scholarly journals A nanometer difference in myofilament lattice spacing of two cockroach leg muscles explains their different functions

2019 ◽  
Author(s):  
Travis Carver Tune ◽  
Weikang Ma ◽  
Thomas C. Irving ◽  
Simon Sponberg
Keyword(s):  
Lattice Spacing ◽  
Force Production ◽  
X Ray Diffraction ◽  
State Behavior ◽  
Time Resolved ◽  
Packing Structure ◽  
Leg Muscles ◽  
Force Velocity ◽  
The Difference ◽  
Tension Curves

AbstractMuscle is highly organized across scales. Consequently, small changes in arrangement of myofilaments can influence macroscopic function. Two leg muscles of a cockroach, have identical innervation, mass, twitch responses, length-tension curves, and force-velocity relationships. However, during running, one muscle is dissipative, while the other produces significant positive mechanical work. Using time resolved x-ray diffraction in intact, contracting muscle, we simultaneously measured the myofilament lattice spacing, packing structure, and macroscopic force production of these muscle to test if nanoscale differences could account for this conundrum. While the packing patterns are the same, one muscle has 1 nm smaller lattice spacing at rest. Under isometric activation, the difference in lattice spacing disappeared explaining the two muscles’ identical steady state behavior. During periodic contractions, one muscle undergoes a 1 nm greater change in lattice spacing, which correlates with force. This is the first identified feature that can account for the muscles’ different functions.

Force–Velocity–Power Profile in High-Elite Boulder, Lead, and Speed Climber Competitors

2020 ◽  
Vol 15 (7) ◽  
pp. 1012-1018
Author(s):  
Guillaume Levernier ◽  
Pierre Samozino ◽  
Guillaume Laffaye
Keyword(s):  
External Force ◽  
Coefficient Of Variation ◽  
High Speed ◽  
Intraclass Correlation ◽  
Force Production ◽  
Maximal Velocity ◽  
Mean Power ◽  
Power Profile ◽  
Force Velocity ◽  
The Difference

Purpose: To compare the force-production capacities among boulderers, lead climbers, and speed climbers during a pull-up test using a force–velocity–power profile. Methods: In total, 24 high-elite climbers (11 boulderers, 8 lead climbers, and 5 speed climbers) did 2 pull-ups at different percentages of their body mass (0%, 30%, 45%, 60%, and 70%). Force–velocity–power profile analyses were performed with the use of an accelerometer for each load. The intraclass correlation and coefficients of variation were calculated. A 1-way analysis of variance was performed with a Tukey post hoc test to assess the difference between the groups. Results: Regarding force, the coefficient of variation ranged from 1.00% to 6.18% and the intraclass correlation ranged from .98 to .99. For velocity, the coefficient of variation ranged from 2.75% to 6.62% and the intraclass correlation ranged from .84 to .95. The linear regression slope showed R2 to be between .93 and .99, confirming the high quality of the linear relationship between velocity and the external force produced during a pull-up. Boulderers presented significantly higher (P < .05) maximal power (+22.30% and +26.29%), mean power for the pull-up at body weight (+23.49% and +25.35%), and theoretical maximal velocity at zero force (+23.92% and +21.53%) than lead and speed climbers and a more significant curve increase (+35.21% compared with lead climbers). Conclusions: The reliability of the method was shown to be high. Moreover, boulderers were able to develop an important external force and had the capacity to maintain high speed when force production increased.

scholarly journals X-ray diffraction evidence for myosin-troponin connections and tropomyosin movement during stretch activation of insect flight muscle

2010 ◽  
Vol 108 (1) ◽  
pp. 120-125 ◽  
Author(s):  
Robert J. Perz-Edwards ◽  
Thomas C. Irving ◽  
Bruce A. J. Baumann ◽  
David Gore ◽  
Daniel C. Hutchinson ◽  
...  
Keyword(s):  
Cardiac Muscle ◽  
Insect Flight ◽  
Force Production ◽  
Thick Filament ◽  
Actin Binding ◽  
Stretch Activation ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray

Stretch activation is important in the mechanical properties of vertebrate cardiac muscle and essential to the flight muscles of most insects. Despite decades of investigation, the underlying molecular mechanism of stretch activation is unknown. We investigated the role of recently observed connections between myosin and troponin, called “troponin bridges,” by analyzing real-time X-ray diffraction “movies” from sinusoidally stretch-activated Lethocerus muscles. Observed changes in X-ray reflections arising from myosin heads, actin filaments, troponin, and tropomyosin were consistent with the hypothesis that troponin bridges are the key agent of mechanical signal transduction. The time-resolved sequence of molecular changes suggests a mechanism for stretch activation, in which troponin bridges mechanically tug tropomyosin aside to relieve tropomyosin’s steric blocking of myosin–actin binding. This enables subsequent force production, with cross-bridge targeting further enhanced by stretch-induced lattice compression and thick-filament twisting. Similar linkages may operate in other muscle systems, such as mammalian cardiac muscle, where stretch activation is thought to aid in cardiac ejection.

