Intrinsic Stiffness Research Articles

Continuum theory for elastic sheets formed by inextensible crossed elasticae

An equilibrium theory for elastic surfaces formed by two families of intextensible fibers is developed. This extends the work of Wang and Pipkin, which accounts for the intrinsic flexural stiffness of the fibers, to include intrinsic twisting resistance. The constituent fibers behave mechanically like spatial Kirchhoff rods. These are regarded as being continuously distributed on the surface and convected by the underlying surface deformation as inextensible material curves.

Intrinsic ankle stiffness during standing increases with ankle torque and passive stretch of the Achilles tendon.

Individuals may stand with a range of ankle angles. Furthermore, shoes or floor surfaces may elevate or depress their heels. Here we ask how these situations impact ankle stiffness and balance. We performed two studies (each with 10 participants) in which the triceps surae, Achilles tendon and aponeurosis were stretched either passively, by rotating the support surface, or actively by leaning forward. Participants stood freely on footplates which could rotate around the ankle joint axis. Brief, small stiffness-measuring perturbations (<0.7 deg; 140 ms) were applied at intervals of 4–5 s. In study 1, participants stood at selected angles of forward lean. In study 2, normal standing was compared with passive dorsiflexion induced by 15 deg toes-up tilt of the support surface. Smaller perturbations produced higher stiffness estimates, but for all perturbation sizes stiffness increased with active torque or passive stretch. Sway was minimally affected by stretch or lean, suggesting that this did not underlie the alterations in stiffness. In quiet stance, maximum ankle stiffness is limited by the tendon. As tendon strain increases, it becomes stiffer, causing an increase in overall ankle stiffness, which would explain the effects of leaning. However, stiffness also increased considerably with passive stretch, despite a modest torque increase. We discuss possible explanations for this increase.

Elastic Elements in a Wrist Prosthesis for Drumming Reduce Muscular Effort, but Increase Imprecision and Perceived Stress.

Recently, progress has been made in the development of mechanical joints with variable intrinsic stiffness, opening up the search for application areas of such variable-stiffness joints. By varying the stiffness of its joints, the resonant frequency of a system can be tuned to perform cyclical tasks most energy-efficiently, making the variable-stiffness joint a candidate element for an advanced prosthetic device specifically designed for the cyclical task of drumming. A prerequisite for a successful variable-stiffness drumming prosthesis is the ability of human drummers to profitably employ different stiffness levels for playing different beats. In this pilot study, 29 able-bodied subjects (20 drumming novices and 9 experts) wear a cuff on the forearm, to which a drumstick is connected using changeable adapters, consisting of several leaf springs with different stiffness and one maximally stiff connection element. The subjects are asked to play simple regular drum beats at different frequencies, one of which is the resonant frequency of the adapter-drumstick system. The subject's performance of each drumming task is rated in terms of accuracy and precision, and the effort is measured using questionnaires for the perceived stress as well as electromyography (EMG) for the muscular activity. The experiments show that using springs instead of the stiff connection leads to lower muscular activity, indicating that humans are able to use the energy-storing capabilities of the springs, or that muscular activity is reduced due to the lower mass of the springs. However, the perceived stress is increased and the novices' performance lowered, possibly due to a higher cerebral load for controlling the elastic system. The hypothesis that “matching the resonant frequency of the spring-drumstick system to the desired frequency leads to better performance and lower effort” is not confirmed. Possible explanations are discussed. In conclusion, a series-elastic element appears to lower the muscular effort of drumming, while a stiff connection appears to minimize the mental load and has a positive effect on the performance of drumming novices.

Defective boron nitride nanotubes: mechanical properties, electronic structures and failure behaviors

Due to their excellent physical and chemical characteristics, boron nitride nanotubes (BNNTs) are regarded as a complementary addition to carbon nanotubes. Pioneer studies have demonstrated that defects in carbon nanotubes are considered tools for tuning the physical properties of these materials. In the present work, investigation on the mechanical and electronic properties of pristine and defective BNNTs was performed using the density functional theory method. The analysis on the intrinsic strength, stiffness, and failure critical strain of different types of BNNTs was conducted systematically. The computing results showed that the intrinsic strength of BNNTs decreased linearly with the increased Stone–Wales (SW) defect density around the axis. The SW defect density along the axis played a minor role on the changing of mechanical properties of BNNTs. The BNNT with a B vacancy expressed higher intrinsic strength than that of the N vacancy model. The final failure of the pristine BNNTs was due to the fracture of the Type1 bonds under the mechanical strain. Defects like SW or vacancy are served as the initial break site of BNNTs. Applying strain or creating defects are both effective methods for reducing the band gap of BNNTs.

