Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 51
Filtrar
1.
J Biophotonics ; : e202400287, 2024 Oct 08.
Artigo em Inglês | MEDLINE | ID: mdl-39379333

RESUMO

Diabetic retinopathy is one of the most prevalent microvascular complications of diabetes mellitus, and photoacoustic imaging is an effective method for imaging diabetic retinal vessels. Photoacoustic imaging is an emerging noninvasive imaging method based on the photoacoustic effect, which offers advantages of contrast, resolution, and depth imaging. Appropriate photoacoustic reconstruction methods are essential for obtaining high-quality photoacoustic images. In this study, a multi-input self-attention multiscale feature fusion network (SAMF-Net) is proposed for photoacoustic reconstruction. The algorithm accepts two inputs, namely the original photoacoustic signal and the traditional reconstructed image. Furthermore, a global feature extraction module based on the self-attention mechanism is employed to focus on the global information. The results demonstrate that the proposed method exhibits superior reconstruction capability under different sparse detection views. The method has instructive value for photoacoustic image reconstruction and has the potential for further application in the diagnosis of diabetic retinopathy.

2.
Polymers (Basel) ; 16(19)2024 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-39408409

RESUMO

Fused deposition modeling (FDM) 3D printing has the advantages of a simple molding principle, convenient operation, and low cost, making it suitable for the production and fabrication of complex structural parts. Moving forward to mass production using 3D printing, the major hurdle to overcome is the achievement of high dimensional stability and adequate mechanical properties. In particular, engineering plastics require precise dimensional accuracy. In this study, we overcame the issues of FDM 3D printing in terms of ternary material compounds for polyamides with gradient structures. Using multi-walled carbon nanotubes (MWCNTs) and boron nitride (BN) as fillers, polyamide 6 (PA6)-based 3D-printed parts with high dimensional stability were prepared using a single-nozzle, two-component composite fused deposition modeling (FDM) 3D printing technology to construct a gradient structure. The ternary composites were characterized via DSC and XRD to determine the optimal crystallinity. The warpage and shrinkage of the printed samples were measured to ensure the dimensional properties. The mechanical properties were analyzed to determine the influence of the gradient structures on the composites. The experimental results show that the warpage of pure polymer 3D-printed parts is as high as 72.64%, and the introduction of a gradient structure can reduce the warpage to 3.40% by offsetting the shrinkage internal stress between layers. In addition, the tensile strength of the gradient material reaches up to 42.91 MPa, and the increasing filler content improves the interlayer bonding of the composites, with the bending strength reaching up to 60.91 MPa and the interlayer shear strength reaching up to 10.23 MPa. Therefore, gradient structure design can be used to produce PA6 3D-printed composites with high dimensional stability without sacrificing the mechanical properties of PA6 composites.

3.
Int J Biol Macromol ; 279(Pt 2): 135055, 2024 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-39216589

RESUMO

Bone injury represents an urgent clinical problem, and implantable bioscaffolds offer suitable means for replacing and regenerating damaged tissues. This paper proposes an in-situ foaming printing method employing material extrusion additive manufacturing technology and physical foaming to prepared poly(lactic acid)/chitin nanocrystals (CHNCs) microporous composite scaffolds, featuring pore sizes ranging from 9 ± 5 µm. This method offers a novel strategy for the preparation of poly(lactic acid)-based scaffolds with good biocompatibility. Material characterization and mechanical property testing demonstrated that the in-situ foaming printed PLA scaffolds exhibited excellent foam printability, and the expansion ratio and compression properties of the scaffolds could be adjusted by modifying the CHNCs concentration and the printing speed, achieving a compression modulus between 39.2 MPa and 54.3 MPa. Furthermore, at equivalent foaming multiplicity (1.5-2.6 times), the compression modulus increased by nearly 100 % compared to previously reported PLA-based foam scaffolds. Importantly, the PLA/CHNCs scaffolds produced via in-situ foaming exhibited superior biocompatibility compared to directly printed PLA scaffolds. This PLA/CHNCs composite scaffold provides a promising approach to addressing and repairing bone defects.


