Unexpected Contraction Research Articles

Modulating muscle activity using GABA inhibitors

Introduction: Overuse of muscles, stress and dehydration are some of the reasons for muscle spasms. Muscle cramps often resolve on their own but in some cases medical intervention is required. Aim: The aim of this article is to study the modulating muscle activity using GABA inhibitors. Materials and Methods: Treatment plans for bruxism include different ways for modulating muscle activity, which should be studied. Results: A spasm is an involuntary, unexpected contraction of one or more muscles.Muscle spasms can happen in any muscle of the human body. The most common reasons for the occurrence of spasms are overuse of a muscle, dehydration or stress. Discussion: Gamma-aminobutyric acid (GABA) serves as the main inhibitory neurotransmitter in the developed, mature central nervous system of mammals. GABA A receptors are ligand-activated chloride channels. GABA receptors are the main focus of this study because of their wide spread throughout the mammalian nervous system. In a recent study from 2017, Gervasi, Sisti and team from Baltimore discovered that the regular application of thiocolchicoside-based foam topically on m. rectus et biceps femoris reduced the risk of muscle cramps, muscle pain and improved the overall performance of the athletes in the study group. Conclusion: This discovery, along with the known properties of thiocolchicoside and its structure, present an interesting perspective when considering new ways to treat muscle spasms. Dermal patches ensure the gradual release of a substance in a certain area through the skin. The idea is to develop a dermal patch for application on m. masseter et temporalis when treating patients with bruxism.

Superstructured Macroporous Carbon Rods Composed of Defective Graphitic Nanosheets for Efficient Oxygen Reduction Reaction.

Rationally designed carbon materials with superstructures are promising candidates in applications such as electrocatalysis. However, the synthesis of highly porous carbon superstructures with macropores and carbon defects from a simple crystalline solid remains challenging. In this work, superstructured macroporous carbon rods composed of defective graphitic nanosheets are synthesized by direct carbonization of crystalline poly tannic acid (PTA) rods as precursors. During carbonization, PTA rods with a highly ordered lamellar structure induce a spatially confined two‐step localized contraction that takes place in different dimensions and directions in each step. The unexpected contraction behavior results in the sponge‐like macroporous carbon superstructure with large surface area, high porosity, and abundant defects, thus showing a superior electrocatalytic performance with high activity and selectivity for oxygen reduction reaction. The study provides new understandings in the design of functional carbon materials with distinctive structures and applications.

Three-dimensional reconstruction of a whole insect reveals its phloem sap-sucking mechanism at nano-resolution

Using serial block-face scanning electron microscopy, we report on the internal 3D structures of the brown planthopper, Nilaparvata lugens (Hemiptera: Delphacidae) at nanometer resolution for the first time. Within the reconstructed organs and tissues, we found many novel and fascinating internal structures in the planthopper such as naturally occurring three four-way rings connecting adjacent spiracles to facilitate efficient gas exchange, and fungal endosymbionts in a single huge insect cell occupying 22% of the abdomen volume to enable the insect to live on plant sap. To understand the muscle and stylet movement during phloem sap-sucking, the cephalic skeleton and muscles were reconstructed in feeding nymphs. The results revealed an unexpected contraction of the protractors of the stylets and suggested a novel feeding model for the phloem sap-sucking.

Immediate changes in anticipatory muscle activity after unexpected muscle contraction training

Immediate changes in anticipatory muscle activity after unexpected muscle contraction training

Hydroxyl-rich macromolecules enable the bio-inspired synthesis of single crystal nanocomposites

Acidic macromolecules are traditionally considered key to calcium carbonate biomineralisation and have long been first choice in the bio-inspired synthesis of crystalline materials. Here, we challenge this view and demonstrate that low-charge macromolecules can vastly outperform their acidic counterparts in the synthesis of nanocomposites. Using gold nanoparticles functionalised with low charge, hydroxyl-rich proteins and homopolymers as growth additives, we show that extremely high concentrations of nanoparticles can be incorporated within calcite single crystals, while maintaining the continuity of the lattice and the original rhombohedral morphologies of the crystals. The nanoparticles are perfectly dispersed within the host crystal and at high concentrations are so closely apposed that they exhibit plasmon coupling and induce an unexpected contraction of the crystal lattice. The versatility of this strategy is then demonstrated by extension to alternative host crystals. This simple and scalable occlusion approach opens the door to a novel class of single crystal nanocomposites.