AT1 Receptor Antagonism Improves Structural, Functional, and Biomechanical Properties in Resistance Arteries in a Rodent Chronic Kidney Disease Model.

The renin-angiotensin system, in particular Angiotensin II (AngII), plays a significant role in the pathogenesis of hypertension in chronic kidney disease (CKD). Effects of chronic AT1 receptor antagonism were investigated in a genetic hypertensive rat model of CKD, the Lewis polycystic kidney (LPK) rat. Mixed-sex LPK and Lewis control rats (total n = 31) were split between treated (valsartan 60 mg/kg/day p.o. from 4 to 18 weeks) and vehicle groups. Animals were assessed for systolic blood pressure and urine biochemistry, and after euthanasia, blood collected for urea and creatinine analysis, confirming the hypertensive and renal phenotype. Mesenteric resistance vasculature was assessed using pressure myography and histology. Valsartan treatment improved vascular structure in LPK rats, increasing internal and external diameter values and reducing wall thickness (untreated vs. treated LPK: 53.19 ± 3.29 vs. 33.93 ± 2.17 μm) and wall-lumen ratios (untreated vs. treated LPK: 0.52 ± 0.09 vs. 0.16 ± 0.01, all P < 0.0001). Endothelium dysfunction, as measured by maximal response to acetylcholine (Rmax), was normalized with treatment (untreated vs. treated LPK: 69.56 ± 4.34 vs. 103.05 ± 4.13, P < 0.05), increasing the relative contributions of nitric oxide and endothelium-derived hyperpolarization to vasorelaxation while downregulating the prostanoid contribution. Biomechanical properties also improved with treatment, as indicated by an increase in compliance, decrease in intrinsic stiffness and alterations in the artery wall composition, which included decreases in collagen density and collagen/elastin ratio. Our results highlight the importance of AngII as a driver of resistance vessel structural, functional, and biomechanical dysfunction and provide insight as to how AT1 receptor blockade exerts therapeutic efficacy in CKD.

Load-Independent Systolic and Diastolic Right Ventricular Function in Heart Failure With Preserved Ejection Fraction as Assessed by Resting and Handgrip Exercise Pressure–Volume Loops

Although systolic right ventricular (RV) dysfunction has been shown to be a potent predictor for adverse outcomes in patients with heart failure with preserved ejection fraction (HFpEF), RV functional abnormalities in the course of the syndrome are not well characterized. We, therefore, sought to assess load-independent and load-dependent systolic and diastolic characteristics of RV function in stable outpatients with HFpEF. We invasively obtained RV and left ventricular pressure-volume loops in 24 HFpEF patients and 9 patients without heart failure symptoms with a conductance catheter during basal conditions and handgrip exercise. Transient preload reduction was used to extrapolate the RV end-systolic elastance and diastolic stiffness constant. HFpEF patients and controls showed similar left ventricular and RV dimensions and ejection fractions with elevated left ventricular filling pressures. In HFpEF patients, invasively determined load-independent RV contractility (P=0.04) and load-independent passive RV stiffness constant β (P<0.01) were elevated. Although RV relaxation and cardiac output were similar at baseline, HFpEF patients demonstrated a blunted increase in cardiac output under exercise (P=0.01) associated with prolonged RV relaxation (P=0.01), decrease in stroke volume (P<0.01), higher RV-filling pressures (P<0.01), and a marked increase in the end-diastolic pressure-volume relationship (P<0.01). In compensated stages of the HFpEF syndrome, systolic RV function is preserved, but diastolic abnormalities with intrinsic RV stiffness and prolonged RV relaxation are already present. Impaired diastolic RV reserve contributes to a blunted increase in cardiac output during exertion. Because impairments in diastolic function seem to be a biventricular phenomenon, RV diastolic dysfunction warrants further consideration when characterizing HFpEF patients. https://www.clinicaltrials.gov. Unique identifier: NCT02459626.