Assuntos
Quitina , Nanopartículas , Poliésteres , Impressão Tridimensional , Engenharia Tecidual , Alicerces Teciduais , Poliésteres/química , Alicerces Teciduais/química , Engenharia Tecidual/métodos , Quitina/química , Nanopartículas/química , Porosidade , Osso e Ossos/efeitos dos fármacos , Materiais Biocompatíveis/química , Teste de Materiais , Humanos , Animais
4.
Appl Opt ; 63(5): 1217-1221, 2024 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-38437300

RESUMO

Wavelength-tunable orbital angular momentum (OAM) lasers with controllable topological charges have the potential for serving as light sources for large-capacity optical communication by combining conventional wavelength division multiplexing (WDM) with OAM mode-division multiplexing (OAM-MDM). In this study, we demonstrate a wavelength-tunable Tm-bulk laser that can control OAM states in the 2-µm spectral range. The excitation conditions for different Laguerre-Gaussian (L G 0,l ) modes in a bulk laser cavity are theoretically determined by measuring the spatial propagation dynamics of the annular pump beam. As a proof-of-principle study, we experimentally generate OAM states of |ℏ| and |2ℏ| from a T m:Y 2 O 3 ceramic laser with a tunable emission wavelength using a Lyot filter (LF). The spatial properties of the scalar optical vortices are well conserved during wavelength tuning, indicating the feasibility of our approach for producing wavelength-tunable structured light. These OAM laser sources, which are characterized by their robustness and compactness, have potential applications in various areas such as optical communications, quantum optics, super-resolution microscopes, and more.

5.
Nanomaterials (Basel) ; 13(19)2023 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-37836352

RESUMO

Polymer-based dielectric composites are of great importance in advanced electronic industries and energy storage because of their high dielectric constant, good processability, low weight, and low dielectric loss. FDM (Fused Deposition Modeling) is a greatly accessible additive manufacturing technology, which has a number of applications in the fabrication of RF components, but the unavoidable porosity in FDM 3D-printed materials, which affects the dielectric properties of the materials, and the difficulty of large-scale fabrication of composites by FDM limit its application scope. This study's main focus is on how the matrix, filler, interface, and FDM 3D printing parameters influence the electrical properties of FDM-printed polymer-based dielectric composites. This review article starts with the fundamental theory of dielectrics. It is followed by a summary of the factors influencing dielectric properties in recent research developments, as well as a projection for the future development of FDM-prepared polymer-based dielectric composites. Finally, improving the comprehensive performance of dielectric composites is an important direction for future development.

6.
Polymers (Basel) ; 15(18)2023 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-37765576

RESUMO

Additive manufacturing of carbon-fiber-reinforced polymer (CFRP) has been widely used in many fields. However, issues such as inconsistent fiber orientation distribution and void formation during the layer stacking process have hindered the further optimization of the composite material's performance. This study aimed to address these challenges by conducting a comprehensive investigation into the influence of carbon fiber content and printing parameters on the micro-morphology, thermal properties, and mechanical properties of PA6-CF composites. Additionally, a heat treatment process was proposed to enhance the interlayer bonding and tensile properties of the printed composites in the printing direction. The experimental results demonstrate that the PA6-CF25 composite achieved the highest tensile strength of 163 MPa under optimal heat treatment conditions: 120 °C for 7.5 h. This corresponds to a significant tensile strength enhancement of 406% compared to the unreinforced composites, which represents the highest reported improvement in the current field of CFRP-fused deposition 3D printing. Additionally, we have innovatively developed a single-layer monofilament CF-OD model to quantitatively analyze the influence of fiber orientation distribution on the properties of the composite material. Under specific heat treatment conditions, the sample exhibits an average orientation angle µ of 0.43 and an orientation angle variance of 8.02. The peak frequency of fiber orientation closely aligns with 0°, which corresponds to the printing direction. Finally, the study explored the lightweight applications of the composite material, showcasing the impressive specific energy absorption (SEA) value of 17,800 J/kg when implementing 3D-printed PA6-CF composites as fillers in automobile crash boxes.