Variables associated with mouth breathing diagnosis in children based on a multidisciplinary assessment.

: This study was conducted to identify variables associated with mouth breathing diagnosis in children, based on multidisciplinary domains. 119 children, six to 12 years old, underwent anamnesis, speech therapy (orofacial structures and stomatognathic functions), otorhinolaryngologic (OTRL) with clinical and endoscopic examinations, dental (occlusion) and physiotherapy (body posture and nasal patency) assessments. Nasal patency was evaluated using Peak Nasal Inspiratory Flow (PNIF) and the Nasal Obstruction Symptom Evaluation (NOSE) scale. A multiple logistic regression was performed considering breathing mode as the dependent variable and the co-variables from each multidisciplinary assessment as associated variables. Association with MB diagnosis was found in each professional domain with: nasal obstruction report (Odds ratio - OR=5.55), time of pacifier use (OR=1.25), convex facial type (OR=3.78), obtuse nasal angle (OR=4.30), half-open or open lip posture (OR=4.13), tongue position on the mouth floor (OR=5.88), reduced hard palate width (OR=2.99), unexpected contraction during mastication (OR=2.97), obstructive pharyngeal tonsils (OR=8.37), Angle Class II malocclusion (OR=10.85) and regular gingival maintenance (OR=2.89). We concluded that a multidisciplinary diagnosis is important, given that each evaluation domain, including OTRL, dental and speech therapy, presented variables associated with MB diagnosis. Body posture and nasal patency variables were not associated with MB.

Synthesis of the 10-oxabicyclo[5.2.1]decane framework present in bioactive natural products.

The present work deals with the synthesis of the 10-oxabicyclo[5.2.1]decane framework present in bioactive natural products like physalins, with potential as antitumor agents. This synthetic methodology involves several key reactions: (a) synthesis of polyfunctionalized cycloheptenones by [4 + 3] cycloaddition reactions of furan precursors with oxyallyl cations; (b) Nicholas reaction with propargyl cations stabilized as dicobalt hexacarbonyl complexes; (c) demetallation and hydration of the resulting acetylenes; (d) stereoconvergent aldol cyclization to generate a key oxatricyclic intermediate and (e) a β-fragmentation process that affords, under hypoiodite photolysis, the desired product with moderate to good yield. The final compounds are the result of a radicalary β-fragmentation at the level of C2-C6 with respect to the tertiary hydroxyl group on C6, with an unexpected contraction from a ten- to a nine-membered ring system, via a radical addition to the carbonyl group on C4. The synthetic methodology has been scaled up to multigram level with good overall yield. Further biological, biochemical and biophysical studies are being carried out in our laboratory on these 1,7-epoxycyclononane derivatives to determine the potential of this kind of oxabicyclic compound as future hits and/or leads for the development of new anticancer drugs. The preliminary evaluation of the anticancer activity of the representative synthesized compounds, against the leukaemia cancer cell lines K-562 and SR, shows a promising activity with a GI50 = 0.01 μM and a LC50 = 7.4 μM for a conveniently functionalized 10-oxabicyclo[5.2.1]decane.

