How Bone Tissue and Cells Experience Elevated Temperatures During Orthopaedic Cutting: An Experimental and Computational Investigation

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Eimear B. Dolan ◽  
Ted J. Vaughan ◽  
Glen L. Niebur ◽  
Conor Casey ◽  
David Tallon ◽  
...  
Keyword(s):  
Bone Tissue ◽  
Orthopaedic Surgery ◽  
Computational Models ◽  
Thermal Damage ◽  
Elevated Temperatures ◽  
A Priori ◽  
Computational Investigation ◽  
Bone Injury ◽  
Analytical Expressions ◽  
Insight Into

During orthopaedic surgery elevated temperatures due to cutting can result in bone injury, contributing to implant failure or delayed healing. However, how resulting temperatures are experienced throughout bone tissue and cells is unknown. This study uses a combination of experiments (forward-looking infrared (FLIR)) and multiscale computational models to predict thermal elevations in bone tissue and cells. Using multiple regression analysis, analytical expressions are derived allowing a priori prediction of temperature distribution throughout bone with respect to blade geometry, feed-rate, distance from surface, and cooling time. This study offers an insight into bone thermal behavior, informing innovative cutting techniques that reduce cellular thermal damage.

Understanding the Effects of Thermal Elevations Associated With Orthopedic Intervention: An Experimental and Computational Investigation

2013 ◽  
Author(s):  
E. B. Dolan ◽  
T. J. Vaughan ◽  
G. L. Niebur ◽  
D. Tallon ◽  
L. M. McNamara
Keyword(s):  
Bone Tissue ◽  
Computational Models ◽  
Thermal Damage ◽  
Elevated Temperatures ◽  
Bone Cells ◽  
The Body ◽  
Surrounding Soft Tissue ◽  
Multi Scale ◽  
Orthopedic Surgeons

Specialized surgical cutting instruments are required to provide orthopedic surgeons with access to joints of the body, without causing extensive harm to native tissue, thus enhancing post-operative outcome. Orthopaedic intervention inevitably exposes bone tissue to elevated temperatures due to mechanical abrasion. Elevated temperatures lead to thermal necrosis and apoptosis of bone cells, surrounding soft tissue, bone marrow and stem cells crucial for postoperative healing (1–4). Thermally damaged bone tissue is subsequently resorbed and in severe cases replaced by connective tissue (2, 5) Bone thermal damage occurs when the local temperature exceeds a thermal threshold, largely recognised as ≥47°C (4, 6). Furthermore, it has been proposed that the area of bone to experience thermal damage is directly proportional to the duration of exposure to the heat source (7, 8). However, precise thermal elevations occurring throughout bone during surgical cutting are not well defined. It is also unclear whether temperatures generated in osteocytes in vivo are sufficient to induce cellular responses. Experimental analysis of temperature generation throughout bone is challenging due to its complex heterogeneous composition. There is a specific need for advanced 3D computational models that incorporate multi-scale variability in both bone tissue composition and thermal properties to predict how organ level thermal elevations are distributed throughout bone cells and tissue during orthopaedic cutting procedures.

Experimental Validation of an Inverse Heat Transfer Algorithm for Optimizing Hyperthermia Treatments

2006 ◽  
Vol 128 (4) ◽  
pp. 505-515 ◽  
Author(s):  
F. Scott Gayzik ◽  
Elaine P. Scott ◽  
Tahar Loulou
Keyword(s):  
Computational Models ◽  
Thermal Damage ◽  
Elevated Temperatures ◽  
Treatment Protocol ◽  
Bioheat Transfer ◽  
Transient Temperature ◽  
Transfer Model ◽  
Minimization Algorithm ◽  
Hyperthermia Treatment ◽  
Extent Of Damage

Hyperthermia is a cancer treatment modality in which body tissue is exposed to elevated temperatures to destroy cancerous cells. Hyperthermia treatment planning refers to the use of computational models to optimize the heating protocol with the goal of isolating thermal damage to predetermined treatment areas. This paper presents an algorithm to optimize a hyperthermia treatment protocol using the conjugate gradient method with the adjoint problem. The output of the minimization algorithm is a heating protocol that will cause a desired amount of thermal damage. The transient temperature distribution in a cylindrical region is simulated using the bioheat transfer equation. Temperature and time are integrated to calculate the extent of thermal damage in the region via a first-order rate process based on the Arrhenius equation. Several validation experiments are carried out by applying the results of the minimization algorithm to an albumen tissue phantom. Comparisons of metrics describing the damage region (the height and radius of the volume of thermally ablated phantom) show good agreement between the desired extent of damage and the measured extent of damage. The sensitivity of the bioheat transfer model and the Arrhenius damage model to their constituent parameters is calculated to create a tolerable range of error between the desired and measured extent of damage. The measured height and radius of the ablated region fit well within the tolerable range of error found in the sensitivity analysis.