Determination of the region of the limiting states occurrence in RVS-20000 with the subsidence of the external bottom contour

The problem of the limiting states occurrence in the structures of a vertical steel tank is investigated in this work. To study the SSS of the metal structures of the object, the authors created a numerical model of the RVS-20000 tank in the ANSYS software complex. The model considers the maximum number of elements with their geometry and connections affecting the tank SSS under non-axisymmetric loading, including beyond the elasticity of steel. Dependences between the parameters of intrinsic stiffness of the VST are obtained. The results of the finite element analysis made it possible to develop a technique for assessing the technical condition of the structure with the development of irregular subsidence of the external bottom contour. The proposed technique can be used by both operating and design organizations in making managerial decisions regarding the repair of RVS-20000 subjected to the base subsidence.

Changes of intrinsic stiffness of the carotid arterial wall during the cardiac cycle measured by shear wave elastography in hypertensives compared to normotensives

ObjectiveBecause measurement of arterial stiffness is highly dependent on blood pressure (BP), methods independent of BP are required. Shear wave elastography (SWE, Supersonic Imagine, Aix-en-Provence, France) enables to assess local tissue stiffness by tracking the propagation of shear waves generated into the tissue using ultrafast imaging. This method has never been tested against classical Echotracking (Artlab, Esaote, Maastricht, NL) and carotid to femoral pulse wave velocity (cf-PWV, Sphygmocor, AtCor, Sydney, Australia).MethodsWe included 25 subjects, 14 normotensives (NT) and 11 essential hypertensives (HT), matched for age and sex. We optimized SWE algorithms for carotid wall tracking and shear wave group velocity calculation for the anterior (a-SWV) and posterior wall (p-SWV). 8 ultrasonic pushes were triggered at intervals of 200 ms to study the variations of stiffness during the cardiac cycle.Resultsp-SWV showed no association with carotid PWV, cf-PWV nor BP. Mean a-SWV over the cardiac cycle was strongly associated with carotid PWV measured by Echotracking (r = 0.56, p = 0.003) and cf·PWV (r = 0.66, p< 0.001). a-SWV strongly increased with BP level during the cardiac cycle (p < 10−6). Similar associations between a-SWV and BP were found in NT and HT although HT had higher values of a-SWV throughout all BP levels. However, when a common BP value (100 mmHg) was considered, no significant difference was found between NT and HT.ConclusionWe have demonstrated with a method independent of BP that the increased arterial stiffness in HT is entirely due to the BP increase. SWE seams a promising technique for assessing arterial stiffness.

The progress of studies on aqueous humor dynamics abnormality induced by trabecular meshwork and Schlemm canal endothelial cell senescence and its relation with glaucoma

Glaucoma is the second leading cause of blindness in the world next to cataract. Aging is a strong risk factor leading to elevated intraocular pressure (IOP). IOP is associated with aqueous humor circulation. Trabecular meshwork cells and Schlemm canal endothelial cells, which form the conventional outflow pathway, play an important role in maintaining the IOP. Cell senescence induces abnormalities of the aqueous humor dynamics, leading to elevated IOP. Trabecular meshwork cells cause increased intrinsic stiffness, autophagy dysfunction, abnormal expression of microRNA and mitochondrial dysfunction with senescence. The senescence of Schlemm canal endothelial cells decreases cell permeability and mechanotransduction and disrupts the endothelial nitric oxide synthase signaling pathway. The changes will increase aqueous humor outflow resistance and elevate IOP. This review discusses how cell senescence induces aqueous humor dynamics abnormalities and the relation with glaucoma. (Chin J Ophthalmol, 2017, 53: 868-873).