Greatly Enhanced Thermal Contraction at Room Temperature by Carbon Nanotubes

A crosslinked polyarylamide polymer exhibits novel photothermal behavior, that is, reversible giant contraction in response to near infrared irradiation in addition to normal thermal expansion. Such reversibility is seldom found in a polymeric system. Due to the amphiphilic nature of the benzocyclobutene‐containing triblock copolymer precursor with polyarylamide interacting strongly with few‐walled carbon nanotubes (FWCNTs), they are dispersed extremely well in the polymer solution at a loading up to at least 5 wt%. Also, strained carbon double bonds on FWCNTs can directly form covalent linkages with the benzocyclobutene groups on the polymer chains via cyclo‐addition. The incorporation of FWCNTs increases mechanical stiffness two‐fold. Exploiting the ability of FWCNTs to effectively convert photon energy into heat and to provide conductive pathways, the NIR‐induced unexpected contraction stress can be further increased dramatically. The systematic study suggests that there is an optimal CNT concentration. At 3 wt% FWCNTs, the enhancement factor for contraction stress is almost 24: 166 kPa with 3 wt% FWCNTs versus 7 kPa without FWCNTs. The colossal photothermal contraction stress generated by this new composite film at ambient condition upon NIR stimulation can lead to the development of new NIR actuators, for example, for biological applications, and create new material platforms for green energy conversion.

Direct evidence of a multicentre halogen bond: unexpected contraction of the P–XXX–P fragment in triphenylphosphine dihalides

Triphenylhalophosphonium halides, Ph(3)PX(2), form crystals comprising bridged linear cations [Ph(3)P-X-X-X-PPh(3)](+) where the X(3) bridge is shortened from 6.56 Å in Cl-Cl-Cl to 6.37 Å in the Br-Br-Br system. It is proposed that this structure is stabilised by five-centre/six-electron (5c-6e) hypervalent interactions.

Powder X-Ray Diffraction Study of the Hydration and Leaching Behavior of Nontronite

AbstractNontronite is a significant component of commercially important nickel laterite ores. Its behavior during high-pressure acid leaching of such ores may have an impact upon the efficiency of the process. The present study was conducted in order to further investigate the response of this material during high-pressure acid leaching. In situ synchrotron powder X-ray diffraction data were collected from a number of nontronite samples during hydration and leaching reactions at ambient and elevated temperatures. The present study followed previous high-pressure acid-leaching studies of nontronite where unexpected contraction and expansion behavior of the clay was observed by means of in situ X-ray diffraction. In the earlier studies the data sets only extended to ~20 Å so that when the nontronite expanded to greater than 19.5 Å (hydrated) the main 001 peak was only partially visible in the observed d-spacing range. The aim of the current work was to collect similar in situ diffraction data over a greater d-spacing range to observe more fully the movement of the main 001 reflection in order to better understand the changes taking place. This work was undertaken at the powder diffraction beamline of the Australian Synchrotron which was configured such that an upper d-spacing limit of ~34.5 Å could be achieved. Suggestions arising out of the previous work were confirmed along with additional information from testing of samples from the Source Clays Repository of The ClayMinerals Society. These results also show contradictory behavior of clays with the layer charge distributed over tetrahedral and octahedral sheets.

In Situ Observation of Strains during Lithiation of a Graphite Electrode

The mechanics and microstructure of electrodes are critical in determining the performance and durability of lithium-ion batteries, especially the new large format cells and packs developed for transportation applications. During battery operation, Li diffuses into and out of the electrode particles, causing microstructural changes and deformation-induced degradation. A variety of models have been proposed to interpret these mechanical and microstructural changes, but they have no direct experimental support. We report direct in situ measurements of the microstructural strain in a composite electrode during lithium insertion using a side-by-side cell geometry. The color variation in graphite with Li concentration creates lithium spatial maps. A digital image correlation analysis provides corresponding deformation and strain fields, displaying both dilation and contraction. Through a combination of experimental measurement and theoretical analysis, the unexpected contraction during lithiation is explained by the stiffening of graphite upon lithiation. The result confirms the change in modulus that we recently predicted. Quantification of local strains shows that an increased graphite crystallite volume during lithiation is accommodated primarily by a decrease in the composite (or particle) porosity. The change in porosity can substantially impact battery power; however, this effect has generally been ignored in cell performance models for lithium-ion batteries.

