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1.
Gastroenterology ; 165(1): 133-148.e17, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-36907523

RESUMO

BACKGROUND & AIMS: Pancreatic ductal adenocarcinoma (PDA), with its highly metastatic propensity, is one of the most lethal subtypes of pancreatic cancer. Although recent large-scale transcriptomic studies have demonstrated that heterogeneous gene expressions play an essential role in determining molecular phenotypes of PDA, biological cues for and consequences of distinct transcriptional programs remain unclear. METHODS: We developed an experimental model that enforces the transition of PDA cells toward a basal-like subtype. We combined epigenome and transcriptome analyses with extensive in vitro and in vivo evaluations of tumorigenicity to demonstrate the validity of basal-like subtype differentiation in association with endothelial-like enhancer landscapes via TEA domain transcription factor 2 (TEAD2). Finally, we used loss-of-function experiments to investigate the importance of TEAD2 in regulating reprogrammed enhancer landscape and metastasis in basal-like PDA cells. RESULTS: Aggressive characteristics of the basal-like subtype are faithfully recapitulated in vitro and in vivo, demonstrating the physiological relevance of our model. Further, we showed that basal-like subtype PDA cells acquire a TEAD2-dependent proangiogenic enhancer landscape. Genetic and pharmacologic inhibitions of TEAD2 in basal-like subtype PDA cells impair their proangiogenic phenotypes in vitro and cancer progression in vivo. Last, we identify CD109 as a critical TEAD2 downstream mediator that maintains constitutively activated JAK-STAT signaling in basal-like PDA cells and tumors. CONCLUSIONS: Our findings implicate a TEAD2-CD109-JAK/STAT axis in the basal-like differentiated pancreatic cancer cells and as a potential therapeutic vulnerability.


Assuntos
Carcinoma Ductal Pancreático , Neoplasias Pancreáticas , Humanos , Neoplasias Pancreáticas/patologia , Carcinoma Ductal Pancreático/patologia , Pâncreas/patologia , Diferenciação Celular , Regulação Neoplásica da Expressão Gênica , Fatores de Transcrição de Domínio TEA , Neoplasias Pancreáticas
2.
Vascular ; : 17085381241254566, 2024 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-38752555

RESUMO

PURPOSE: Arteriovenous fistula (AVF) is the preferred treatment for long-term hemodialysis patients to allow reliable vascular access. Arteriovenous graft (AVG) is monitored using Doppler sonography to check a vessel's condition and predict complications such as steal syndrome. In this study, we developed an analysis algorithm and method to quantify steal syndrome using Doppler sonography. METHODS: Doppler sonography was used to determine the pattern of anterograde and retrograde flow. The ratio of blood volumes was calculated with a vision analysis software. First, performance of the developed algorithm was validated by comparing it with commercial Doppler sonography data. Doppler sonography was performed for an artificial vessel to analyze the steal flow. RESULTS: A total of 58 patients with steal flow were enrolled in this study. Of these patients, 23 did not have a difference in fingertip temperature between both sides. The median difference in temperature of 35 patients was 0.8°C (range, 0.3-1.9°C). The ratio of retrograde flow volume/antegrade flow volume in patients with the presence of temperature difference was significantly higher compared to that in patients without the temperature difference (p < .001). The ROC curve for the difference in flow volume had an AUC of 0.770. The optimal cutoff of difference in the flow volume between the two groups was 0.24 (sensitivity of 91.4 % and specificity of 52.2%). The flow volume difference was significantly positively correlated to temperature difference (r = 0.487, p < .003). CONCLUSION: Our algorithm could measure steal flow volume of a bidirectional waveform by antegrade arterial flow and retrograde reversal flow.