7.
Appl Opt ; 62(17): 4505-4511, 2023 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-37707143

RESUMO

A high-energy and high-average-power pulsed fiber laser has been investigated in a master oscillator power amplifier (MOPA) configuration seeding with a diode laser at a programmed pulse duration of ∼250ns. The fiber amplifier successfully demonstrates the pulse with 21.4 mJ at the repetition rate of 50 kHz and a maximum average output power of 1535 W with a slope efficiency of 81.6% at 250 kHz. To overcome fiber nonlinearities such as stimulated Raman scattering (SRS) and self-phase modulation (SPM), extra-large mode area ytterbium (Yb)-doped step-index dual cladding fiber has been utilized as gain fiber in the MOPA laser system. The gain saturation effect in the power amplifier was greatly mitigated by the programmed seed signal. This pulse-shaped MOPA system can provide practical applications in many fields such as laser cleaning, paint stripping, and other applications requiring special pulse shapes.

8.
Front Oncol ; 13: 1166775, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37427105

RESUMO

Objective: Ablation is a common treatment for hepatocellular carcinoma (HCC). This study aimed to assess research trends in the ablation treatment of HCC using bibliometric analysis. Methods: Publications between January 1, 1993 and December 31, 2022 were retrieved from the Web of Science database. The bibliometrix package from R software, CiteSpace, VOSviewer and an online analytical platform were used for data analysis and plotting. Results: A total of 4,029 publications were retrieved from the Web of Science database between 1993 and 2022. The annual growth rate of publication numbers was 10.14%. China had the largest number of publications in the field of HCC ablation. China and the United States of America have the most notable cooperation. Sun Yat-sen University had the largest number of publications in the field of HCC ablation. The most relevant journals were Hepatology, Journal of Hepatology, Gastroenterology, and Radiology. High-frequency keywords mainly focused on "therapy," "resection," "radiofrequency ablation" and "survival". Conclusions: With the increase in related publications, the research direction of ablation treatment of HCC is mainly focused on "therapy," "resection," "radiofrequency ablation" and "survival", and the ablation treatment method has gradually changed from percutaneous ethanol injection to radiofrequency ablation and microwave ablation. Irreversible electroporation may become the main method of ablation therapy in the future.

9.
Front Microbiol ; 14: 1050635, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37032866

RESUMO

The increased demand for rare earth resources has led to an increase in the development of rare earth mines (REMs). However, the production of high-concentration leaching agents (SO4 2-) and heavy metals as a result of rare earth mining has increased, necessitating the removal of contaminants. Here, a series of experiments with different remediation measures, including control (CK), sulfate-reducing bacteria (SRB) alone (M), chemicals (Ca(OH)2, 1.5 g/kg) plus SRB (CM-L), chemicals (Ca(OH)2, 3.0 g/kg) plus SRB (CM-M), and chemicals (Ca(OH)2, 4.5 g/kg) plus SRB (CM-H), were conducted to investigate the removal effect of SO4 2-, Pb, Zn, and Mn from the REM soil. Then, a high-throughput sequencing technology was applied to explore the response of bacterial community diversity and functions with different remediation measures. The results indicated that CM-M treatment had a more efficient removal effect for SO4 2-, Pb, Zn, and Mn than the others, up to 94.6, 88.3, 98.7, and 91%, respectively. Soil bacterial abundance and diversity were significantly affected by treatments with the inoculation of SRB in comparison with CK. The relative abundance of Desulfobacterota with the ability to transform SO4 2- into S2- increased significantly in all treatments, except for CK. There was a strong correlation between environmental factors (pH, Eh, SO4 2-, Pb, and Zn) and bacterial community structure. Furthermore, functional prediction analysis revealed that the SRB inoculation treatments significantly increased the abundance of sulfate respiration, sulfite respiration, and nitrogen fixation, while decreasing the abundance of manganese oxidation, dark hydrogen oxidation, and denitrification. This provides good evidence for us to understand the difference in removal efficiency, bacterial community structure, and function by different remediation measures that help select a more efficient and sustainable method to remediate contaminants in the REM soil.