Notes on the application of the Matsui-Kitamura stent-graft for endovascular repair of abdominal aortic aneurysm

Abdominal aortic and left common iliac aneurysms in a 79-year-old man who had undergone Miles' operation for rectal carcinoma were treated with endovascular repair of an abdominal aortic aneurysm (EVAR), taking into consideration the age, surgical history, and wishes of the patient and his family. The Matsui-Kitamura stent-graft (MK-SG) was designed based on preoperative angiographic mapping. At EVAR, the right leg of the MK-SG was caught at the aortic bifurcation because of unexpected contraction of the MK-SG. To resolve the problem, the body of the MK-SG was dilated with a balloon, slightly lifted while being gradually shortened, and eventually successfully connected to the leg of the MK-SG. Made of nitinol mesh, the MK-SG is stable and flexible enough to make it one of the best stent-grafts for EVAR. A serious drawback, however, is the high contraction rate of the MK-SG itself. It is difficult to estimate the appropriate length of the stent-graft owing to unpredictable contraction. It is important to understand its characteristics and to carefully design and acquire sufficient skills in manipulating MK-SG.

Synthesis of 1,7-epoxycyclononanes and 1,8-epoxycyclodecanes by β-fragmentation reactions using LTA and I 2

The reaction of derivatives on C3 of 6-hydroxy-2,7-dimethyl-11-oxatricyclo[6.2.1.0 2,6]undecan-4-one with lead tetraacetate and iodine, gave, in a good yield, 1,7-epoxycyclononanes. These compounds are the result of a β-fragmentation at the level of C2–C6 respect to the tertiary hydroxyl group on C6, with an unexpected contraction from a ten to a nine-membered ring system, via a radical addition to the carbonyl group on C4. The treatment of precursors (non-functionalized on C3) with LTA and iodine produced again a β-fragmentation without any structural rearrangement, affording a typical 1,8-epoxycyclodecane system. The transformation of the carbonyl group on C4 into acetate avoided radical additions and rearrangements affording, in high yield, the corresponding cyclodecanes. By this methodology, either 1,7-epoxy-cyclononane or 1,8-epoxycyclodecane could be synthesized, in a good yield, from the same versatile precursor.

Study of insulator to metal transition in Rb4C60 by coherent and incoherent X-ray scattering under pressure

The equation of state (EOS) of Rb4C60 is determined by high-pressure X-ray diffraction measurements. We observe an abrupt jump in the compressibility of Rb4C60 between 0.5 and 0.8 GPa which is attributed to a structural phase transition preserving the tetragonal symmetry. Pressure effects on electronic density are studied by measuring Compton profiles below and above the transition. The ab initio calculation of the electronic structure is used to obtain theoretical equation of state, which agrees well with the experimental results. The calculations are used to quantitatively identify different contributions to the Compton profiles. In particular, we point out an unexpected contraction of the C-60 molecular volume under pressure which brings about significant effects on the electronic density of Rb4C60 compound. (c) 2006 Published by Elsevier Ltd.

In situpressure study ofRb4C60insulator to metal transition by Compton scattering

Compton scattering has been shown to be a powerful tool for studying the ground state electronic density in real materials. Using synchrotron radiation, we have studied pressure effects on Rb4C60 by measuring the Compton profiles below and above the insulator to metal transition at 0.8 GPa. The experimental results are compared with the corresponding calculated results, obtained from new ab initio energy band structure calculations. These results allow us to quantitatively evaluate contributions to the Compton profiles resulting from the contraction of the unit cell as well as from the contraction of the C60 molecule itself. In this paper, we point out an unexpected contraction of the volume of the C60 molecule, leading to a major effect on the electronic density of the Rb4C60 compound.

