Comparison between the Flexibility of Three Different Types of Rotary NiTi Endodontic Instruments

2010 ◽  
Vol 643 ◽  
pp. 61-68 ◽  
Author(s):  
Ana Cecília Diniz Viana ◽  
Maria Guiomar de Azevedo Bahia ◽  
Vicente Tadeu Lopes Buono
Keyword(s):  
Computer Software ◽  
Chemical Properties ◽  
Bending Moment ◽  
Longitudinal Axis ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Scanning Calorimetry ◽  
Cross Sectional ◽  
Metallurgical Properties ◽  
Physical And Chemical

The aim of this study was to characterize metallurgical properties and the dimensions of three types of rotary NiTi endodontic instruments and to establish a correlation between these characteristics and the flexibility of the instruments. Their chemical composition and constitution were characterized by energy dispersive spectroscopy (EDX) and X-ray diffraction (XRD). Transformation temperatures were assessed by means of differential scanning calorimetry (DSC). Computer software was used to analyse images of the longitudinal and transverse sections for determining instrument diameter and cross-sectional area at 3mm from the tip. The flexibility of the instruments was evaluated in bending tests performed according to the ISO 3630-1 specification, in which the instruments are clamped at 3mm from their tip and bent by 45° along their longitudinal axis. The values of bending moment at 45° were correlated with instrument diameter and cross-sectional area at 3mm from the tip. The results of EDX, XRD and DSC showed that physical and chemical properties of the materials differed slightly among the files analyzed. A direct relationship was found between bending moment and the geometric characteristics of the instruments. Resistance to bending of NiTi root canal instruments depended on their geometrical shapes and metallurgical properties, but the cross-sectional configuration can be seen as an important parameter affecting this property.

scholarly journals Degradation of Plasticized Poly(1-chloroethylene) Waterproofing Membranes used as a Building Material

2021 ◽  
Vol 68 (2) ◽  
pp. 494-504
Author(s):  
Gregor Kravanja ◽  
Andrej Ivanič ◽  
Samo Lubej
Keyword(s):  
Morphological Changes ◽  
Chemical Properties ◽  
Attenuated Total Reflection ◽  
Scanning Calorimetry ◽  
Cross Sectional ◽  
Roof Area ◽  
Breaking Points ◽  
Flat Roof ◽  
Physical And Chemical ◽  
And Chemical Properties

In the present work, both unused plasticized poly(1-chloroethylene) membranes and membranes taken from a flat roof area were comprehensively analysed. First, tensile strength and elongation at breaking points were determined, followed by measurements of wettability. Secondly, morphological changes were analysed using scanning electron microscopy (SEM). To study chemical changes in aged membranes, Fourier transform infrared spectroscopy (FTIR) analysis in the attenuated total reflection mode (ATR) was used. Finally, thermogravimetric analysis and differential scanning calorimetry (TGA-DSC) were performed simultaneously to study thermal degradation. The results show obvious changes in the mechanical, physical and chemical properties of membranes caused by plasticizer loss. Surface microstructure becomes stiffer, which leads to contractions and the prevalence of voids. In cross-sectional area, average thickness values decrease. Due to the degradation of the plasticized waterproofing membranes, the roofing area had to be completely replaced.

scholarly journals Erect Position as the Alternative Technique in Achilles Tendon US: Comparison with Prone Position

2018 ◽  
Vol 6 (1) ◽  
Author(s):  
Lailatul Muqmiroh ◽  
Safinah Fajarini Yusfadhiyah ◽  
Paulus Rahardjo
Keyword(s):  
Achilles Tendon ◽  
Prone Position ◽  
Longitudinal Axis ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Erect Position ◽  
Tendon Thickness ◽  
Alternative Position ◽  
The Mean