A Special Report on the NHLBI Initiative to Study Cellular and Molecular Mechanisms of Arterial Stiffness and Its Association With Hypertension

Large arteries (especially the aorta) lose elasticity and thicken with aging and as a consequence of other conditions, thus leading to central arterial stiffening and associated adverse effects on blood flow and pressure. Arterial stiffness can be defined and measured in different ways, at a local level or systemically. Increases in either the intrinsic (material) stiffness or net structural (combined geometric and material) arterial stiffness, or both, can increase the velocity at which the pressure pulse travels along the arterial tree and central pulse pressure, which can negatively impact downstream resistance vessels and organs (ie, heart, brain, and kidney). Clarifying temporal and causal relationships between arterial stiffening and hypertension was identified by NHLBI as an important gap of knowledge, with a potential for clinical translation. NIH (National Institutes of Health)-funded studies, more than half of them supported by the NHLBI (Online Figure), have investigated various aspects of arterial stiffening in humans and in experimental models. To enable a more focused research effort on this topic, NHLBI launched a Request for Applications (RFA) HL-10 -027, entitled Cellular and Molecular Mechanisms of Arterial Stiffening and Its Relationship to Development of Hypertension (R01). This initiative supported 11 R01 awards during 2010 to 2015 (Online Table II; cumulative ≈ $20 million dollars in total costs), which represented a significant component of the overall NHLBI investment in this field. Here, we report a summary of important scientific findings that resulted from this NHLBI-initiated research effort, constituting the basis of > 200 original research and review articles (Online Table II), some highlighted here, many conference presentations, and several patents . In humans, increased arterial stiffness, or loss of elastic compliance of large arteries, has been linked to an increased risk of myocardial infarction, heart failure, stroke, and kidney disease, among other conditions. Pulse wave velocity (PWV), …

Differential cell-matrix mechanoadaptations and inflammation drive regional propensities to aortic fibrosis, aneurysm or dissection in hypertension.

The embryonic lineage of intramural cells, microstructural organization of the extracellular matrix, local luminal and wall geometry, and haemodynamic loads vary along the length of the aorta. Yet, it remains unclear why certain diseases manifest differentially along the aorta. Toward this end, myriad animal models provide insight into diverse disease conditions-including fibrosis, aneurysm and dissection-but inherent differences across models impede general interpretations. We examined region-specific cellular, matrix, and biomechanical changes in a single experimental model of hypertension and atherosclerosis, which commonly coexist. Our findings suggest that (i) intramural cells within the ascending aorta are unable to maintain the intrinsic material stiffness of the wall, which ultimately drives aneurysmal dilatation, (ii) a mechanical stress-initiated, inflammation-driven remodelling within the descending aorta results in excessive fibrosis, and (iii) a transient loss of adventitial collagen within the suprarenal aorta contributes to dissection propensity. Smooth muscle contractility helps to control wall stress in the infrarenal aorta, which maintains mechanical properties near homeostatic levels despite elevated blood pressure. This early mechanoadaptation of the infrarenal aorta does not preclude subsequent acceleration of neointimal formation, however. Because region-specific conditions may be interdependent, as, for example, diffuse central arterial stiffening can increase cyclic haemodynamic loads on an aneurysm that is developing proximally, there is a clear need for more systematic assessments of aortic disease progression, not simply a singular focus on a particular region or condition.

A Sensitivity Analysis of an Inverted Pendulum Balance Control Model.

Balance control models are used to describe balance behavior in health and disease. We identified the unique contribution and relative importance of each parameter of a commonly used balance control model, the Independent Channel (IC) model, to identify which parameters are crucial to describe balance behavior. The balance behavior was expressed by transfer functions (TFs), representing the relationship between sensory perturbations and body sway as a function of frequency, in terms of amplitude (i.e., magnitude) and timing (i.e., phase). The model included an inverted pendulum controlled by a neuromuscular system, described by several parameters. Local sensitivity of each parameter was determined for both the magnitude and phase using partial derivatives. Both the intrinsic stiffness and proportional gain shape the magnitude at low frequencies (0.1–1 Hz). The derivative gain shapes the peak and slope of the magnitude between 0.5 and 0.9 Hz. The sensory weight influences the overall magnitude, and does not have any effect on the phase. The effect of the time delay becomes apparent in the phase above 0.6 Hz. The force feedback parameters and intrinsic stiffness have a small effect compared with the other parameters. All parameters shape the TF magnitude and phase and therefore play a role in the balance behavior. The sensory weight, time delay, derivative gain, and the proportional gain have a unique effect on the TFs, while the force feedback parameters and intrinsic stiffness contribute less. More insight in the unique contribution and relative importance of all parameters shows which parameters are crucial and critical to identify underlying differences in balance behavior between different patient groups.

