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  • 1
    Online Resource
    Online Resource
    Flexural Properties, Impact Strength, and Hardness of Nanodiamond-Modified PMMA Denture Base Resin
    Hindawi Limited ; 2022
    In:  International Journal of Biomaterials Vol. 2022 ( 2022-7-9), p. 1-10
    Details
    In: International Journal of Biomaterials, Hindawi Limited, Vol. 2022 ( 2022-7-9), p. 1-10
    Abstract: Purpose. Investigate the effect of low nanodiamond (ND) addition and autoclave polymerization on the flexural strength, impact strength, and hardness of polymethylmethacrylate (PMMA) denture base. Methods. A total of 240 heat polymerized PMMA were fabricated with low ND concentrations of 0.1%, 0.25%, and 0.5%, and unmodified as control. The specimens were divided equally into group I: conventionally polymerized PMMA by water bath and group II: polymerized by the autoclave. The impact strength, flexural strength, and elastic modulus were tested using the Charpy-type impact-testing machine and three-point bending test, respectively. A scanning electron microscope (SEM) was used to analyze the fractured surfaces. Surface hardness was measured by a hardness tester with a Vickers diamond. The bonding and interaction between the PMMA and ND particles were analyzed by the Fourier-transform infrared (FTIR) spectroscope. ANOVA and post hoc Tukey test were used for data analysis (α = 0.05). Results. ND addition significantly increased the flexural strength of groups I and II ( p 〈 0.001 , p = 0.003 ); it was highest (128.8 MPa) at 0.25% ND concentration for group I and at 0.1% for group II. Elastic modulus increased at 0.1% ND for both groups ( p = 0.004 , p = 0.373 ), but the increase was statistically significant for group I only. Impact strength showed no significant change with the addition of ND in groups I and II ( p = 0.227 , p = 0.273 ), as well as surface hardness in group I ( p = 0.143 ). Hardness decreased significantly with 0.25%ND in group II. Conclusion. The addition of ND at low concentration increased the elastic modulus and flexural strength of conventionally and autoclave polymerized denture base resin. Autoclave polymerization significantly increased the flexural strength, impact strength, and hardness of unmodified PMMA and hardness of 0.5% ND group.
    Type of Medium: Online Resource
    ISSN: 1687-8795 , 1687-8787
    URL: Article
    DOI: 10.1155/2022/6583084
    Language: English
    Publisher: Hindawi Limited
    Publication Date: 2022
    detail.hit.zdb_id: 2494344-7
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  • 2
    Online Resource
    Online Resource
    The Effect of Changing Fellowship Interview Format on Candidate Ranking Variabilities: The COVID-19 Experience
    Hindawi Limited ; 2022
    In:  Journal of Ophthalmology Vol. 2022 ( 2022-4-13), p. 1-6
    Details
    In: Journal of Ophthalmology, Hindawi Limited, Vol. 2022 ( 2022-4-13), p. 1-6
    Abstract: Purpose. This study investigated the effect of interview format changes (in-person to virtual, one-to-one to multiple-to-one) necessitated by the COVID-19 travel restrictions on preliminary fellowship candidate ranking variabilities. Design. Cross-sectional observational study. Method. In 2018 and 2019, the glaucoma fellowship interviews were conducted in-person in a one-to-one format, whereas in 2020, interviews were virtual and in a multiple (interviewers)-to-one (candidate) format. We compared ranking ranges of interviewers within the same virtual room (WSR) and not within the same virtual room (NWSR) to assess the effect of WSR versus NWSR on ranking variabilities. We also compared ranking categories (“accept,” “alternate,” and “pass”) agreements between 2018, 2019, and 2020 to assess the effect of virtual versus in-person interviews on ranking variabilities. Results. NWSR and WSR mean rankings differed by 1.33 (95% confidence interval difference 0.61 to 2.04, p = 0.0003), with WSR interviewers having less variability than NWSR pairs. The variability between 2018/2019 (in-person interviews) and 2020 (virtual interviews) showed no differences between in-person and virtual interviews (weighted Kappa statistic 0.086 for 2018, 0.158 for 2019, and 0.101 for 2020; p  〈  0.05 for all years). The overall least attractive candidate has the lowest variability; the most attractive candidate has the second lowest variability. Conclusion. Grouping interviewers WSR during the interview decreased ranking variabilities compared to NWSR, while a change from in-person to virtual interview format did not increase the ranking variabilities. This suggests that the decreased nonverbal interactions in virtual interviews do not decrease interviewers’ perceptions as applied to preliminary rankings.