3.
BMC Nephrol ; 24(1): 31, 2023 02 09.
Artigo em Inglês | MEDLINE | ID: mdl-36759777

RESUMO

PURPOSE: One of the rare life-threatening fungal infections is pneumocystis pneumonia (PCP). Immunocompromised patients are the main vulnerable population. We investigate the risk factors associated with the development of severe PCP infection with acute respiratory failure after kidney transplantation. MATERIALS AND METHODS: This is a retrospective, single-center, case-control study. PCP patients who are kidney transplant recipients and required high-flow oxygen support or mechanical ventilation between March 2009 and February 2017 were included in the study. The comparison was conducted between the non-severe and severe PCP groups. To identify associated risk factors, we performed univariate and multivariate logistic regression. RESULTS: Among the total 2,330 kidney transplant recipients, 50 patients (2.1%) were diagnosed with PCP. Of these, 27 patients (54.0%) had severe PCP and 7 patients (14.0%) died, all of them were severe PCP patients. In the severe PCP group, the time from transplantation to PCP diagnosis (23.4 ± 24.9 months vs. 13.7 ± 9.9 months, p = 0.090) was insignificantly faster than in the non-severe PCP group. According to multiple logistic regression analysis, the significant risk factors associated with severe PCP were as follows, age (odds ratios (OR) 1.07; 95% confidence intervals (CI): 1.01-1.13; p = 0.027), time from transplantation to PCP diagnosis (odds ratios (OR) 0.92; 95% confidence intervals (CI): 0.86-0.99; p = 0.024), lymphopenia (OR 6.48; 95% CI: 1.05-40.09; p = 0.044), and history of acute rejection within 1 year (OR 8.28; 95% CI: 1.29-53.20; p = 0.026). CONCLUSION: Patients who have lymphopenia at the time of hospital admission or have been recently treated with acute rejection are more likely to progress to severe PCP, requiring intensive monitoring and aggressive treatment.


Assuntos
Transplante de Rim , Linfopenia , Pneumocystis carinii , Pneumonia por Pneumocystis , Insuficiência Respiratória , Humanos , Pneumonia por Pneumocystis/etiologia , Transplante de Rim/efeitos adversos , Estudos Retrospectivos , Estudos de Casos e Controles , Fatores de Risco , Transplantados , Linfopenia/epidemiologia , Linfopenia/complicações , Insuficiência Respiratória/epidemiologia , Insuficiência Respiratória/complicações
4.
Asia Pac J Clin Nutr ; 32(3): 321-329, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37789652

RESUMO

BACKGROUND AND OBJECTIVES: Patients with acute kidney injury requiring continuous renal replacement therapy are at high risk of malnutrition. Nutritional support is an important part of treatment for patients with critical illness admitted to the intensive care unit. We aimed to investigate the status of nutritional provision and the effects of nutritional support on clinical outcomes. METHODS AND STUDY DESIGN: Our institution's medical records (from January 1, 2020, to December 31, 2021) were analyzed in this retrospective cohort study. We included 43 patients aged >18 years who received continuous renal replacement therapy for acute kidney injury in the surgical intensive care unit. RESULTS: The demographic characteristics were similar between the survivor and non-survivor groups. The protein supply per body weight (0.88 ± 0.37 g/kg vs. 0.47 ± 0.53 g/kg, p = 0.029) and the proportion of patients who met the target protein level (58.9 ± 24.9% vs. 30.8 ± 34.9%, p = 0.022) were significantly higher in the survivor group. Approximately 79.1% of the patients had a high malnutrition risk with a modified Nutrition Risk in the Critically Ill score of ≥5. The lengths of hospital and intensive care unit stays were longer in the high nutritional risk group compared with that in the low nutritional risk group, but the result was not significant. CONCLUSIONS: The nutritional amount provided in patients with critical illness is significantly lesser than the recommended amount. Ensuring proper nutritional support can improve the clinical outcomes.


Assuntos
Injúria Renal Aguda , Terapia de Substituição Renal Contínua , Desnutrição , Humanos , Estudos Retrospectivos , Estado Terminal/terapia , Unidades de Terapia Intensiva , Apoio Nutricional , Injúria Renal Aguda/terapia , Cuidados Críticos , Terapia de Substituição Renal
5.
Biomacromolecules ; 23(9): 3582-3592, 2022 09 12.
Artigo em Inglês | MEDLINE | ID: mdl-35949062

