects of PA12/HA gradient scaffold on cell growth. The obtained results demonstrate that the radial gradient scaffold with 15% HA addition exhibits a feasible combination of comprehensive performance and biological activity, indicating a great application potential in the field of bone tissue engineering.


Asunto(s)
Durapatita , Andamios del Tejido , Huesos , Rayos Láser , Porosidad , Ingeniería de Tejidos
19.
Neuropsychologia ; 167: 108164, 2022 03 12.
Artículo en Inglés | MEDLINE | ID: mdl-35085597

RESUMEN

Malevolent creativity, as one dark side of creativity, refers to manifestations people propose to harm themselves or others materially, mentally, or physically in an innovative way. This study aimed to explore the neural correlates of malevolent creative idea generation using task-based static and dynamic functional connectivity (FC) analysis across different time periods. We collected 34 participants who performed malevolent creativity task (MCT), benevolent creativity task (BCT), and realistic presented problems task (RPPT) in the fMRI scanner. The static connectivity analysis showed lower FC strength and global and local efficiency between the dorsal somatomotor network (dSMN), visual network (VN), default mode network (DMN), and reward network (RN) in MCT and RPPT than BCT. Dynamic connectivity analysis showed higher dynamic network reconfiguration in the DMN during MCT than BCT and RPPT. The behavioral results showed higher anxiety, anger, and lower pleasure in MCT than in BCT and RPPT. These findings indicate that the dSMN, VN, RN, and DMN are specifically involved in malevolent creative idea generation. Our findings provide the neural correlates of malevolent creative idea generation using neuroimaging techniques for the first time, which provides insight into the future study of malevolent creativity.


Asunto(s)
Mapeo Encefálico , Encéfalo , Encéfalo/diagnóstico por imagen , Mapeo Encefálico/métodos , Creatividad , Humanos , Imagen por Resonancia Magnética
20.
J Appl Psychol ; 107(6): 1020-1030, 2022 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-34647784

RESUMEN

Although job embeddedness has consistently been shown to be associated with positive workplace behaviors, our theoretical understanding of such associations remains far behind our empirical knowledge. In particular, it is unclear how job embeddedness goes beyond its common conceptualization as "stuckness" to motivate employees' discretionary, change-oriented behaviors at work. To this end, we trace the original theoretical foundation of job embeddedness theory in field theory and establish its theoretical connection to social identity theory. We propose that increased organizational identification is an intrinsic psychological mechanism through which job embeddedness motivates proactive behaviors from employees. Further informed by field theory, we also examine the implications of job embeddedness change over time. We propose that a more positive trajectory of embeddedness over time contributes to enhanced organizational identification and employee proactivity, above and beyond the absolute level of embeddedness. We report a longitudinal study that surveyed 264 employees at three points in time over the course of 1 year and provide substantial support for the hypotheses. Implications of our work are discussed. (PsycInfo Database Record (c) 2022 APA, all rights reserved).


Asunto(s)
Organizaciones , Lugar de Trabajo , Humanos , Satisfacción en el Trabajo , Estudios Longitudinales , Identificación Social , Encuestas y Cuestionarios , Lugar de Trabajo/psicología
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