    Type of Medium: Online Resource
    ISSN: 2090-0058 , 2090-004X
    URL: Article
    DOI: 10.1155/2022/7402079
    Language: English
    Publisher: Hindawi Limited
    Publication Date: 2022
    detail.hit.zdb_id: 2546525-9
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  • 3
    Online Resource
    Online Resource
    The Effect of Patient Characteristics and Sleep Quality on Visual Field Performance Reliability
    Hindawi Limited ; 2018
    In:  Journal of Ophthalmology Vol. 2018 ( 2018), p. 1-4
    Details
    In: Journal of Ophthalmology, Hindawi Limited, Vol. 2018 ( 2018), p. 1-4
    Abstract: Purpose . To investigate the association of automated visual field (VF) reliability indices (false positive [FP], false negative [FN] , and fixation loss [FL]) and sleep quality, VF experience, and age. Methods . Prospective, cross-sectional study. Adult patients (age ≥ 18 years) completing automated VF testing were invited to participate. Baseline participant characteristics were obtained, and all participants were asked to complete the Pittsburgh Sleep Quality Index (PSQI) questionnaire. Nonparametric Spearman correlations and logistical regression models were performed. Results . 63 patients were enrolled. Lower PSQI score was correlated with higher percentage (%) FL in the right eye ( p = 0.03 ). Fewer prior VF was significantly correlated with higher %FP in the right eye ( p = 0.008 ). Older age was significantly correlated with higher %FN in the left eye ( p = 0.01 ). Greater mean deviation (MD) and pattern standard deviation (PSD) were strongly correlated with higher %FN in the right ( p = 0.02 and 0.002, resp.) and left eyes ( p = 0.01 and 0.02, resp.). Conclusion . In this prospective, cross-sectional study, worse MD and PSD are strongly correlated with increased FN in both eyes. Increased FN in the left eye associated with older age might be attributable to test fatigue. Worse sleep quality is associated with decreased FL in the right eye.
    Type of Medium: Online Resource
    ISSN: 2090-004X , 2090-0058
    URL: Article
    DOI: 10.1155/2018/2731260
    Language: English
    Publisher: Hindawi Limited
    Publication Date: 2018
    detail.hit.zdb_id: 2546525-9
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  • 4
    Online Resource
    Online Resource
    Investigation of CO2 Extract of Portulaca oleracea for Antioxidant Activity from Raw Material Cultivated in Kazakhstan
    Hindawi Limited ; 2022
    In:  International Journal of Biomaterials Vol. 2022 ( 2022-4-22), p. 1-11
    Details
    In: International Journal of Biomaterials, Hindawi Limited, Vol. 2022 ( 2022-4-22), p. 1-11
    Abstract: Medicinal plants remain as an important resource in the fight against many diseases, especially in developing countries. Antioxidants are substances capable of delaying, retarding, and preventing the oxidation of lipids or substances that delay or prevent free radical reactions during lipid oxidation. Natural antioxidants such as ascorbic acid, tocopherol, phenolic compounds, and flavonoids are a safe alternative to chemical antioxidants. In present work, results of antioxidant activity of raw materials from the cultivated plant Portulaca oleracea are presented. The extraction time was optimized to 780 minutes; the yield of extractive substances was 1.25% in the production of CO2 extract under subcritical conditions. For the first time, the antioxidant activity of Portulaca oleracea CO2 extract was determined by the amperometric method. Gas chromatography-mass spectrometry (GC-MS) chemical analysis of Portulaca oleracea CO2 extract dissolved in hexane revealed 37 components, including a complex mixture of aldehydes, alkanes, alkenes, esters, diterpenes, steroids, vitamin E, and carbohydrates. The investigation results showed that the Portulaca oleracea CO2 extract was promising for pharmaceutical, cosmetic, and food industries and had great potential for the prevention and treatment of diseases caused by oxidative stress.
    Type of Medium: Online Resource
    ISSN: 1687-8795 , 1687-8787
    URL: Article
    DOI: 10.1155/2022/6478977
    Language: English
    Publisher: Hindawi Limited
    Publication Date: 2022
    detail.hit.zdb_id: 2494344-7
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