RESUMO

The combination of hyperthermia and chemotherapy has attracted significant attention in local cancer treatment following surgical resection. Pyrrole is a potent photothermal agent that can induce a temperature rise at different concentrations in the surrounding medium by absorbing near-infrared radiation (NIR). In this study, poly(ε-caprolactone) (PCL) and poly (d,l-lactic-co-glycolic acid) (PLGA) were used to make nanofibers using the electrospinning process. Then, pyrrole in different concentrations of (0.2, 0.4, and 0.6) M was attached to the surface of PCL-PLGA fiber mats by in situ polymerization, which was confirmed by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD) analysis. A concentration-dependent local temperature rise was observed using a FLIR camera under near-infrared (NIR) laser irradiation. For the hyperthermia effect, pyrrole concentration (0.06 M) was used for in vitro drug release studies and cell viability assays because under NIR irradiation (2 W/cm2, 3 min), it increased the local temperature to around 45 °C. In vitro drug release studies confirmed that NIR irradiation increased the diffusion rate of doxorubicin (DOX) by increasing the environmental temperature above the glass transition temperature of PLGA. In vitro cytotoxicity experiments further confirmed that PCL-PLGA-DOX/PPy fiber mats showed an enhanced inhibitory effect against CT26 and MCF7 cells by the combination of hyperthermia and chemotherapy.


Assuntos
Hipertermia Induzida , Nanofibras , Neoplasias , Doxorrubicina , Glicolatos , Glicóis , Humanos , Ácido Láctico , Nanofibras/química , Neoplasias/tratamento farmacológico , Fototerapia/métodos , Poliésteres , Pirróis/química , Espectroscopia de Infravermelho com Transformada de Fourier
6.
Biomacromolecules ; 23(12): 4995-5006, 2022 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-36367817

RESUMO

Various methods have been studied to make a regenerated silk fibroin solution. However, most of them take too much time and effort to liquefy. Here, we report that a regenerated silk fibroin solution could be prepared within seconds through acid proteolysis for the first time. The solubilized fibroin could be applied to advanced tissue engineering. Our method shortened the production time to one day (more than 10 times) compared to the general fibroin solution preparation method. It was confirmed that the initial protein affinity nearly doubled from 0.028 to 0.076 µg·mm-2 in FF(ac) compared to FF(aq). A fibroin nanofiber layer having a volumetric hierarchical structure was prepared by electrospinning an acid-proteolyzed fibroin solution, followed by gas foaming. In vitro results of cell adhesion and proliferation capacity of the gas-foamed scaffold were not significantly different compared to the two-dimensional (2D) fibroin nanofiber membrane, overcoming the limitations of volumetric nanofiber scaffolds. We are confident that our research will greatly contribute to the development of regenerative engineering using other proteins.


Assuntos
Fibroínas , Nanofibras , Fibroínas/química , Engenharia Tecidual/métodos , Alicerces Teciduais/química , Nanofibras/química , Adesão Celular , Seda
7.
BMC Infect Dis ; 22(1): 953, 2022 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-36536308

RESUMO

BACKGROUND: Sepsis is the most common cause of death in hospitals, and intra-abdominal infection (IAI) accounts for a large portion of the causes of sepsis. We investigated the clinical outcomes and factors influencing mortality of patients with sepsis due to IAI. METHODS: This post-hoc analysis of a prospective cohort study included 2126 patients with sepsis who visited 16 tertiary care hospitals in Korea (September 2019-February 2020). The analysis included 219 patients aged > 19 years who were admitted to intensive care units owing to sepsis caused by IAI. RESULTS: The incidence of septic shock was 47% and was significantly higher in the non-survivor group (58.7% vs 42.3%, p = 0.028). The overall 28-day mortality was 28.8%. In multivariable logistic regression, after adjusting for age, sex, Charlson Comorbidity Index, and lactic acid, only coagulation dysfunction (odds ratio: 2.78 [1.47-5.23], p = 0.001) was independently associated, and after adjusting for each risk factor, only simplified acute physiology score III (SAPS 3) (p < 0.001) and continuous renal replacement therapy (CRRT) (p < 0.001) were independently associated with higher 28-day mortality. CONCLUSIONS: The SAPS 3 score and acute kidney injury with CRRT were independently associated with increased 28-day mortality. Additional support may be needed in patients with coagulopathy than in those with other organ dysfunctions due to IAI because patients with coagulopathy had worse prognosis.