Background : Ultrasonography (US) is the cheaper and non invasive modality to determine Achilles tendon. Prone position is the standart position of Achilles tendon US. However, it is a discomfort for an uncooperative patient and a difficult technique too. The erect position is an alternative technique of Achilles tendon US. The goal of this study is to compare the erection as an alternative position with prone as a standart position.Material and Methode: The patient who had an injury or any inflamation process of Achilles tendon were excluded. The patient underwent two positions of Achilles tendon US, 900 and dorsoflexi. Longitudinal axis measured tendon thickness and a transversal axis which covered a cross-sectional area of the tendon.Result: From all the 21 patients coming, 13 patients were males (61,9%), and eight patients were females (38,1%). The mean of tendon thickness and cross-sectional area in 900 prone positions were 4,24±0,24 mm, 30,08±2,86 mm, respectively. The mean of tendon thickness and cross-sectional area in 900 erect positions were 4,27±0,23 mm, 31,36±2,19 mm, respectively. There was no anisotropy effect during longitudinal axis examination. Conclusion: We found that there were no significant differences between a prone and erect position (p<0.05). The erect postion could be an alternative position, uncooperative patient in particular, without reducing the diagnostic value. Keywords: Achilles tendon the US, erect position, prone position, tendon thickness, cross-sectional area

Effect of Intercritical Quenching on Microstructure and Mechanical Properties of Oil Casing Steel N80

2013 ◽  
Vol 395-396 ◽  
pp. 279-283
Author(s):  
Min Huang ◽  
Yu Wang ◽  
Ya Ni Zhang ◽  
Yue Wei Xie ◽  
Shuo Feng Li
Keyword(s):  
Tensile Strength ◽  
High Strength ◽  
Optical Microscope ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Scanning Calorimetry ◽  
Cross Sectional ◽  
Study Results ◽  
The Impact ◽  
The Sacrifice

In order to improve the toughness of oil casing steel N80 without the sacrifice of its original high strength, an intercritical quenching treatment was conducted under the temperature determined by a differential scanning calorimetry (DSC) analysis. Effects of intercritical quenching on the microstructure of oil casing steel N80 were characterized by means of optical microscope (OM) and scanning electron microscope (SEM). Tensile strength, reduction of cross-sectional area and microhardness were measured to evaluate the mechanical property of oil casing steel N80 after intercritical quenching treatment. The study results show that the tensile strength and microhardness of intercritical quenched oil casing steel N80 consisting of ferrite (F) and martensite (M) is slightly lower than that of tempered oil casing steel N80 composing of sorbite (S), yet which is still higher than that of full annealled oil casing steel N80 composing of pearlite (P) and a little amount of ferrite (F). In particular, the reduction of cross-sectional area of oil casing steel N80 intercritical quenched at 740°C is higher than those of tempered and full annealled. Additionally, both dimple and cleavage can be found on the impact fracture surface of N80 steel after intercritical quenching at 740°C. The toughness of oil casing steel N80 can be obviously improved by the intercritical quenching treatment at 740°C due to the formation of ferrite (F).

Anatomy and biomechanics of quadratus lumborum

2008 ◽  
Vol 222 (2) ◽  
pp. 151-159 ◽  
Author(s):  
S Phillips ◽  
S Mercer ◽  
N Bogduk
Keyword(s):  
Lumbar Spine ◽  
Quantitative Data ◽  
Bending Moment ◽  
Cross Sectional Area ◽  
Erector Spinae ◽  
Sectional Area ◽  
Lateral Bending ◽  
Cross Sectional ◽  
Quadratus Lumborum ◽  
Attachment Orientation

Various actions on the lumbar spine have been attributed to quadratus lumborum, but they have not been substantiated by quantitative data. The present study was undertaken to determine the magnitude of forces and moments that quadratus lumborum could exert on the lumbar spine. The fascicular anatomy of quadratus lumborum was studied in six embalmed cadavers. For each fascicle, the sites of attachment, orientation, and physiological cross-sectional area were determined. The fascicular anatomy varied considerably, between sides and between specimens, with respect to the number of fascicles, their prevalence, and their sizes. Approximately half of the fascicles act on the twelfth rib, and the rest act on the lumbar spine. The more consistently present fascicles were incorporated, as force-equivalents, into a model of quadratus lumborum in order to determine its possible actions. The magnitudes of the compression forces exerted by quadratus lumborum on the lumbar spine, the extensor moment, and the lateral bending moment, were each no greater than 10 per cent of those exerted by erector spinae and multifidus. These data indicate that quadratus lumborum has no more than a modest action on the lumbar spine, in quantitative terms. Its actual role in spinal biomechanics has still to be determined.