Facing extremes: archaeal surface-layer (glyco)proteins

Microbiology ◽  
2003 ◽  
Vol 149 (12) ◽  
pp. 3347-3351 ◽  
Author(s):  
Jerry Eichler
Keyword(s):  
Surface Layer ◽  
Structural Integrity ◽  
Elevated Temperatures ◽  
Protein Biosynthesis ◽  
Extreme Environments ◽  
Archaeal Protein ◽  
The Face ◽  
Micro Organisms ◽  
Physical Challenges ◽  
Insight Into

Archaea are best known in their capacities as extremophiles, i.e. micro-organisms able to thrive in some of the most drastic environments on Earth. The protein-based surface layer that envelopes many archaeal strains must thus correctly assemble and maintain its structural integrity in the face of the physical challenges associated with, for instance, life in high salinity, at elevated temperatures or in acidic surroundings. Study of archaeal surface-layer (glyco)proteins has thus offered insight into the strategies employed by these proteins to survive direct contact with extreme environments, yet has also served to elucidate other aspects of archaeal protein biosynthesis, including glycosylation, lipid modification and protein export. In this mini-review, recent advances in the study of archaeal surface-layer (glyco)proteins are discussed.

Thermal Breakdown Kinetics of 1-Ethyl-3-Methylimidazolium Ethylsulfate Measured Using Quantitative Infrared Spectroscopy

2017 ◽  
Vol 71 (12) ◽  
pp. 2626-2631 ◽  
Author(s):  
Jeffrey L. Wheeler ◽  
McKinley Pugh ◽  
S. Jake Atkins ◽  
Jason M. Porter
Keyword(s):  
Thermal Stability ◽  
Room Temperature ◽  
Computational Models ◽  
Elevated Temperatures ◽  
Molar Absorptivity ◽  
Ir Absorption ◽  
Optical Cell ◽  
Multiple Samples ◽  
Kinetics Of ◽  
Thermal Stability Of

In this work, the thermal stability of the room temperature ionic liquid (RTIL) 1-ethyl-3-methylimidazolium ethylsulfate ([EMIM][EtSO4]) is investigated using infrared (IR) spectroscopy. Quantitative IR absorption spectral data are measured for heated [EMIM][EtSO4]. Spectra have been collected between 25 ℃ and 100 ℃ using a heated optical cell. Multiple samples and cell pathlengths are used to determine quantitative values for the molar absorptivity of [EMIM][EtSO4]. These results are compared to previous computational models of the ion pair. These quantitative spectra are used to measure the rate of thermal decomposition of [EMIM][EtSO4] at elevated temperatures. The spectroscopic measurements of the rate of decomposition show that thermogravimetric methods overestimate the thermal stability of [EMIM][EtSO4].

Diabetes Self-Care Behaviors and Barriers to Clinical Care During COVID-19 Pandemic for Marshallese Adults

2022 ◽  
pp. 263501062110653
Author(s):  
Rachel S. Purvis ◽  
Ramey A. Moore ◽  
Britni L. Ayers ◽  
Holly C. Felix ◽  
Sheldon Riklon ◽  
...  
Keyword(s):  
Health Care ◽  
Social Media ◽  
Health Education ◽  
Health Care Provider ◽  
Care Provider ◽  
Clinical Care ◽  
A Priori ◽  
Self Care ◽  
Qualitative Descriptive ◽  
Insight Into

Purpose: The purpose of the study was to explore experiences of Marshallese adults related to diabetes self-care behaviors during the COVID-19 pandemic. Methods: A qualitative descriptive design was utilized to understand participants’ diabetes self-care behaviors during the pandemic. Nine focus groups with 53 participants were held via videoconference and conducted in English, Marshallese, or a mixture of both languages. A priori codes based on diabetes self-care behaviors provided a framework for analyzing and summarizing participant experiences. Results: Both increases and decreases in healthy eating and exercise were described, with improvements in health behaviors attributed to health education messaging via social media. Participants reported increased stress and difficulty monitoring and managing glucose. Difficulty obtaining medication and difficulty seeing their health care provider regularly was reported and attributed to health care provider availability and lack of insurance due to job loss. Conclusions: The study provides significant insight into the reach of health education campaigns via social media and provides important information about the reasons for delays in care, which extend beyond fear of contracting COVID-19 to structural issues.

scholarly journals CONSTRAINING THE PREFERRED-FRAME α1, α2 PARAMETERS FROM SOLAR SYSTEM PLANETARY PRECESSIONS