Assuntos
Infecções Intra-Abdominais , Sepse , Humanos , Prognóstico , Estudos Prospectivos , Unidades de Terapia Intensiva , Infecções Intra-Abdominais/complicações , República da Coreia , Estudos Retrospectivos
8.
Environ Res ; 210: 112864, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35149108

RESUMO

This study was aimed on the eco-friendly synthesis of silver nanoparticles (AgNPs), reduced graphene oxide (rGO) and AgNPs decorated rGO (rGO/AgNPs) nanocomposite and appraisal of their bioactivities and toxicity. As-prepared nanomaterials were established through high resolution X-ray diffraction (HR-XRD), high resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, UV-Vis. spectroscopy and Fourier transform infrared spectroscopy (FT-IR). In this study, leaves extract, graphene oxide (GO) and rGO did not show antibacterial and anticancer activities; no significant embryo toxicity was recorded. On the other hand, AgNPs displayed good antibacterial and anticancer activities; however, higher toxic effects were observed even at the lowest test concentration (0.7 µg/ml). In case of rGO/AgNPs nanocomposite, significant antibacterial activity together with low cytotoxicity was noticed. Interestingly, the embryo toxicity of AgNPs was significantly reduced by rGO, implying the biocompatible nature of as-synthesized nanocomposite. Taken together, these results clearly suggest that rGO/AgNPs nano hybrid composite could be developed as the promising biomaterial for future biomedical applications.


Assuntos
Nanopartículas Metálicas , Nanocompostos , Antibacterianos/toxicidade , Grafite , Nanopartículas Metálicas/química , Nanopartículas Metálicas/toxicidade , Nanocompostos/química , Prata/química , Prata/toxicidade , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X
9.
Anal Chem ; 93(2): 801-811, 2021 01 19.
Artigo em Inglês | MEDLINE | ID: mdl-33284604

RESUMO

An easily accessible colorimetric and fluorescence probe 4-((3-chloro-1,4-dioxo-1,4-dihydronaphthalen-2-yl)amino)benzenesulfonamide (4CBS) was successfully developed for the selective and sensitive detection of Sn2+ in an aqueous solution. The sensing mechanism involves reduction of -C═O into -C-OH groups in 4CBS upon the addition of Sn2+, which initiates the fluorescence turn-on mode. A better linear relationship was achieved between fluorescence intensity and Sn2+ concentration in the range of 0-62.5 µM, with a detection limit (LOD) of 0.115 µM. The binding mechanism of 4CBS for Sn2+ was confirmed by Fourier transform infrared analysis, NMR titrations, and mass (electrospray ionization) spectral analysis. Likewise, the proposed sensing mechanism was supported by quantum chemical calculations. Moreover, bioimaging studies demonstrated that the chemosensing probe 4CBS is an effective fluorescent marker for the detection of Sn2+ in living cells and zebrafish. Significantly, 4CBS was able to discriminate between Sn2+ in human cancer cells and Sn2+ in normal live cells.


Assuntos
Colorimetria/métodos , Sulfonamidas/síntese química , Estanho/química , Animais , Linhagem Celular , Técnicas Eletroquímicas , Humanos , Larva , Camundongos , Modelos Moleculares , Estrutura Molecular , Imagem Óptica , Sensibilidade e Especificidade , Sulfonamidas/química , Água , Peixe-Zebra
10.
Nanotechnology ; 33(5)2021 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-34673562

RESUMO

In this work, we synthesized a monolayer of graphene and hexagonal boron nitride (hBN) using chemical vapor deposition. The physicochemical and electrochemical properties of the materials were evaluated to determine their morphology. High-purity materials and their atomic-scale coating on copper (Cu) foil were employed to prevent fast degradation rate. The hexagonal two-dimensional (2D) atomic structures of the as-prepared materials were assessed to derive their best anti-corrosion behavior. The material prepared under optimized conditions included edge-defect-free graphene nanosheets (∼0.0034µm2) and hBN (∼0.0038µm2) per unit area of 1µm2. The coating of each material on the Cu surface significantly reduced the corrosion rate, which was âˆ¼2.44 × 10-2/year and 6.57 × 10-3/year for graphene/Cu and hBN/Cu, respectively. Importantly, the corrosion rate of Cu was approximately 3-fold lower after coating with hBN relative to that of graphene/Cu. This approach suggests that the surface coating of Cu using cost-effective, eco-friendly, and the most abundant materials in nature is of interest for developing marine anti-corrosion micro-electronic devices and achieving surface modification of pure metals in industrial applications.

