Ni-Ti ROTARY INSTRUMENT FRACTURE ANALYSIS AFTER CLINICAL USE. STRUCTURE CHANGES IN USED INSTRUMENTS

During clinical operation in root canals, NiTi endodontic rotary instruments are subjected to alternating tension and compression and are prone to accidental fracture without prior warning. Once broken, extracting the fractured part from the canal is difficult and is annoying to both the patient and the dentist. Warning of an imminent fracture during clinical use will be a great help to avoid medical and legal complications. To this end, a monitoring technique that involves the picking up and analysis of the stress wave signals due to the cutting and rubbing at the canal wall-instrument blade interface was investigated. Both the stress wave conducted through solid and the sound wave conducted in air were monitored. The former was picked up by a Fiber Bragg Grating (FBG) and the latter with a microphone. When cracking developed in a rotary instrument, we expect the natural vibration frequency of the instrument as well as the characteristics of cutting/rubbing with the canal wall change. From the raw signal intensity history, it is possible to differentiate whether the instrument is operating but there is no clue when a fatigue crack has initiated. By employing Fast Fourier Transform (FFT) on the signal, we can reveal the energy associated with different frequencies. With characteristic frequency we refer to the frequency that is associated with the highest signal intensity. It was found that the energy intensity of the characteristic frequency varied in a well-defined pattern during the process of fatigue testing of the rotary instrument. Towards the end of fatigue life, a large intensity spike of the characteristic frequency was observed and this was shown to be associated with the occurrence of a fatigue crack. It is hoped that with this information, the fatigue failure of rotary instruments can be closely monitored to avoid/alleviate the occurrence of unexpected fracture during clinical use.

Download Full-text

Determination of interface width using EELS fine structure changes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100087963 ◽

1991 ◽

Vol 49 ◽

pp. 730-731

Author(s):

Vinayak P. Dravid ◽

M.R. Notis ◽

C.E. Lyman

Keyword(s):

Fine Structure ◽

Materials Science ◽

Input Parameter ◽

Core Loss ◽

Directionally Solidified ◽

Interface Width ◽

Structure Changes ◽

Important Input ◽

Directionally Solidified Eutectics

The concept of interfacial width is often invoked in many materials science phenomena which relate to the structure and properties of internal interfaces. The numerical value of interface width is an important input parameter in diffusion equations, sintering theories as well as in many electronic devices/processes. Most often, however, this value is guessed rather than determined or even estimated. In this paper we present a method of determining the effective structural and electronic- structural width of interphase interfaces using low- and core loss fine structure effects in EELS spectra.The specimens used in the study were directionally solidified eutectics (DSEs) in the system; NiO-ZrO2(CaO), NiO-Y2O3 and MnO-ZrO2(ss). EELS experiments were carried out using a VG HB-501 FE STEM and a Hitachi HF-2000 FE TEM.

Download Full-text

In-Situ Observation of Clay Minerals Hydrated and Intercalated With Liquid Chemicals Using Film-Sealed Environmental Cell

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s1431927600000908 ◽

1980 ◽

Vol 38 ◽

pp. 208-209 ◽

Cited By ~ 1

Author(s):

K. Fukushima ◽

N. Kohyama ◽

A. Fukami

Keyword(s):

Carbon Film ◽

Resolving Power ◽

In Situ Observation ◽

Interlayer Water ◽

Saturated Water ◽

Structure Changes ◽

Environmental Cell ◽

Gas Layer ◽

20 Nm

A film-sealed high resolution environmental cell(E.C) for observing hydrated materials had been developed by us(l). Main specification of the E.C. is as follows: 1) Accelerated voltage; 100 kV. 2) Gas in the E.C.; saturated water vapour with carrier gas of 50 Torr. 3) Thickness of gas layer; 50 μm. 4) Sealing film; evaporated carbon film(20 nm thick) with plastic microgrid. 5) Resolving power; 1 nm. 6) Transmittance of electron beam; 60% at 100 kV. The E.C. had been successfully applied to the study of hydrated halloysite(2) (3). Kaolin minerals have no interlayer water and are basically non-expandable but form intercalation compounds with some specific chemicals such as hydrazine, formamide and etc. Because of these compounds being mostly changed in vacuum, we tried to reveal the structure changes between in wet air and in vacuum of kaolin minerals intercalated with hydrazine and of hydrated state of montmori1lonite using the E.C. developed by us.

Download Full-text

Assessing Functional Language in School-Aged Children Using Language Sample Analysis

Perspectives of the ASHA Special Interest Groups ◽

10.1044/2020_persp-19-00079 ◽

2020 ◽

Vol 5 (3) ◽

pp. 622-636

Author(s):

John Heilmann ◽

Alexander Tucci ◽

Elena Plante ◽

Jon F. Miller

Keyword(s):

Computer Hardware ◽

School Age Children ◽

Functional Language ◽

School Age ◽

Clinical Use ◽

Sample Analysis ◽

Validity And Reliability ◽

Language Sample Analysis ◽

Accuracy And Repeatability ◽

Language Sample

Purpose The goal of this clinical focus article is to illustrate how speech-language pathologists can document the functional language of school-age children using language sample analysis (LSA). Advances in computer hardware and software are detailed making LSA more accessible for clinical use. Method This clinical focus article illustrates how documenting school-age student's communicative functioning is central to comprehensive assessment and how using LSA can meet multiple needs within this assessment. LSA can document students' meaningful participation in their daily life through assessment of their language used during everyday tasks. The many advances in computerized LSA are detailed with a primary focus on the Systematic Analysis of Language Transcripts (Miller & Iglesias, 2019). The LSA process is reviewed detailing the steps necessary for computers to calculate word, morpheme, utterance, and discourse features of functional language. Conclusion These advances in computer technology and software development have made LSA clinically feasible through standardized elicitation and transcription methods that improve accuracy and repeatability. In addition to improved accuracy, validity, and reliability of LSA, databases of typical speakers to document status and automated report writing more than justify the time required. Software now provides many innovations that make LSA simpler and more accessible for clinical use. Supplemental Material https://doi.org/10.23641/asha.12456719

Download Full-text

Translation Research for the Rehabilitation of Left Spatial Neglect and Associated Disorders of Attention in Stroke Patients

Perspectives on Neurophysiology and Neurogenic Speech and Language Disorders ◽

10.1044/nnsld18.2.55 ◽

2008 ◽

Vol 18 (2) ◽

pp. 55-65 ◽

Cited By ~ 2

Author(s):

Nkiruka Arene ◽

Argye E. Hillis

Keyword(s):

Theoretical Basis ◽

Attention Bias ◽

Spatial Neglect ◽

Clinical Use ◽

Stroke Patients ◽

Translation Research ◽

Unilateral Neglect ◽

Assessment And Treatment ◽

Sound Theoretical Basis ◽

Review Current

Abstract The syndrome of unilateral neglect, typified by a lateralized attention bias and neglect of contralateral space, is an important cause of morbidity and disability after a stroke. In this review, we discuss the challenges that face researchers attempting to elucidate the mechanisms and effectiveness of rehabilitation treatments. The neglect syndrome is a heterogeneous disorder, and it is not clear which of its symptoms cause ongoing disability. We review current methods of neglect assessment and propose logical approaches to selecting treatments, while acknowledging that further study is still needed before some of these approaches can be translated into routine clinical use. We conclude with systems-level suggestions for hypothesis development that would hopefully form a sound theoretical basis for future approaches to the assessment and treatment of neglect.

Download Full-text