Pelvic Canal Narrowing Caused by Triple Pelvic Osteotomy in the Dog

1994 ◽  
Vol 07 (03) ◽  
pp. 110-113 ◽  
Author(s):  
D. L. Holmberg ◽  
M. B. Hurtig ◽  
H. R. Sukhiani
Keyword(s):  
Postoperative Complications ◽  
Pelvic Osteotomy ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Canal Width ◽  
Operative Complications ◽  
Post Operative Complications

SummaryDuring a triple pelvic osteotomy, rotation of the free acetabular segment causes the pubic remnant on the acetabulum to rotate into the pelvic canal. The resulting narrowing may cause complications by impingement on the organs within the pelvic canal. Triple pelvic osteotomies were performed on ten cadaver pelves with pubic remnants equal to 0, 25, and 50% of the hemi-pubic length and angles of acetabular rotation of 20, 30, and 40 degrees. All combinations of pubic remnant lengths and angles of acetabular rotation caused a significant reduction in pelvic canal-width and cross-sectional area, when compared to the inact pelvis. Zero, 25, and 50% pubic remnants result in 15, 35, and 50% reductions in pelvic canal width respectively. Overrotation of the acetabulum should be avoided and the pubic remnant on the acetabular segment should be minimized to reduce postoperative complications due to pelvic canal narrowing.When performing triple pelvic osteotomies, the length of the pubic remnant on the acetabular segment and the angle of acetabular rotation both significantly narrow the pelvic canal. To reduce post-operative complications, due to narrowing of the pelvic canal, overrotation of the acetabulum should be avoided and the length of the pubic remnant should be minimized.

DETERMINATION OF THE FUNCTION OF THE ROD’S CROSS-SECTIONAL AREA USING VIBRATION EIGENFREQUENCIES

2020 ◽  
Vol 0 (4) ◽  
pp. 19-24
Author(s):  
I.M. UTYASHEV ◽  
◽  
A.A. AITBAEVA ◽  
A.A. YULMUKHAMETOV ◽  
◽  
...  
Keyword(s):  
Cross Sectional Area ◽  
Variable Cross ◽  
Sectional Area ◽  
Longitudinal Vibrations ◽  
Cross Sectional ◽  
Method Error ◽  
Various Boundary Conditions ◽  
Elastic Fixation ◽  
Crosssectional Area

The paper presents solutions to the direct and inverse problems on longitudinal vibrations of a rod with a variable cross-sectional area. The law of variation of the cross-sectional area is modeled as an exponential function of a polynomial of degree n . The method for reconstructing this function is based on representing the fundamental system of solutions of the direct problem in the form of a Maclaurin series in the variables x and λ. Examples of solutions for various section functions and various boundary conditions are given. It is shown that to recover n unknown coefficients of a polynomial, n eigenvalues are required, and the solution is dual. An unambiguous solution was obtained only for the case of elastic fixation at one of the rod’s ends. The numerical estimation of the method error was made using input data noise. It is shown that the error in finding the variable crosssectional area is less than 1% with the error in the eigenvalues of longitudinal vibrations not exceeding 0.0001.

Changes in the parameters of nasal breathing and parameters of the upper respiratory tract during orthognathic operations in patients with II and III skeletal class of jaw anomalies

2020 ◽  
pp. 22-27
Author(s):  
S.Sh. Gammadaeva ◽  
M.I. Misirkhanova ◽  
A.Yu. Drobyshev
Keyword(s):  
Respiratory Tract ◽  
Nasal Cavity ◽  
Nasal Septum ◽  
Cross Sectional Area ◽  
Upper Respiratory Tract ◽  
Sectional Area ◽  
Nasal Breathing ◽  
Cross Sectional ◽  
Skeletal Class ◽  
Upper Respiratory

The study analyzed the functional parameters of nasal breathing, linear parameters of the nasal aperture, nasal cavity and nasopharynx, volumetric parameters of the upper airways in patients with II and III skeletal class of jaw anomalies before and after orthognathic surgery. The respiratory function of the nose was assessed using a rhinomanometric complex. According to rhinoresistometry data, nasal resistance and hydraulic diameter were assessed. According to the data of acoustic rhinometry, the minimum cross-sectional area along the internal valve, the minimum cross-sectional area on the head of the inferior turbinate and nasal septum and related parameters were estimated. According to the CBCT data, the state of the nasal septum, the inferior turbinates, the nasal aperture, the state of the nasal cavity, and the linear values of the upper respiratory tract (nasopharynx) were analyzed. The patients were divided into 4 groups according to the classification of the patency of the nasal passages by

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