Hyperconnected molecular glass network architectures with exceptional elastic properties

Hyperconnected network architectures can endow nanomaterials with remarkable mechanical properties that are fundamentally controlled by designing connectivity into the intrinsic molecular structure. For hybrid organic–inorganic nanomaterials, here we show that by using 1,3,5 silyl benzene precursors, the connectivity of a silicon atom within the network extends beyond its chemical coordination number, resulting in a hyperconnected network with exceptional elastic stiffness, higher than that of fully dense silica. The exceptional intrinsic stiffness of these hyperconnected glass networks is demonstrated with molecular dynamics models and these model predictions are calibrated through the synthesis and characterization of an intrinsically porous hybrid glass processed from 1,3,5(triethoxysilyl)benzene. The proposed molecular design strategy applies to any materials system wherein the mechanical properties are controlled by the underlying network connectivity.

Heterotopic Ossification after Arthroscopic Elbow Contracture Release

The excessive use of a radiaofrequency device in arthroscopic elbow release will result in an increased incidence of heterotopic ossification. This study investigates the prevalence and risk factors of heterotopic ossification (HO) in arthroscopic elbow release surgery. There were 101 elbows with arthroscopic release performed on 98 patients over the 5-year period from November 2011 to December 2015. They were divided into 3 groups. Group 1, elbow arthritis, included 46 elbows in 43 patients. Group 2, posttraumatic extrinsic elbow stiffness, included 23 elbows in 23 patients, and 32 elbows in 32 patients with intraarticular fractures and severe intrinsic contractures were in Group 3. Arthroscopic elbow release was performed under general anesthesia. In the postoperative period, x-ray or CT was followed up regularly to determine if there was HO, which was diagnosed when significant new calcifications were identified. The functional recovery was evaluated by comparing the range of motion and Mayo Elbow Performance Score (MEPS) pre and postoperatively in each group. Other complications were also assessed postoperatively. The patients’ mean age was 38.6 (range, 12–66) years old, with 57 males and 41 females. Mean follow-up was 21 (range, 4–56) months. HO developed in 25/101 (25%) elbows and 4 severe cases underwent repeat surgery. Group 1 patients were primarily arthritis and 3/46 (6.5%) elbows had minor HO on x-ray. In Group 2, 1/23 (4.3%) elbows had minor HO. However, in Group 3, 21/32 (65.6%) elbows developed HO, including 4 severe cases, 4 moderate cases and 13 minor cases. The average flexion– extension arc was improved from 93° to 126° in Group 1, 66° to 121° in Group 2, 46° to 91° in Group 3 at the last follow up. MEPS increased from 71.4 to 91.3 in Group 1, 65.6 to 93.5 in Group 2 and 52.3 to 80.6 in Group 3. In these severe intrinsic contractures cases, we routinely applied the radiofrequency device to create space for visualization and release, which was rarely used in Group 1 and 2. The occurrence of HO after arthroscopic elbow release for intrinsic posttraumatic stiffness was unexpectedly high. The predominant risk factor for the increased incidence of heterotopic ossification in this series was excessive use of radiofrequency, and this complication apparently impaired the otherwise predictable outcome.

Densification of the interlayer spacing governs the nanomechanical properties of calcium-silicate-hydrate