Antiphase Boundaries in Ordered Ni3FE Crystals

1969 ◽  
Vol 27 ◽  
pp. 62-63
Author(s):  
Y. H. Liu
Keyword(s):  
Domain Size ◽  
Antiphase Domain ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hardening Mechanism ◽  
Superlattice Structure ◽  
Disordered Phase ◽  
Domain Boundaries ◽  
Atomic Scattering ◽  
The Difference

Ordered Ni3Fe crystals possess a LI2 type superlattice similar to the Cu3Au structure. The difference in slip behavior of the superlattice as compared with that of a disordered phase has been well established. Cottrell first postulated that the increase in resistance for slip in the superlattice structure is attributed to the presence of antiphase domain boundaries. Following Cottrell's domain hardening mechanism, numerous workers have proposed other refined models also involving the presence of domain boundaries. Using the anomalous X-ray diffraction technique, Davies and Stoloff have shown that the hardness of the Ni3Fe superlattice varies with the domain size. So far, no direct observation of antiphase domain boundaries in Ni3Fe has been reported. Because the atomic scattering factors of the elements in NijFe are so close, the superlattice reflections are not easily detected. Furthermore, the domain configurations in NioFe are thought to be independent of the crystallographic orientations.

Visualization and Manipulation of Molecular Motion in Solid State through Photo-Induced Clusteroluminescence

2019 ◽  
Author(s):  
Haoke Zhang ◽  
Lili Du ◽  
Lin Wang ◽  
Junkai Liu ◽  
Qing Wan ◽  
...  
Keyword(s):  
Quantum Mechanics ◽  
Excited State ◽  
Solid State ◽  
Light Source ◽  
Molecular Motion ◽  
Molecular Machine ◽  
Conjugated Molecules ◽  
Time Resolved ◽  
Packing Structure ◽  
New Strategy

<p>Building molecular machine has long been a dream of scientists as it is expected to revolutionize many aspects of technology and medicine. Implementing the solid-state molecular motion is the prerequisite for a practical molecular machine. However, few works on solid-state molecular motion have been reported and it is almost impossible to “see” the motion even if it happens. Here the light-driven molecular motion in solid state is discovered in two non-conjugated molecules <i>s</i>-DPE and <i>s</i>-DPE-TM, resulting in the formation of excited-state though-space complex (ESTSC). Meanwhile, the newly formed ESTSC generates an abnormal visible emission which is termed as clusteroluminescence. Notably, the original packing structure can recover from ESTSC when the light source is removed. These processes have been confirmed by time-resolved spectroscopy and quantum mechanics calculation. This work provides a new strategy to manipulate and “see” solid-state molecular motion and gains new insights into the mechanistic picture of clusteroluminescence.<br></p>

scholarly journals Direct observations of shock-induced melting in a porous solid using time-resolved x-ray diffraction

2020 ◽  
Vol 4 (6) ◽  
Author(s):  
A. Mandal ◽  
B. J. Jensen ◽  
M. C. Hudspeth ◽  
S. Root ◽  
R. S. Crum ◽  
...  
Keyword(s):  
Porous Solid ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Direct Observations

scholarly journals A diffusion anisotropy descriptor links morphology effects of H-ZSM-5 zeolites to their catalytic cracking performance

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Xiaoliang Liu ◽  
Jing Shi ◽  
Guang Yang ◽  
Jian Zhou ◽  
Chuanming Wang ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Catalytic Cracking ◽  
Catalytic Performance ◽  
Zeolite Catalysts ◽  
Time Resolved ◽  
Cracking Performance ◽  
Morphology Effect ◽  
Ft Ir ◽  
The Difference ◽  
Dynamics Simulations

AbstractZeolite morphology is crucial in determining their catalytic activity, selectivity and stability, but quantitative descriptors of such a morphology effect are challenging to define. Here we introduce a descriptor that accounts for the morphology effect in the catalytic performances of H-ZSM-5 zeolite for C4 olefin catalytic cracking. A series of H-ZSM-5 zeolites with similar sheet-like morphology but different c-axis lengths were synthesized. We found that the catalytic activity and stability is improved in samples with longer c-axis. Combining time-resolved in-situ FT-IR spectroscopy with molecular dynamics simulations, we show that the difference in catalytic performance can be attributed to the anisotropy of the intracrystalline diffusive propensity of the olefins in different channels. Our descriptor offers mechanistic insight for the design of highly effective zeolite catalysts for olefin cracking.