11.
Nanomedicine ; 30: 102306, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32992018

RESUMO

The major challenge of commercially available vascular substitutes comes from their limitations in terms of hydrophobic surface, which is hostile to cell growth. To date, tissue-engineered and synthetic grafts have not translated well to clinical trials when looking at small diameters. We conceptualized a cell-free structurally reinforced biodegradable vascular graft recapitulating the anisotropic feature of a native blood vessel. The nanofibrous scaffold is designed in such a way that it will gradually degrade systematically to yield a neo-vessel, facilitated by an immobilized bioactive molecule-vascular endothelial growth factor (VEGF). The nano-topographic cue of the device is capable of direct host cell infiltration. We evaluated the burst pressure, histology, hemocompatibility, compression test, and mechanical analysis of the new graft. The graft implanted into the carotid artery of a porcine model demonstrated a good patency rate as early as two week post-implantation. This graft reinforced design approach when employed in vascular tissue engineering might strongly influencing regenerative medicine.


Assuntos
Prótese Vascular , Impressão Tridimensional , Fator A de Crescimento do Endotélio Vascular/administração & dosagem , Animais , Artérias Carótidas/cirurgia , Modelos Animais , Medicina Regenerativa , Suínos , Engenharia Tecidual
12.
Int J Mol Sci ; 21(9)2020 Apr 27.
Artigo em Inglês | MEDLINE | ID: mdl-32349395

RESUMO

Genetic variability can modulate individual drug responses. A significant portion of pharmacogenetic variants reside in the noncoding genome yet it is unclear if the noncoding variants directly influence protein function and expression or are present on a haplotype including a functionally relevant genetic variation (synthetic association). Gene-wise variant burden (GVB) is a gene-level measure of deleteriousness, reflecting the cumulative effects of deleterious coding variants, predicted in silico. To test potential associations between noncoding and coding pharmacogenetic variants, we computed a drug-level GVB for 5099 drugs from DrugBank for 2504 genomes of the 1000 Genomes Project and evaluated the correlation between the long-known noncoding variant-drug associations in PharmGKB, with functionally relevant rare and common coding variants aggregated into GVBs. We obtained the area under the receiver operating characteristics curve (AUC) by comparing the drug-level GVB ranks against the corresponding pharmacogenetic variants-drug associations in PharmGKB. We obtained high overall AUCs (0.710 ± 0.022-0.734 ± 0.018) for six different methods (i.e., SIFT, MutationTaster, Polyphen-2 HVAR, Polyphen-2 HDIV, phyloP, and GERP++), and further improved the ethnicity-specific validations (0.759 ± 0.066-0.791 ± 0.078). These results suggest that a significant portion of the long-known noncoding variant-drug associations can be explained as synthetic associations with rare and common coding variants burden of the corresponding pharmacogenes.


Assuntos
Farmacogenética , Variantes Farmacogenômicos , RNA não Traduzido , Biomarcadores , Bases de Dados Genéticas , Bases de Dados de Produtos Farmacêuticos , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Farmacogenética/métodos , Curva ROC , Fluxo de Trabalho
13.
J Nanosci Nanotechnol ; 19(4): 2228-2231, 2019 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-30486973

RESUMO

We have studied the technique for efficient prolong the shelf-life of fruit. To prolong the shelf-life of fruit, one of the most important factor is the concentration of oxygen (O2) and carbon dioxide (CO2) produced by the fruits inside the packaging. Therefore, to create the right environment, it recommended creating pores which O2 and CO2 can be exchanged. We utilize electrospinning technique for easy electrohydrodynamic fabrication of nanofibers by electric force to fabricate nano-sized fibers with high porosity. Additionally, use of essential oil is very appropriate to reduce postharvest disease cause of their antibacterial and like-pesticide properties. In this study, we fabricated different structural packaging types using nanofibers and essential oil to compare the efficacy. After that, we observed the percentage of corruption is significantly reduced by using peach as a kind of fruits. These packaging techniques will overcome the limitation of fruits life with postharvest disease not only field of fruit packaging techniques.