Calciuam-silicate-hydrate (C-S-H) is the principal binding phase in modern concrete. Molecular simulations imply that its nanoscale stiffness is ‘defect-driven’, i.e., dominated by crystallographic defects such as bridging site vacancies in its silicate chains. However, experimental validation of this result is difficult due to the hierarchically porous nature of C-S-H down to nanometers. Here, we integrate high pressure X-ray diffraction and atomistic simulations to correlate the anisotropic deformation of nanocrystalline C-S-H to its atomic-scale structure, which is changed by varying the Ca-to-Si molar ratio. Contrary to the ‘defect-driven’ hypothesis, we clearly observe stiffening of C-S-H with increasing Ca/Si in the range 0.8 ≤ Ca/Si ≤ 1.3, despite increasing numbers of vacancies in its silicate chains. The deformation of these chains along the b-axis occurs mainly through tilting of the Si-O-Si dihedral angle rather than shortening of the Si-O bond, and consequently there is no correlation between the incompressibilities of the a- and b-axes and the Ca/Si. On the contrary, the intrinsic stiffness of C-S-H solid is inversely correlated with the thickness of its interlayer space. This work provides direct experimental evidence to conduct more realistic modelling of C-S-H-based cementitious material.

PP.25.43] CHANGES OF INTRINSIC STIFFNESS OF THE CAROTID ARTERIAL WALL DURING THE CARDIAC CYCLE MEASURED BY SHEAR WAVE ELASTOGRAPHY IN HYPERTENSIVES COMPARED TO NORMOTENSIVES

Objective: The question whether arterial stiffness in hypertension is increased solely because of increased arterial pressure is not solved. Because measurement of arterial stiffness is highly dependent on measurement of blood pressure (BP), the development of methods independent of BP is necessary for clarifying this question. Shear wave elastography (SWE, Supersonic Imagine, Aix-en-Provence, France) is an ultrasound technique which enables to quantitatively assess local tissue stiffness by remotely generating transient shear waves into the tissue (push mode) and tracking their propagation using a very fast sampling rate (up to 10 kHz). The elastic modulus of the material is directly related to the speed of the shear waves, with no need of BP. This method has never been tested against classical echotracking (Artlab, Esaote, Maastricht, NL) and carotid to femoral pulse wave velocity (cf-PWV, Sphygmocor, AtCor, Sydney, Australia). Design and method: We included 25 subjects, 14 normotensives (NT) and 11 essential hypertensives (HT), matched for age and sex. We compared SWE to echotracking and cf-PWV. We optimized SWE algorithms for carotid wall tracking and shear wave group velocity calculation for the anterior (a-SWV) and posterior wall (p-SWV). 8 ultrasonic pushes were triggered at intervals of 200 ms in order to study the variations of stiffness during the cardiac cycle. Results: p-SWV showed no association with carotid PWV, cf-PWV nor BP. Mean a-SWV over the cardiac cycle is strongly associated with carotid PWV measured by Echotracking (r = 0.56, p = 0.003) and cf-PWV (r = 0.66, p < 0.001). a-SWV strongly increases with BP level during the cardiac cycle (p < 10–6). Similar associations between a-SWV and BP were found in NT and HT although HT had higher values of a-SWV throughout all BP levels. However, when a common BP value (100 mmHg) was considered, no significant difference was found between NT and HT, therefore showing that the wall intrinsic material stiffness is not increased in HT. Conclusions: We have demonstrated with a method independent of BP that the increased arterial stiffness in HT is entirely due to the BP increase. SWE appears as a promising technique for assessing arterial stiffness.

Branched Aramid Nanofibers

AbstractInterconnectivity of components in three‐dimensional networks (3DNs) is essential for stress transfer in hydrogels, aerogels, and composites. Entanglement of nanoscale components in the network relies on weak short‐range intermolecular interactions. The intrinsic stiffness and rod‐like geometry of nanoscale components limit the cohesive energy of the physical crosslinks in 3DN materials. Nature realizes networked gels differently using components with extensive branching. Branched aramid nanofibers (BANFs) mimicking polymeric components of biological gels were synthesized to produce 3DNs with high efficiency stress transfer. Individual BANFs are flexible, with the number of branches controlled by base strength in the hydrolysis process. The extensive connectivity of the BANFs allows them to form hydro‐ and aerogel monoliths with an order of magnitude less solid content than rod‐like nanocomponents. Branching of nanofibers also leads to improved mechanics of gels and nanocomposites.