In situ observations of lattice expansion and transformation rates of α and β phases in Ti–6Al–4V

In situ X-ray diffraction experiments using synchrotron radiation were performed on Ti–6Al–4V samples to directly observe the α → β phase transformation during heating. These experiments were conducted at the Advanced Photon Source (APS) using a 30 keV synchrotron X-ray beam to monitor changes in the α and β phases as a function of heating time under different heating rates. The results were compared to computational thermodynamic predictions of the phase fractions versus temperature, providing information about the kinetics of the α → β transformation in Ti–6Al–4V. The measured transformation rates were shown to be consistent with a diffusion-controlled growth mechanism, whereby diffusion of V in the β-Ti phase controls the rate. Based on the X-ray diffraction data, real time measurements of the α and β phase lattice parameters were made. Dramatic differences were observed in the changes of the lattice parameters of the two phases during the transformation. These changes are believed to be due to the partitioning of V and its strong effect on the lattice parameter of the β phase. An unexpected contraction of the lattice parameter of the β phase was further observed during heating in the temperature range between 500 and 600 °C. The origin of this contraction is most likely related to the annealing of residual stresses created by the different thermal expansion behaviors of the two phases.

Interaction of H2O and NO2 with BaY Faujasite: Complex Contraction/Expansion Behavior of the Zeolite Unit Cell

In situ time-resolved X-ray diffraction in combination with the Rietveld method was used to study the contraction/expansion behavior of a BaY faujasite zeolite during dehydration and NO2 adsorption/desorption reactions. The adsorption of water and NO2 molecules induced a significant contraction of the zeolite unit cell. The unexpected contraction of the unit cell was closely related to the amount of water and NOx species (NO+, NO2, NO3-) inside the framework. The reaction H2O + NO2 → NO3- + H+ had a substantial effect on the structural properties of the BaY system. The NO3- groups produced a shift in the position of the Ba cations and a reduction in the zeolite unit cell.

Unexpected contraction of a zeolite framework upon isomorphous substitution of Si by Al

Isomorphous substitution of Si by Al in the framework of sodalites synthesized in ethylene glycol causes an unexpected contraction of the zeolite framework.

Structure Cristalline de NaAIAs2O7

We present a structural analysis of NaAlAs2O7, Mr = 311.81, monoclinic, P21/c, a = 6.9114(7), b = 8.1345(12), c = 9.5446(10) Å, β = 107.51(1)°, V = 511.74. Å3, Z = 4, dm = 4.02, dcal= 4.05 g/cm3, MoKα, λ = 0.7107 Å μ = 140.3 cm-1, F (000) = 146, R = 0.039, Rw = 0.038 for all the 1023 independent observed reflections. The structure of NaAlAs2O7 is compared to that of the MIMIII P2O7 form II diphosphates. The two structures are composed of the same building units, MIII O6 octahedra and X2 O7 (X = As or P) groups. The main difference is that the parts played by the X2O7 groups and the MIIIO6 octahedra, as also the stacking of the polyhedra, are exchanged in the two structures. The change is shown to be likely due to the length of the As-O-As bridge and makes it possible to account for the unexpected contraction of the a parameter in NaAlAs2O7 in spite of its being the lengthening direction of the X-O-X bridge.

Avulsion fractures of the tibial tuberosity in adolescents treated by tension band wiring

This study deals with the surgical treatment and the results of 7 avulsion fractures of the tibial tuberosity in adolescents. All the patients were treated in our department from 1977 to 1989. These are mainly athletic injuries accounting for less than 3% of all epiphyseal bones and they have not been widely reported in the orthopaedic literature. It is a different entity from Osgood Schlatter disease which is noted as a predisposing factor. The mechanism of injury consists of sudden, unexpected contraction in the quadriceps while the knee is being forcibly flexed. The closing physis of the tuberosity cannot resist the increased tensile forces and it is avulsed. Operative treatment was thought necessary for all our cases due to tibial tuberosity displacement and open reduction, internal fixation with tension-band technique was used. This lessens the need for immobilization at the joint following surgery.Functional results were very good and all the patients returned to their previous athletic activities.