Assuntos
Nanofibras , Óleos Voláteis , Dióxido de Carbono , Embalagem de Alimentos , Frutas
14.
J Nanosci Nanotechnol ; 19(2): 697-700, 2019 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-30360144

RESUMO

A new nano air filter for fine dust filtration with antibacterial and volatile organic compounds (VOCs) adsorption properties was fabricated using a bottom-up, high-speed electrospinning system. To optimize production, polyurethane fibers were electrospun at various voltages on polypropylene nonwoven fabrics, and results show that fiber diameter decreased as voltage increased. Silver nanoparticles (AgNPs) and Activated Carbon (AC) were used as antimicrobials and VOC-reducing agents. FTIR, SEM, and EDS were performed to analyze the resulting filter fabricated by electrospinning. FTIR and EDS results show that the AgNPs and activated carbon added to the PU fibers were successfully integrated into the PP nonwoven fabric.


Assuntos
Anti-Infecciosos , Nanopartículas Metálicas , Compostos Orgânicos Voláteis , Adsorção , Anti-Infecciosos/farmacologia , Prata/farmacologia
15.
J Nanosci Nanotechnol ; 19(4): 2232-2235, 2019 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-30486974

RESUMO

We have successfully extracted cellulose nanocrystals (CNCs) from seaweed by removing unwanted materials via our modified process. The prepared CNCs were mixed with two biocompatible polymers (polyethylene oxide (PEO)/Eudragit S100). We used the most popular electrospinning method to fabricate a micro/nano-net membrane. The formation of nano-webs between fundamental micro/nanofibers was observed via SEM and TEM, according to the mixing ratio of the solution (PEO:Eudragit: 1:1, 2:1, 3:1 wt:wt%) with 0, 5, 10% CNCs per polymer weight. We found the optimal condition to fabricate nano-net in the membrane and expect it to be applicable for wound healing, tissue engineering, and various filter applications.


Assuntos
Nanofibras , Nanopartículas , Alga Marinha , Celulose , Engenharia Tecidual
16.
J Nanosci Nanotechnol ; 19(4): 2399-2403, 2019 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-30487008

RESUMO

There is a large margin between the mechanical properties and morphology of electrospun fibers required in each area. The produced fibers show a large difference depending on the external environment such as temperature, humidity, and season even in optimum concentration and same electrospinning set-up. The properties of polymer solution among the parameters are the largest determinant of the mechanical strength and diameter of electrospun fibers. Herein, the accurate predicting system in advance to electrospinning is required. In this study, we conduct a comparative study on the viscosity (measured by Brookfield rheometer) and the transient mass change and evaporation speed by our lab-made QCN in order to establish a predicting system for the quality of fiber. It was possible to measure the change of mass of the polymer solution in real-time using the lab-made QCN as well as calculating the volatility, the evaporation time of the polymer solution. The volatility of the polymer solution has a significant impact on the quality of the electrospun fiber including the diameter, uniformity, and surface topography. We compare the mass changes, viscosimetric viscosities, and the quality of corresponding fiber, and reveal the potential of QCN as a tool predicting pre-electrospinning fibers.

17.
Sensors (Basel) ; 19(6)2019 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-30909427

RESUMO

In this study, a time-dependent corrosion depth estimation method using atmospheric corrosion monitor (ACM) sensor data to evaluate time-dependent corrosion behaviors is proposed. For the time-dependent corrosion depth estimation of uncoated carbon steel and weathering steel, acceleration corrosion tests were conducted in salt-spray corrosion environments and evaluated with a corrosion damage estimation method using ACM sensing data and corrosion loss data of the tested steel specimens. To estimate the time-dependent corrosion depth using corrosion current by an ACM sensor, the relationship between the mean corrosion depth calculated from the weight loss method and the corrosion current was evaluated. The mean corrosion depth was estimated by calculating the corrosion current and evaluating the relationship between the mean corrosion depth and corrosion current during the expected period. From the test and estimation results, the corrosion current demonstrated a good linear correlation with the mean corrosion depth of carbon steel and weathering. The calculated mean corrosion depth is nearly the same as that of the tested specimen, which can be well used to estimate corrosion rate for the uncoated carbon steel and weathering steel.