2014 ◽  
Vol 23 (01) ◽  
pp. 1450006 ◽  
Author(s):  
L. IORIO
Keyword(s):  
Binary System ◽  
Solar System ◽  
Relative Motion ◽  
A Priori ◽  
The Other ◽  
Preferred Frame ◽  
General Relativistic ◽  
Ppn Parameters ◽  
Invariable Plane ◽  
Analytical Expressions

Analytical expressions for the orbital precessions affecting the relative motion of the components of a local binary system induced by Lorentz-violating Preferred Frame Effects (PFE) are explicitly computed in terms of the Parametrized Post-Newtonian (PPN) parameters α1, α2. Preliminary constraints on α1, α2 are inferred from the latest determinations of the observationally admitted ranges [Formula: see text] for any anomalous Solar System planetary perihelion precessions. Other bounds existing in the literature are critically reviewed, with particular emphasis on the constraint [Formula: see text] based on an interpretation of the current close alignment of the Sun's equator with the invariable plane of the Solar System in terms of the action of a α2-induced torque throughout the entire Solar System's existence. Taken individually, the supplementary precessions [Formula: see text] of Earth and Mercury, recently determined with the INPOP10a ephemerides without modeling PFE, yield α1 = (0.8±4) × 10-6 and α2 = (4±6) × 10-6, respectively. A linear combination of the supplementary perihelion precessions of all the inner planets of the Solar System, able to remove the a priori bias of unmodeled/mismodeled standard effects such as the general relativistic Lense–Thirring precessions and the classical rates due to the Sun's oblateness J2, allows to infer α1 = (-1 ± 6) × 10-6, α2 = (-0.9 ± 3.5) × 10-5. Such figures are obtained by assuming that the ranges of values for the anomalous perihelion precessions are entirely due to the unmodeled effects of α1 and α2. Our bounds should be improved in the near-mid future with the MESSENGER and, especially, BepiColombo spacecrafts. Nonetheless, it is worthwhile noticing that our constraints are close to those predicted for BepiColombo in two independent studies. In further dedicated planetary analyses, PFE may be explicitly modeled to estimate α1, α2 simultaneously with the other PPN parameters as well.

Experimental Investigation on Grinding Temperature of Titanium Alloy

2014 ◽  
Vol 1027 ◽  
pp. 127-130 ◽  
Author(s):  
Bing Jun Hao ◽  
Zhi Gang Dong ◽  
Ren Ke Kang ◽  
Huan Wang ◽  
Ke Cao
Keyword(s):  
Titanium Alloy ◽  
Structural Changes ◽  
Thermal Damage ◽  
Elevated Temperatures ◽  
Chemical Properties ◽  
Grinding Temperature ◽  
Physical And Chemical Properties ◽  
Machine Material ◽  
Physical And Chemical ◽  
And Chemical Properties

Titanium alloy has been widely used in aeronautics and astronautics industry owing to its unique combinations of properties. The unique physical and chemical properties of titanium alloy make it a typical difficult-to-machine material. The elevated temperatures at the machining zones may cause thermal damage, residual stress and micro-structural changes in the surface layer of titanium alloy during grinding. In this study, grinding experiments were performed on the titanium alloy, and the grinding temperature was experimentally tested with the grindable thermocouples. The effects of the grinding parameters on the grinding temperature were analyzed. The grinding temperature rises with the increase of grinding speed and grinding depth.

Light Directs Monomer Coordination in Catalyst-Free Grignard Photopolymerization

2021 ◽  
Author(s):  
Eliot Woods ◽  
Alexandra Berl ◽  
Leanna Kantt ◽  
Michael Wasielewski ◽  
Brandon E. Haines ◽  
...  
Keyword(s):  
Conjugated Polymers ◽  
Radical Anion ◽  
Elevated Temperatures ◽  
Spectroscopic Studies ◽  
Computational Investigation ◽  
Catalyst Free ◽  
Active Layers ◽  
End Groups ◽  
Type Coupling

π-Conjugated polymers can serve as active layers in flexible and lightweight electronics, and are conventionally synthesized by transition-metal-mediated polycondensation at elevated temperatures. We recently reported a photopolymerization of electron-deficient heteroaryl Grignard monomers that enables the catalyst-free synthesis of n-type π-conjugated polymers. Herein we provide an experimental and computational investigation of the mechanism of this photopolymerization. Spectroscopic studies performed <i>in situ</i> and after quenching reveal that the propagating species is a radical anion with halide end groups. DFT calculations for model oligomers suggest a Mg-templated S<sub>RN</sub>1-type coupling, in which Grignard monomer coordination to the radical anion chain avoids the formation of free sp<sup>2</sup> radicals and enables C–C bond formation with very low barriers. We find that light plays an unusual role in the reaction, photoexciting the radical anion chain to shift electron density to the termini and thus favor productive monomer binding.

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