scholarly journals Bulk modulus of H2O across the ice VII–ice X transition measured by time-resolved x-ray diffraction in dynamic diamond anvil cell experiments

2021 ◽  
Vol 103 (6) ◽  
Author(s):  
A. S. J. Méndez ◽  
F. Trybel ◽  
R. J. Husband ◽  
G. Steinle-Neumann ◽  
H.-P. Liermann ◽  
...  
Keyword(s):  
Bulk Modulus ◽  
Diamond Anvil Cell ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Diamond Anvil

Local atomic structure in tetragonal pure ZrO2nanopowders

2010 ◽  
Vol 43 (2) ◽  
pp. 227-236 ◽  
Author(s):  
Leandro M. Acuña ◽  
Diego G. Lamas ◽  
Rodolfo O. Fuentes ◽  
Ismael O. Fábregas ◽  
Márcia C. A. Fantini ◽  
...  
Keyword(s):  
Tetragonal Phase ◽  
Local Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Atomic Structures ◽  
Crystallite Sizes ◽  
Exafs Study ◽  
The Difference ◽  
X Ray Absorption ◽  
Good Agreement

The local atomic structures around the Zr atom of pure (undoped) ZrO2nanopowders with different average crystallite sizes, ranging from 7 to 40 nm, have been investigated. The nanopowders were synthesized by different wet-chemical routes, but all exhibit the high-temperature tetragonal phase stabilized at room temperature, as established by synchrotron radiation X-ray diffraction. The extended X-ray absorption fine structure (EXAFS) technique was applied to analyze the local structure around the Zr atoms. Several authors have studied this system using the EXAFS technique without obtaining a good agreement between crystallographic and EXAFS data. In this work, it is shown that the local structure of ZrO2nanopowders can be described by a model consisting of two oxygen subshells (4 + 4 atoms) with different Zr—O distances, in agreement with those independently determined by X-ray diffraction. However, the EXAFS study shows that the second oxygen subshell exhibits a Debye–Waller (DW) parameter much higher than that of the first oxygen subshell, a result that cannot be explained by the crystallographic model accepted for the tetragonal phase of zirconia-based materials. However, as proposed by other authors, the difference in the DW parameters between the two oxygen subshells around the Zr atoms can be explained by the existence of oxygen displacements perpendicular to thezdirection; these mainly affect the second oxygen subshell because of the directional character of the EXAFS DW parameter, in contradiction to the crystallographic value. It is also established that this model is similar to another model having three oxygen subshells, with a 4 + 2 + 2 distribution of atoms, with only one DW parameter for all oxygen subshells. Both models are in good agreement with the crystal structure determined by X-ray diffraction experiments.

Problems Associated with Kα Doublet in Residual Stress Measurements

1979 ◽  
Vol 23 ◽  
pp. 333-339
Author(s):  
S. K. Gupta ◽  
B. D. Cullity
Keyword(s):  
Residual Stress ◽  
Silicon Powder ◽  
Lattice Parameter ◽  
Diffraction Peak ◽  
Parameter Determination ◽  
X Ray Diffraction ◽  
X Ray ◽  
Analysis Techniques ◽  
The Difference ◽  
Similar Accuracy

Since the measurement of residual stress by X-ray diffraction techniques is dependent on the difference in angle of a diffraction peak maximum when the sample is examined consecutively with its surface at two different angles to the diffracting planes, it is important that these diffraction angles be obtained precisely, preferably with an accuracy of ± 0.01 deg. 2θ. Similar accuracy is desired in precise lattice parameter determination. In such measurements, it is imperative that the diffractometer be well-aligned. It is in the context of diffractometer alignment with the aid of a silicon powder standard free of residual stress that the diffraction peak analysis techniques described here have been developed, preparatory to residual stress determinations.

Time-resolved isothermal crystallization of absorbable PGA-co-PLA copolymer by synchrotron small-angle X-ray scattering and wide-angle X-ray diffraction

Polymer ◽  
2001 ◽  
Vol 42 (21) ◽  
pp. 8965-8973 ◽  
Author(s):  
Zhi-Gang Wang ◽  
Xuehui Wang ◽  
Benjamin S. Hsiao ◽  
Saša Andjelić ◽  
Dennis Jamiolkowski ◽  
...  
Keyword(s):  
Small Angle ◽  
Isothermal Crystallization ◽  
Wide Angle ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering
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