10.
Microb Pathog ; 175: 105970, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36621696

RESUMO

Recent studies have demonstrated that dysbiosis of the gut microbiota is associated with psoriasis, but these studies showed some conflicting results. Our study examined differences in microbiome composition associated in people with psoriasis and those without. Comparing individuals with their healthy partners was a second strategy. We explored the fecal microbiota among 32 nontreated plaque psoriasis patients, 15 healthy controls and 17 healthy couples by metagenomic gene sequencing. The relative levels of intestinal microbiota of the psoriasis cohort differed from those in healthy controls and these patients' partners. However, there was no microbial diversity among these three cohorts. On the level of the phylum, Firmicutes and Bacteroidetes' relative abundances were reversed. Escherichia coli was significantly enriched in the psoriasis group compared with the healthy people and the healthy spouses. Gene functional analysis indicated that Ribosome (ko03010) was upregulated, Flagellar assembly (ko02040) and Bacterial chemotaxis (ko02030) were downregulated in the psoriasis cohort compared with the healthy individuals and the healthy spouses. The microbiota in severe psoriasis patients differed from those with milder conditions. These findings strongly support the association between intestinal flora and psoriasis. It is necessary to perform more meaningful experiments to identify whether the differences of gut microbiota are the cause or consequences of psoriasis in future.


Assuntos
Microbioma Gastrointestinal , Microbiota , Psoríase , Humanos , Microbioma Gastrointestinal/genética , Microbiota/genética , Bactérias/genética , Bacteroidetes , Fezes/microbiologia , Disbiose/microbiologia , RNA Ribossômico 16S/genética
11.
Front Plant Sci ; 13: 1079087, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36483950

RESUMO

Ultraviolet-B (UV-B) radiation is an environmental signal that affects the accumulation of secondary metabolites in plants. In particular, UV-B promotes flavonoid biosynthesis, leading to improved fruit quality. To explore the underlying molecular mechanism, we exposed blueberry (Vaccinium corymbosum) calli to UV-B radiation and performed a transcriptome deep sequencing (RNA-seq) analysis to identify differentially expressed genes (DEGs). We detected 16,899 DEGs among different treatments, with the largest number seen after 24 h of UV-B exposure relative to controls. Functional annotation and enrichment analysis showed a significant enrichment for DEGs in pathways related to plant hormone signal transduction and phenylpropanoid and flavonoid biosynthesis. In agreement with the transcriptome data, flavonol, anthocyanin and proanthocyanidin accumulated upon UV-B radiation, and most DEGs mapping to the phenylpropanoid and flavonoid biosynthetic pathways using the KEGG mapper tool were upregulated under UV-B radiation. We also performed a weighted gene co-expression network analysis (WGCNA) to explore the relationship among genes involved in plant hormone signal transduction, encoding transcription factors or participating in flavonoid biosynthesis. The transcription factors VcMYBPA1, MYBPA2.1, MYB114, MYBA2, MYBF, and MYB102 are likely activators, whereas MYB20, VcMYB14, MYB44, and VcMYB4a are inhibitors of the flavonoid biosynthetic pathway, as evidenced by the direction of correlation between the expression of these MYBs and flavonoid biosynthesis-related genes. The transcription factors bHLH74 and bHLH25 might interact with MYB repressors or directly inhibited the expression of flavonoid biosynthetic genes to control flavonoid accumulation. We also observed the downregulation of several genes belonging to the auxin, gibberellin and brassinosteroid biosynthetic pathways, suggesting that MYB inhibitors or activators are directly or indirectly regulated to promote flavonoid biosynthesis under UV-B radiation.