18.
Sensors (Basel) ; 19(9)2019 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-31085985

RESUMO

Designing a piezoelectric energy harvester (PEH) with high power density and high fatigue resistance is essential for the successful replacement of the currently using batteries in structural health monitoring (SHM) systems. Among the various designs, the PEH comprising of a cantilever structure as a passive layer and piezoelectric single crystal-based fiber composites (SFC) as an active layer showed excellent performance due to its high electromechanical properties and dynamic flexibilities that are suitable for low frequency vibrations. In the present study, an effort was made to investigate the reliable performance of hard and soft SFC based PEHs. The base acceleration of both PEHs is held at 7 m/s2 and the frequency of excitation is tuned to their resonant frequency (fr) and then the output power (Prms) is monitored for 107 fatigue cycles. The effect of fatigue cycles on the output voltage, vibration displacement, dielectric, and ferroelectric properties of PEHs was analyzed. It was noticed that fatigue-induced performance degradation is more prominent in soft SFC-based PEH (SS-PEH) than in hard SFC-based PEH (HS-PEH). The HS-PEH showed a slight degradation in the output power due to a shift in fr, however, no degradation in the maximum power was noticed, in fact, dielectric and ferroelectric properties were improved even after 107 vibration cycles. In this context, the present study provides a pathway to consider the fatigue life of piezoelectric material for the designing of PEH to be used at resonant conditions for long-term operation.

19.
J Nanosci Nanotechnol ; 18(2): 1123-1126, 2018 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-29448543

RESUMO

We have investigated the effect of flow rate on shear stress and in turn thrombus formation on a lab-on-a-chip with a microchannel that is suitable for cell culture and growth. Using a combination of Arduino UNO, Arduino Motor Shield, and a SERVO stepper motor, we created a pump system that closely mimics the in vivo conditions of the human body. With this system, we achieved continuous flow of blood and observed attached platelets at the bottom of the collagen coated microslide, confirming that with shear stress, thrombus formation increases.

20.
J Nanosci Nanotechnol ; 18(1): 529-537, 2018 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-29768878

RESUMO

Enhancing the biocompatibility profiles including cell attachment, growth, and viability and mechanical properties of designed synthetic scaffolds have an essential role in tissue engineering applications. Polymer blending is one of the most effective methods for providing new anticipated biomaterials for tissue scaffolds. Here, the blend solution of the different mass weight ratio of polycaprolactone (PCL) to human serum albumin (HSA) was subjected to fabricate nanocomposite spider-web-like membranes using electrospinning process. The physicochemical aspects of fabricated membranes had been characterized by a different state of techniques like that of scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analysis (TGA), contact angle meter and universal testing machine. FE-SEM images revealed that all PCL/HSA mats were composed of interlinked nano-nets along with conventional electrospun fibers while nano-nets were not found for pristine PCL mat. Moreover, composite membranes exhibited improved water absorbability, enhanced biodegradation compared to pristine PCL membrane and had much better mechanical properties (tensile strength increased by up to 3-fold, Young's modulus by 2-fold). The cell attachment and proliferation tests were carried by culturing Mc3T3-E1 (pre-osteoblasts) with the designated nanofibrous membranes. The hybrid nanofibers exhibited extraordinary support for the adhesion and proliferation of cells when compared to the pristine PCL membrane. These results indicate that the nano-nets supported PCL/HSA scaffolds can be promising for tissue engineering applications.


Assuntos
Materiais Biocompatíveis , Nanofibras , Engenharia Tecidual , Proliferação de Células , Humanos , Poliésteres , Espectroscopia de Infravermelho com Transformada de Fourier , Alicerces Teciduais
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