Sensory contributions to stabilization of trunk posture in the sagittal plane

Trunk stabilization is required to control posture and movement during daily activities. Various sensory modalities, such as muscle spindles, Golgi tendon organs and the vestibular system, might contribute to trunk stabilization and our aim was to assess the contribution of these modalities to trunk stabilization. In 35 healthy subjects, upper-body sway was evoked by continuous unpredictable, force-controlled perturbations to the trunk in the anterior direction. Subjects were instructed to either ‘maximally resist the perturbation’ or to ‘relax but remain upright’ with eyes closed. Frequency response functions (FRFs) of admittance, the amount of movement per unit of force applied, and reflexes, the modulation of trunk extensor activity per unit of trunk displacement, were obtained. To these FRFs, we fitted physiological models, to estimate intrinsic trunk stiffness and damping, as well as feedback gains and delays. The different model versions were compared to assess which feedback loops contribute to trunk stabilization. Intrinsic stiffness and damping and muscle spindle (short-delay) feedback alone were sufficient to accurately describe trunk stabilization, but only with unrealistically low reflex delays. Addition of muscle spindle acceleration feedback or inhibitory Golgi tendon organ feedback yielded realistic delays and improved the model fit, with a significantly better model fit with acceleration feedback. Addition of vestibular feedback did not improve the model fit. In conclusion, muscle spindle feedback and intrinsic mechanical properties are sufficient to describe trunk stabilization in the sagittal plane under small mechanical perturbations, provided that muscle spindles encode acceleration in addition to velocity and position information.

Hesperidin reverses perivascular adipose-mediated aortic stiffness with aging

We tested the hypothesis that hesperidin would reverse age-related aortic stiffness, perivascular adipose (PVAT) mediated-arterial stiffening and PVAT advanced glycation end-products (AGE) accumulation. Aortic pulse wave velocity (aPWV) and intrinsic mechanical stiffness, two measures of arterial stiffness, were assessed in C57BL/6 mice that were young (6months), old (27–29months), or old treated with hesperidin for 4weeks. Old compared with young mice had increased aPWV (444±10 vs. 358±8cm/s, P<0.05) and mechanical stiffness (6506±369 vs. 3664±414kPa, P<0.05). In old mice hesperidin reduced both aPWV (331±38cm/s) and mechanical stiffness (4445±667kPa) to levels not different from young. Aortic segments from old animals cultured with (+) PVAT had greater mechanical stiffness compared to young (+) PVAT (6454±323 vs. 3575±440kPa, P<0.05) that was ameliorated in arteries from old hesperidin treated cultured (+) PVAT (2639±258kPa). Hesperidin also reversed the aging-related PVAT AGE accumulation (all, P<0.05). A 4-week treatment with the AGE inhibitor aminoguanidine reversed both the age-related increase in aPWV (390±7cm/s) and mechanical stiffness (3396±1072kPa), as well as mechanical stiffness in arteries cultured (+) PVAT (3292±716kPa) (all, P<0.05) to values not different from young. In conclusion, hesperidin ameliorates the age-related increase in aortic stiffness and the PVAT-mediated effects on arterial stiffening. Hesperidin also reversed PVAT AGE accumulation, where PVAT AGE were shown to promote aortic stiffness with aging.

Highly Flexible and Efficient Fabric-Based Organic Light-Emitting Devices for Clothing-Shaped Wearable Displays

Recently, the role of clothing has evolved from merely body protection, maintaining the body temperature, and fashion, to advanced functions such as various types of information delivery, communication, and even augmented reality. With a wireless internet connection, the integration of circuits and sensors, and a portable power supply, clothes become a novel electronic device. Currently, the information display is the most intuitive interface using visualized communication methods and the simultaneous concurrent processing of inputs and outputs between a wearer and functional clothes. The important aspect in this case is to maintain the characteristic softness of the fabrics even when electronic devices are added to the flexible clothes. Silicone-based light-emitting diode (LED) jackets, shirts, and stage costumes have started to appear, but the intrinsic stiffness of inorganic semiconductors causes wearers to feel discomfort; thus, it is difficult to use such devices for everyday purposes. To address this problem, a method of fabricating a thin and flexible emitting fabric utilizing organic light-emitting diodes (OLEDs) was developed in this work. Its flexibility was evaluated, and an analysis of its mechanical bending characteristics and tests of its long-term reliability were carried out.