12.
World J Surg Oncol ; 20(1): 396, 2022 Dec 13.
Artigo em Inglês | MEDLINE | ID: mdl-36510298

RESUMO

Objective laparoscopic surgical excision is the recommended treatment for liver cancers, yet its benefits in patients aged 60 and older remain poorly understood. Thus, this study evaluated the feasibility, safety, and clinical outcomes of laparoscopic hepatectomy for patients aged 60 and older with intrahepatic cholangiocarcinoma (ICC).MethodsAfter screening, 107 patients who underwent hepatectomy for ICC were enrolled and grouped into either laparoscopic (LH) or open hepatectomy (OH) groups. Baseline characteristics, pathological findings, and long-term outcomes were compared between the two groups. Independent prognostic factors for overall survival (OS) and disease-free survival (DFS) were identified using univariate and multivariate analyses.ResultsAmong baseline characteristics and pathological findings, only pre-operative albumin was higher in the LH group. The LH group had more favorable short-term outcomes such as incision length, level of postoperative total bilirubin, and length of postoperative stays than the OH group. The postoperative complication, lymph node dissection and R0 resection rate, and long-term outcomes including OS and DFS were not significantly different between the two groups. Cancer Antigen-19-9(CA-19-9) and pathological differentiation were independent prognostic factors for OS, whereas CA-19-9 and neutrophil count were independent prognostic factors for DFS.ConclusionLH is safe, reliable, and feasible for treatment of ICC patients aged 60 and older as it had better short-term clinical outcomes than OH and achieved long-term prognoses that were comparable to those of OH.


Assuntos
Neoplasias dos Ductos Biliares , Colangiocarcinoma , Humanos , Pessoa de Meia-Idade , Idoso , Neoplasias dos Ductos Biliares/patologia , Estudos Retrospectivos , Colangiocarcinoma/patologia , Hepatectomia , Prognóstico , Ductos Biliares Intra-Hepáticos/cirurgia , Ductos Biliares Intra-Hepáticos/patologia
13.
Front Oncol ; 12: 1015308, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36452508

RESUMO

Objective: Colorectal cancer (CRC) is a common type of malignant tumor of the digestive tract. Tumor mutation burden (TMB) is a potential prognostic indicator of numerous malignant tumors. This study investigated the prognostic value of TMB in CRC. Methods: This study analyzed the clinical and somatic mutation data of patients with CRC from the Memorial Sloan Kettering Cancer Center (MSKCC) and The Cancer Genome Atlas (TCGA) cohorts. The genetic landscape was visualized using the maftools package in R software. Survival curves were constructed using the Kaplan-Meier method, and Cox regression analysis was performed to confirm that TMB is an independent prognostic indicator. A nomogram was developed to construct the prognostic model, which was evaluated using the C-index, calibration curve, and decision curve analysis. Results: In patients with CRC, APC mutations indicated longer overall survival (OS), whereas KRAS mutations indicated shorter OS. For all included patients, there was no significant difference in the OS between the TMB-high and TMB-low groups. For patients with KRAS mutations, the OS in the TMB-high group was longer than that in the TMB-low group. Cox regression analysis showed that TMB was an independent prognostic factor in CRC patients with KRAS mutations. This explains the good accuracy of the nomogram prognostic model using TMB and indicates its good prospect in clinical applications. Conclusions: A high TMB indicates better prognosis in CRC patients with KRAS mutations, thus confirming the value of TMB in clinical applications.

