The acoustic response of a structure that contains a cavity filled with a loose granular material is analyzed. The inputs to the theory are the effective masses of each subsystem: that of the empty-cavity resonating structure and that of the granular medium within the cavity. This theory accurately predicts the frequencies, widths, and relative amplitudes of the various flexural mode resonances observed with rectangular bars, each having a cavity filled with loose tungsten granules. Inasmuch as the dominant mechanism for damping is due to adsorbed water at the grain-grain contacts, the significant effects of humidity on both the effective mass of the granular medium as well as on the response of the grain-loaded bars are monitored. Here, depending upon the humidity and the preparation protocol, it is possible to observe one, two, or three distinct resonances in a wide frequency range (1-5 kHz) over which the empty bar has but one resonance. These effects are understood in terms of the theoretical framework, which may simplify in terms of perturbation theories.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1121/1.3493465 | DOI Listing |
Cien Saude Colet
December 2024
Instituto Aggeu Magalhães - Fiocruz Pernambuco. Recife PE Brasil.
This article aims to characterize Indigenous people aged 18-23 of the Xukuru do Ororubá ethnic group, Pernambuco state, Brazil, regarding the use of dental services, self-perceived oral health, oral hygiene practices and caries experience, and socioeconomic and demographic aspects. This population-based cross-sectional study is nested in a cohort study that started in 2010 and was conducted in the Indigenous territory in 2018. Oral examinations and questionnaires were conducted with 131 Indigenous people.
View Article and Find Full Text PDFBMJ Open
January 2025
Population & Reproductive Health Section, Department of Community Health Sciences, Aga Khan University, Karachi, Pakistan
Introduction: Iron deficiency anaemia (IDA) and dental caries are prevalent diseases among Pakistani children. Limited research has been done to explore their association with permanent teeth. Given the caries susceptibility of permanent first molars and their role in the development of ideal occlusion, this study aimed to estimate caries frequency in these molars and assess its association with IDA in 7-12 year-old children.
View Article and Find Full Text PDFMaterials (Basel)
December 2024
Institute of Tissue Regeneration Engineering (ITREN), Dankook University, 119 Dandae-ro, Cheonan 31116, Republic of Korea.
A novel water-soluble root canal filling material based on sodium iodide (NaI) has been developed to overcome the limitations of existing iodine-based formulations. However, the biological stability of this approach in animal studies remains unverified. This study evaluated the biocompatibility of NaI compared to commercial root canal filling materials (Calcipex II and Vitapex) in pulpectomized canine teeth to assess its clinical applicability.
View Article and Find Full Text PDFMedicina (Kaunas)
December 2024
Department of Biochemistry, School of Dental Medicine, University of Belgrade, 11000 Belgrade, Serbia.
: Caries development is associated with poor oral hygiene, inadequate dietary habits, quantitative and qualitative food content, and a high level of bacterial plaque. Physical and chemical changes in saliva composition and particularly changes in its buffering capability play a significant role in caries development. This study aimed to determine the predictors of poor oral health among a sample of second-year dental students.
View Article and Find Full Text PDFMedicina (Kaunas)
December 2024
Department of Endodontics, Faculty of Dentistry, Ankara University, Ankara 06560, Turkey.
: The access cavity design and instrumentation system could affect the remaining root canal obturation materials in root canal retreatment. This study aimed to evaluate the efficiency of two different multi-file systems in removing obturation materials with two different access cavities utilizing micro-CT scanning. : Conservative access cavity (CAC) preparation was performed for 80 mandibular premolars.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!