14.
Polymers (Basel) ; 14(22)2022 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-36432999

RESUMO

The low fire safety performance (flame retardant and antistatic properties) of poly(methyl methacrylate) (PMMA) has severely limited practical applications. Here, a phosphorylated Zn-based metal-organic framework (ZIF-8-P) is employed as an effective flame retardant and antistatic agent to reduce the fire risk of PMMA. Encouragingly, the as-prepared PMMA/ZIF-8-P composite demonstrated not merely better mechanical properties (e.g., a rise of ca. 136.9% and 175.0% in the reduced modulus and hardness; a higher storage modulus), but also efficient fire safety properties (e.g., lower surface resistance; a decrease of ca. 73.1% in the peak heat release rate; a lower amount of total pyrolysis products), surpassing those of pure PMMA and a PMMA/ZIF-8 composite without phytic acid modification. Mechanism analysis is conducted to reveal the critical role of catalytic charring, char reinforcing, and the dilution of nonflammable gases from ZIF-8 additives during the combustion and pyrolysis process. Our study paves a promising way to achieve high performance PMMA composites.

15.
Front Surg ; 9: 1003948, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36325045

RESUMO

Background: Intrahepatic cholangiocarcinoma is a highly malignant and invasive cancer originating from biliary epithelial cells. The current study was designed to evaluate the feasibility, safety, and clinical outcomes of laparoscopic anatomical hepatectomy in patients with intrahepatic cholangiocarcinoma. Methods: After screening, 95 patients who underwent anatomical hepatectomy for intrahepatic cholangiocarcinoma at our center were enrolled and divided into two groups according to the surgical approach; the baseline characteristics, pathological findings, surgical outcomes, and long-term outcomes were compared. Moreover, univariate and multivariate analyses were performed to identify independent prognostic factors for overall survival (OS) and disease-free survival (DFS). Results: There were no significant differences in baseline characteristics or pathological findings between the two groups. Regarding short-term outcomes, the intraoperative blood loss, incision length, and length of postoperative hospital stay were more favorable in the laparoscopic anatomical hepatectomy group than the open anatomical hepatectomy group (P < 0.05). The two groups differed significantly in the extent of liver resection, with a lower lymph node dissection rate and lymph node yield in the laparoscopic anatomical hepatectomy group (P < 0.05). Furthermore, the postoperative complication rate was similar in the two groups (P > 0.05). The median postoperative follow-up times were 10.7 and 13.8 months in the laparoscopic anatomical hepatectomy and open anatomical hepatectomy groups, respectively. Regarding the long-term follow-up results, OS and DFS were similar in the two groups (P > 0.05). On multivariate analysis, the independent prognostic factors for OS were CA-199, CEA, HGB, tumor diameter, and T stage, and those for DFS were CA-199 (P < 0.05), and T stage (P < 0.05). Conclusion: laparoscopic anatomical hepatectomy for intrahepatic cholangiocarcinoma is safe and feasible when performed by experienced surgeons. Compared with open anatomical hepatectomy, laparoscopic anatomical hepatectomy provides better short-term outcomes and a comparable long-term prognosis.

16.
Polymers (Basel) ; 14(20)2022 Oct 13.
Artigo em Inglês | MEDLINE | ID: mdl-36297876

RESUMO

With the miniaturization and integration of electronic products, the heat dissipation efficiency of electronic equipment needs to be further improved. Notably, polymer materials are a choice for electronic equipment matrices because of their advantages of low cost and wide application availability. However, the thermal conductivity of polymers is insufficient to meet heat dissipation requirements, and their improvements remain challenging. For decades, as an efficient manufacturing technology, additive manufacturing has gradually attracted public attention, and researchers have also used this technology to produce new thermally conductive polymer materials. Here, we review the recent research progress of different 3D printing technologies in heat conduction and the thermal conduction mechanism of polymer matrix composites. Based on the classification of fillers, the research progress of thermally conductive materials prepared by fused filament fabrication (FFF) is discussed. It analyzes the internal relationship between FFF process parameters and the thermal conductivity of polymer matrix composites. Finally, this study summarizes the application and future development direction of thermally conductive composites by FFF.

17.
Polymers (Basel) ; 14(20)2022 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-36297898

RESUMO

The development of degradable plastic foams is in line with the current development concept of being pollution free and sustainable. Poly(lactic acid) (PLA) microporous foam with biodegradability, good heat resistance, biocompatibility, and mechanical properties can be successfully applied in cushioning packaging, heat insulation, noise reduction, filtration and adsorption, tissue engineering, and other fields. This paper summarizes and critically evaluates the latest research on preparing PLA microporous materials by supercritical carbon dioxide (scCO2) physical foaming since 2020. This paper first introduces the scCO2 foaming technologies for PLA and its composite foams, discusses the CO2-assisted foaming processes, and analyzes the effects of process parameters on PLA foaming. After that, the paper reviews the effects of modification methods such as chemical modification, filler filling, and mixing on the rheological and crystallization behaviors of PLA and provides an in-depth analysis of the mechanism of PLA foaming behavior to provide theoretical guidance for future research on PLA foaming. Lastly, the development and applications of PLA microporous materials based on scCO2 foaming technologies are prospected.

18.
Opt Express ; 30(16): 29015-29021, 2022 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-36299086

RESUMO

We present a high-power continuous-wave (CW) Tm:YAG single-crystal fiber (SCF) laser wing-pumped by laser diodes at 791 nm. A maximum output power of 63.3 W is achieved at ∼ 2.01 µm, corresponding to a slope efficiency of 34.2%. This is, to the best of our knowledge, the highest power obtained from the SCF laser in the 2 µm spectral range. In addition to the wing pumping scheme, the large surface-to-volume ratio of such fiber-geometry crystalline rod with diffusion-bonded undoped YAG end caps are benefited for the spatial uniform distribution of pump intensity and thermal load, and thus improving the power scalability.

19.
Comput Math Methods Med ; 2022: 9052751, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35991147

RESUMO

Medical 3D image reconstruction is an important image processing step in medical image analysis. How to speed up the speed while improving the accuracy in 3D reconstruction is an important issue. To solve this problem, this paper proposes a 3D reconstruction method based on image feature point matching. By improving SIFT, the initial matching of feature points is realized by using the neighborhood voting method, and then the initial matching points are optimized by the improved RANSAC algorithm, and a new SFM reconstruction method is obtained. The experimental results show that the feature matching rate of this algorithm on Fountain data is 95.42% and the matching speed is 4.751 s. It can be seen that this algorithm can shorten the reconstruction time and obtain sparse point clouds with more reasonable distribution and better reconstruction effect.


Assuntos
Algoritmos , Imageamento Tridimensional , Humanos , Processamento de Imagem Assistida por Computador/métodos , Imageamento Tridimensional/métodos
20.
ACS Appl Mater Interfaces ; 14(19): 22615-22625, 2022 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-35506598

RESUMO

This research aims to develop a practical, scalable, and highly conductive flexible 3D printed piezoresistive sensor with low filler content. Here, we introduced a fused deposition modeling 3D printing combined in situ spray-coating technique to develop a conductive sensor in a single shot. The graphene suspension is sprayed over each layer during the 3D printing of the sensor, which helps develop a conductive network on the surface and at the interface of the printed system. Graphene deposited on the overall surface is often affected by nanoparticle delamination and loses its function over time. To avoid this, the prepared samples are subjected to foaming. The foaming process created a low-mass-density sensor by forming a microcellular structure, and the surface-deposited graphene is embedded well on the TPU surface. The method followed in this work reveals a stable and connected conduction path with excellent electrical resistance and resistance against harsh conditions (exposure to organic solvents). Besides, the compression sensor withstood its sensitivity over a severe compressive strain of 80% and showed a GF of 1.82 and a sensitivity of 2.316 kPa-1. The conductive network path varied based on the infill pattern, affecting its electrical sensitivity. The wiggle pattern shows good resistance; under stretching, the pattern generated a higher current and showed a delayed conductive path disconnection than other patterns. Thus, the embedded graphene/TPU conductive sensors show good stability and promising sensitivity. Furthermore, the developed sensor is used to monitor human motion and actions.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA