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Legumes and cereals complement their nutritional quality and there is a need of convenience products made with these grains. The objectives of this study were to determine the rheological and functional properties of precooked red kidney bean (RKB) flours and their effect on viscoelastic properties of gluten free cake batter and cupcake quality including consumer acceptance. RKB flours were thermally processed by boiling at 100 °C (0, 20, 30 and 40 min) and drying at 80 °C (3 and 4 h). Rheological properties of cake batter containing 100% RKB flour were tested by creep-recovery and dynamic frequency tests. Batter of RKB flour boiled for 20 min was significantly stiffer with 100 times less deformable character compared to the control. Increase in batter modulus ranged from 2000 times elastic component (G′), 988 times viscous component (G″) and 1805 times complex viscosity (η*) at 20 min boiling. Drying did not have a significant effect on viscoelastic properties. Firmness and height of gluten free RKB cupcake were not affected by heat treatment. RKB gluten free cake after heat-moisture treatment had improved consumer acceptance scores compared to the control. Our findings showed that 20 min boiling and 3 h drying process is adequate for precooked RKB flour.

The wool content in textiles is a key quality index and the corresponding quantitative analysis takes an important position due to common adulterations in both raw and finished textiles. Conventional methods are maybe complicated, destructive, time-consuming, environment-unfriendly. Developing a quick, easy-to-use and green alternative method is interesting. The work focuses on exploring the feasibility of combining near-infrared (NIR) spectroscopy and several partial least squares (PLS)-based algorithms and elastic component regression (ECR) algorithms for measuring wool content in textile. A total of 108 cloth samples with wool content ranging from 0% to 100% (w/w) were collected and all the compositions are really existent in the market. The dataset was divided equally into the training and test sets for developing and validating calibration models. When using local PLS, the original spectrum axis was split into 20 sub-intervals. No obvious difference of performance can be seen for the local PLS models. The ECR model is comparable or superior to the other models due its flexibility, i.e., being transition state from PCR to PLS. It seems that ECR combined with NIR technique may be a potential method for determining wool content in textile products. In addition, it might have regulatory advantages to avoid time-consuming and environmental-unfriendly chemical analysis.

The present study substituted (a) casein (CR) and (b) casein and fat (CR + FR) simultaneously with cold water‐soluble (CWS) rice starch citrates and lactates to control functional characteristics of imitation cheese (IC). Rheological analysis for cheese confirmed the dominancy of elastic component (G′ > G″) and pseudoplastic behavior with flow behavior index less than 1. Lactic acid‐modified CWS displayed better structural alignment with progressive rise in frequency as evident by rise in G′. Meltability of CR cheese samples containing modified starches showed no significant difference with respect to control. Cohesiveness significantly increased, whereas adhesiveness showed no difference for CR cheese samples when compared with control. These distinctive properties provide a scientific approach to control stretching, rheological/textural properties, and meltability of imitation cheese (IC) by using precise ratio of casein and fat along with modified starches. PRACTICAL APPLICATIONS: Starches modified by safe chemicals were used to partially replace fat and casein simultaneously in IC. Therefore, the present study will lead to development of low‐cost cheese, which will ultimately generate higher revenues for industry. Also it will reduce load of calories while improving/retaining quality of cheese.

The pasting and rheological properties of waxy rice powder (WRP) with high-temperature baking (140–180 °C) and the fine structure of its starch were investigated. Rapid visco-analysis showed that the viscosity and breakdown value of baked WRP decreased obviously compared to its native counterpart, and this trend was greatly increased under higher temperature. Rheological analysis indicated that the baked WRP had relatively more elastic component compared to viscosity component but was less thixotropic than native WRP, suggesting the swelling of starch granules and the leaching of starch molecules were retarded when the WRP was baked at high temperature. Additionally, WRP was severely degraded and further re-associated and interacted with other granules during high-temperature baking. Changes in starch fine structure contributed to the alteration of pasting and rheological properties of WRP. These findings suggest that high-temperature baking induced structural changes of starch and thus reduced the viscosity of WRP.

The determination of aromatic compounds is of importance in many fields. Even if these compounds may be determined by molecular fluorescence and second-order calibration, the methods are relatively complex and require higher mathematics. Here is explored whether the reduction of the dimensions, i.e., transforming two-dimensional data to one-dimensional data followed by a special variable selection and calibration process, is feasible for this purpose. The present work investigated the feasibility of combining competitive adaptive reweighted sampling and elastic component regression for the direct evaluation of the spectra to quantify three components simultaneously. Model population analysis has also been performed. The results confirmed the feasibility of the procedure, which may serve as an alternative method to simultaneously determine aromatics.

The differences in viscoelastic properties of gluten from two very different wheat flours, a weak soft flour dough and a strong semolina dough, primarily caused by their gliadin and glutenin content including gliadin to glutenin ratio were studied. The doughs were subjected to oscillatory time sweep tests at small and large amplitudes as well as small and large frequencies. The gluten subunits (LMW, HMW glutenins and gliadins) tagged with specific fluorescent quantum dots with a distint excitation wavelength were imaged with confocal laser scanning microscopy and their distribution and interactions were measured. The quantitative imaging data was converted into networking data that included lacunarity, network area, and number of network junctions. This networking data was correlated with rheology. The two different dough systems showed different oscillatory behavior during time sweeps. The critical role of LMW glutenins in keeping the structural integrity of semolina doughs was demonstrated by a direct correlation between the non-linear elastic component ‘e3/e1’ of the dough and protein network parameters of LMW glutenins. It was also shown that gliadins and HMW glutenins co-localize and associate throughout rheological deformations of the dough. The disruption of the three gluten subunits are responsible for rheological breakdown of soft wheat flour dough, with gliadins influencing the breakdown of the network at higher amplitude deformations. This research presents a new method to analyze the microstructure of wheat doughs and new understanding of how the network structure of the dough subunits contribute and are correlated with fundamental rheological tests.

Two types of ovine whey powder, with different protein content, were added at increasing substitution rates to two types of semolina, one with strong and tenacious gluten and the other with weak and sticky gluten. For each dough the optimum mixing time and hydration level were calculated using the consistograph. The whey powder negatively affected the leavening volume of all doughs, at all percentages except the lowest one (5%), mainly because of its effects on the elastic component of gluten as measured with a stress relaxation test. Differences of the secondary structure of gluten proteins among samples were investigated by analyzing the amide I band in the Fourier transform infrared spectra of the dough. Weak and strong semolina showed a different relative percentage of α-helix, random coil, and β-sheet structures. The longer mixing times for dough formation when using semolina with strong gluten led to an increase in α-helices and random coils, which caused a worse leavening performance than the weak-gluten semolina.

Today's society shows a growing interest in healthy, safe and high nutritional quality food. Thus, in this paper sweet orange marmalades have been developed using healthy sweeteners (tagatose and oligofructose) in different proportions. Analyses of Brix, pH, moisture, water activity, antioxidant capacity, optical and rheological properties have been carried out, initially and after 45 days of storage. Microbiological analyses have also been performed to determine their stability. Furthermore, a sensorial assessment has been conducted to find out acceptance of these new orange marmalades by consumers. The results showed that the highest proportion of oligofructose contributed to improve the initial antioxidant capacity of marmalades. The marmalade with the same proportions of oligofructose and tagatose was more consistent and showed a further increase in the elastic component over time. All marmalades had a similar appearance, but oligofructose reduced L*. Finally, orange marmalades made with healthy sweeteners were better scored. Practical Applications The development of new healthier marmalades offers new alternatives to the conventional ones not only to prevent caries and obesity but also to provide functional features associated with the use of tagatose and oligofructose as sweeteners. However, not always it is possible to replace traditional components by others and that is why it is so important to assess their technological influence. In this study, the viability of the use of both sweeteners to prepare orange marmalades has been checked.

Summary The viscoelastic behaviour and texture profile of gels composed of the high methoxyl pectin in hawthorn (HMPH) were studied, and these gels were compared with commercial citrus gels (HMPC). The values of G′ (elastic component) for the HMPH and HMPC gels (1% pectin and pH 3.0) were 2567 and 1177 Pa, respectively, and the values of G″ (viscous component) were 494 and 253, respectively. Because G′ > G″, both of these gels exhibit viscoelastic solid behaviour with predominant elastic characteristics. The viscoelastic behaviours of the gels were analysed using the Burger model. The texture analysis demonstrated that the hardness of the HMPH gels was almost 10-fold higher than that of the HMPC gels. In addition, the gumminess and chewiness of the HMPH gels were 31.2- and 46.1-fold higher than those of the HMPC gels, respectively. These results could likely contribute to the utilisation of HMPH pectins.

Hydroxyl sulfobetaines with hexadecyl-, octadecyl-hydrophobic chain and an industrial product hydroxyl sulfobetaine were synthesized from analytical-grade and industrial-grade tertiary amine, respectively. The dilational properties and surface tension of the three surfactants at the water-air interface were investigated by drop shape analysis and ring method. The influences of oscillating frequency and bulk concentration on dilational properties were explored. The experimental results show that the dilational module of octadecyl-hydroxyl sulfobetaine was higher than hexadecyl hydroxyl sulfobetaine and the dilational elastic component of the three surfactants were higher than dilational viscous component. Furthermore, the dilational elastic component of mixed surfactant system shows two maxima in a lower concentration than that of single surfactant system. As a result, the surface tension of mixed surfactant system reaches to minimum value in a lower concentration compared with single surfactant system. Th...

The purpose of this study was to examine the effects of a doublet stimulus evoked during isometric submaximal contractions on the electromechanical delay (EMD). Twenty-three healthy individuals performed isometric step contractions ranging from 10 to 70% maximal voluntary contraction (MVC) with a doublet stimulus applied during the contractions. A 2-way repeated-measures analysis of variance (gender [male vs. female] x contraction intensity [10% vs. 20% vs. 30% vs. 40% vs. 50% vs. 60% vs. 70% MVC]) was used to analyze the EMD. The EMD at 10% was significantly less than at 30% (p = 0.022), 40% (p = 0.044), 50% (p = 0.012), 60% (p = 0.041), and 70% MVC (p < 0.001). In addition, the EMD at 70% MVC was significantly higher than at 20% (p = 0.002), 30% (p = 0.006), 40% (p = 0.009), and 50% MVC (p = 0.021). The EMD is the time difference between muscle activation and the onset of muscle force production, with the stretching of the series elastic component (SEC) as the major contributor. A doublet stimulus applied during an isometric contraction minimizes the effects of the SEC during the interpolated twitch technique. Therefore, when the SEC is minimized, the EMD may be lengthened because of mechanisms associated with the excitation-contraction coupling at higher contraction intensities. The EMD measurement, produced with a doublet stimulus, could potentially be a useful tool to examine the effects of fatigue, exercise, stretching, and so on, on the excitation-contraction coupling during various force levels. However, future research is needed to further elucidate the mechanisms that result in a lengthening of the EMD under these conditions

The deformation behavior of thick Al wires and the expansion behavior of the bond area during ultrasonic wedge bonding to Al­Si, Si and SiO2 substrates were measured simultaneously in detail with a high-speed measuring system. The deformation of the wire by the application of the bonding force is completed immediately. The deformation restarts by the application of the ultrasonic vibration. The deformation induced by applying the bonding force consists of only elastic component, whereas that by ultrasonic vibration consists of only plastic component. The Al wire is not work-hardened by the plastic deformation during application of ultrasonic vibration. The adhered area expands to the direction perpendicular to the ultrasonic vibration. The evolution of the wire deformation behavior and the expansion of the adhered area show an intimate correlation with each other. [doi:10.2320/matertrans.MD201210]

The influence of overweight, as a precursor to obesity, was analyzed on the elastic properties of the triceps surae. Based on body mass index (BMI), children (9 years ± 4 mo) were classified as control (CON; n = 23; BMI −1SD>Z scoreZ scoreMT-Torque) or stiffness-EMG (SIMT-EMG) relationships and 2) passive stiffness from the intercept point with the ordinate. Finally, the SEC active (α0) and passive fractions (Cpassive) were separated as described by Morgan (Am J Physiol, 1977), using alpha-torque (α0-Torque,Cpassive-Torque) or alpha-EMG (α0-EMG,Cpassive-EMG) relationships. No significant differences in SIMT-Torqueor α0-Torquewere observed between OW and CON. SIMT-EMGor α0-EMGvalues were significantly different between OW and CON, which indicate an increase in MT stiffness. In all cases, passive stiffness (Kp, Cpassive-torque, Cpassive-EMG) was significantly greater in OW but independent of the activation capacities. These results indicate that a weight-related additional loading of the MT structures in OW children caused the MT system to response accordingly to the functional demand, i.e., higher stiffness of the MT structures due to a concomitant increase in the stiffness of the SEC passive and active fraction. This study also reveals that possible differences in the activation capacities influence the determination of MT stiffness of the SEC active fraction.

Flexible polyethylene foam is used in many engineering applications. It exhibits nonlinear and viscoelastic behavior which makes it difficult to model. To date, several models have been developed to characterize the complex behavior of foams. These attempts include the computationally intensive microstructural models to continuum models that capture the macroscale behavior of the foam materials. In this research, a nonlinear viscoelastic model, which is an extension to previously developed models, is proposed and its ability to capture foam response in uniaxial compression is investigated. It is hypothesized that total stress can be decomposed into the sum of a nonlinear elastic component, modeled by a higher-order polynomial, and a nonlinear hereditary type viscoelastic component. System identification procedures were developed to estimate the model parameters using uniaxial cyclic compression data from experiments conducted at six different rates. The estimated model parameters for individual tests were used to develop a model with parameters that are a function of strain rates. The parameter estimation technique was modified to also develop a comprehensive model which captures the uniaxial behavior of all six tests. The performance of this model was compared to that of other nonlinear viscoelastic models.

In this work, the rheometrical behaviour of Tarocco orange fruit was assessed via stress–relaxation testing under constant engineering strain (e z) in the range of 5–20% of the initial fruit height, each test being prolonged for 15 min and replicated 20 times. The time course of the experimental dimensionless relaxation modulus (G*) was typical of a viscoelastic solid and was reconstructed by considering two Maxwell elements in parallel to an elastic spring element. In a more restricted e z range (i.e. 5–10%), the dimensionless viscoelastic constants (A i) were found to be approximately constant, the elastic component responsible for the equilibrium residual stress representing about 42% of the initial relaxation modulus. After any orange fruit had been submitted to stress–relaxation testing and decompressed for 5 min, it exhibited a practically negligible mass loss (0.04 ± 0.03%) and a permanent volume contraction rising from 1.7 ± 1.0% to 3.0 ± 0.9% as e z was increased from 5% to 10%. Thus, by tasting the orange fruit firmness at e z ≤5%, fruit response, being of the viscoelastic type, is expected to give rise to nearly irrelevant deformations.

A method has been developed for forecasting stress relaxation in polypropylene film filaments, which is based on linear viscoelasticity. The elastic recovery has been examined for polypropylene (PP) film filaments, which is related to stress relaxation processes of various durations. The recovery curves in semilogarithmic coordinates are characterized by initial and final asymptotic levels, and also by an S-shaped elastic component of the process, an important characteristic of which is the relaxation time. The recovery parameters are complicated and are nonlinearly dependent on the given level of strain and the duration of the direct relaxation. A method is proposed for the analytic description and forecasting of elastic recovery in PP film filaments on the basis of the parameters of the preceding stress relaxation: in accordance with the duration of the direct relaxation and the given level of stretching.

The purpose of this study was to examine the force-velocity characteristics of colonie muscle and to determine whether these factors contribute to regional specialization of the colon observed in adult Fischer rats. Four measurements were obtained from circular colon muscle strips: maximum shortening velocity, a reflection of crossbridge cycling rate; extension of the parallel elastic component, a measure of passive muscle properties of relaxed muscle; the series elastic component, a measure of passive muscle properties of contracted muscle; and peak isometric force, which is equal to the product of the number of activated crossbridges and the strength of individual crossbridges. Muscle length (L) was expressed in terms of the length of optimal tension development (Lo). Peak isometric force and maximum shortening velocity were 848.9 ± 114.7 g/cm2 and 0.082 ± 0.012 Lo/s for muscle strips from the proximal colon, and 948.0± 138.2 g/cm2 and 0.083 ± 0.014 Lo/s for muscle strips from the distal colon. Shortening velocity, isometric force, and load extension properties of the parallel elastic component and the series elastic component are similar in proximal and distal rat colon. This suggests that regional specialization is not determined at the myofibril level but is most likely determined by extrinsic regulatory factors at the neural or receptor level.

The influence of sucrose on thermal and rheological properties of tapioca starch (TS)–tamarind seed xyloglucan (XG) mixtures was investigated. Rapid visco-analysis profiles of 5% w/w TS/XG dispersions at different mixing ratios revealed that peak and final viscosities increased with increasing sucrose and XG contents. Loss tangent of each mixing ratio of TS/XG pastes determined from dynamic rheometry exhibited a lower value with increasing sucrose, suggesting solid-like properties contributed from the dissolved sucrose in the systems. Gelatinization temperatures of 25% w/w TS/XG at mixing ratios of 10/0 and 9/1 increased with increasing sucrose content whereas the gelatinization enthalpy of pastes increased in the presence of high sucrose concentration. Sucrose increased the stiffness and hardness of the 25% w/w TS/XG gels (mixing ratios of 10/0, 9.5/0.5 and 9/1) from the compression test. These results suggest that sucrose delays the gelatinization of TS and XG mixtures and strengthens the gels by increasing the elastic component.

An oscillatory capillary rheometer was used to investigate visco-elastic properties of xanthan and locust bean gum (LBG) blends in dilute solution. Gums were evaluated for intrinsic viscosity and the elastic component. Molecular conformation of the complex of xanthan–LBG was assessed by the power law and the Huggins equations. A 60% xanthan–40% LBG blend exhibited the strongest attraction between xanthan and LBG molecules as evidenced by a greater intrinsic viscosity, the polymer miscibility coefficient α, the elastic component, and a positive Huggins coefficient Km. The power-law model was successfully applied to predict the molecular conformation of xanthan and LBG alone in dilute solution and was exhibited as rod-like and random coil conformation. The power-law coefficient b increased as the LBG fraction increased in the blends, suggesting a more flexible xanthan–LBG complex dependent on LBG.

Tempering has been shown in literature to preserve head rice yield after heated air drying. Most reported tempering work was done adiabatically at a temperature below that for rice drying. In this study, the effect of a tempering temperature above that for rice drying on the whole kernel percentage was investigated. High-temperature tempering is an effective way to preserve the whole kernel percentage for rice dried at a raised temperature (e.g., 60°C) at which head rice yield would otherwise incur a pronounced reduction without tempering. Tempering helped relax the strains inside a rice kernel induced by internal stresses developed during the drying process. The strains had two components (elastic component and viscous component) due to the viscoelasticity of rice kernels. The reduction of moisture content gradients inside a rice kernel during tempering helped eliminate the elastic component of the strains due to the elasticity of the rice kernel. Results showed that to effectively eliminate the...

The sol–gel transition of iota carrageenan and pectin is followed by measuring the evolution of ultrasonic velocity of a compressional wave at a frequency of 500 kHz. Measurements are performed as a function of temperature, from about 90 to 20 °C. Results are compared to those obtained in rheology in oscillatory conditions. It is shown that the ultrasonic velocity is sensitive to the sol–gel transition when going from a viscous to a “solid-like” state with a large elastic component. However, the method fails when the transition occurs gradually to give a weak elastic gel.

The effect of adding dextrin or dried whole egg on the rheological properties of raw coating batters and on the batters' textural properties immediately after final frying of the battered product and after some time had elapsed were studied. The flow behaviour of the batters was strongly dependent on working temperature (15–40 °C), and both dextrin addition and egg addition altered the behaviour slightly. Both hydrocolloids showed a viscoelastic behaviour with a clear elastic component, more evident at higher temperatures. Dextrin produced a batter coating with a crispier, more fragile texture, and this crispness was retained longer than in the case of the egg-containing batters, which showed a softened texture 30 min after frying.

Sodium dodecyl sulphate (SDS) and sodium tripolyphosphate (STP) act to remove stained pellicle from dentition and loosen deposits on tooth surfaces that may become cariogenic over time. This study investigated how SDS and STP impact the salivary pellicle adsorbed onto hydroxyapatite and silica sensors using a dual polarisation interferometer and a quartz-crystal microbalance with dissipation. After the pellicle was exposed to SDS and STP the remaining pellicle, although weaker, due to the loss of material, became less dense but with a higher elastic component; suggesting that the viscous component of the pellicle was being removed. This would imply a structural transformation from a soft but dense structured pellicle, to a more diffuse pellicle. In addition, the majority of proteins displaced by both SDS and STP were identified as being acidic in nature; implying that the negatively charged groups of SDS and STP may be responsible for the displacement of the pellicle proteins observed.

Flexibility, or softness, is crucial for protein function and consists of a conformational component, involving jumps between potential wells, and an elastic component, involving fluctuations within the wells. Combining molecular dynamics simulation with incoherent neutron scattering and light scattering measurements on green fluorescent protein, we reveal a relationship between the intrawell fluctuations and elastic moduli of the protein. This finding leads to a simple means of experimentally separating the conformational from the elastic atomic displacements.

The aim of this work was to assess the effects of calcium, fat and total solids on the rheology of a model soft cheese. Several batches of reconstituted skim milk with 9, 12 and 15% w/v total solids and reconstituted whole milk with 12, 15 and 18% w/v total solids were used to make a soft stranded cheese whose rheological characteristics, G' (storage modulus or elastic component) and G (loss modulus or viscous component), were measured using an RTI Stress Controlled Rheometer (RTI). All factors investigated had a significant effect on the rheology of the soft cheese ; however, they affected the rheological parameters differently, suggesting that the structural changes are not a result simply of the concentration of material in solution.

The Western diet, often characterized by excessive intakes of simple highly refined sugars and refined oils high in saturated fats, is leading to numerous deleterious health implications, resulting in an epidemic of diet-related diseases. In an attempt to curb these associated epidemics, governments, industries, and organizations are limiting the use of trans and saturated fats in foods while trying to maintain and often increase the quantities of unsaturated lipids such as flax and fish oils. However, these compounds do not provide an elastic component to the food texture which is not only desirable but, indeed, also required. Lipid replacers, which provide an elastic textural component to the unsaturated lipids or the aqueous phase, are becoming central in the development of new healthy foods. Further developments require a quest for new lipid substitutes by either rational molecular design or serendipitous explorations. In addition, the effects of processing and ingredient technology on the molecular assembly and supramolecular structures created the need to be better understood to tailor the physical properties of these networks.

Retinopexy may be produced by either of two mechanisms following transpupillary irradiation of the retina with the Nd:YAG laser. Which of these mechanisms is operative will depend on the degree of disruption produced within the elastic component of Bruch's membrane. Small defects in the elastic component of Bruch's membrane are soon completely bridged by regenerated retinal pigment epithelium (RPE) cells. However, there is a risk of subretinal neovascularization in such defects. Large defects in the elastic component of Bruch's membrane are not completely bridged by regenerating RPE cells before proliferating Muller cells invade this region and spread from it, mushroom-like, within the choroid. In this case subretinal neovascularization does not occur. In the former instance (small defects) retinopexy is achieved by a process of interdigitation between the microvilli of Muller and RPE cells; and in the latter (large defects) via a press-stud-like anchorage of Muller cells within the choroid. It has not yet been established whether these two retinopexy phenomena, observed after irradiation of rabbit retinas, occur in the same way in man.

6 pages - sous presse dans Comptes Rendus Mécanique; A thermographic analysis of heat sources accompanying the deformation of PMMA and PC polymers revealed several possible ways of introducing the thermoelastic coupling effects in the modelling. Therefore we used two basic linear viscoelastic models in which an elastic component was replaced by a thermoelastic branch. This Note highlights the practical interest of our approach for describing variations in thermoelastic sources during pulsating tensile testing of PMMA and PC samples L'analyse thermographique des sources de chaleur accompagnant la déformation des polymères PMMA et PC nous a conduit à introduire de plusieurs façons possibles les effets de couplage thermoélastique dans la modélisation. Pour cela, nous avons utilisé deux modèles viscoélastiques linéaires élémentaires dans lesquels un composant élastique a été remplacé par une branche thermoélastique. La Note montre l'intérêt pratique d'une telle approche pour décrire l'évolution des sources thermoélastiques du PMMA et du PC lors d'essais de traction ondulée.

The purpose of this study was to choose between two popular models of skeletal muscle: one with the parallel elastic component in parallel with both the contractile element and the series elastic component ( model A), and the other in which it is in parallel with only the contractile element ( model B). Passive and total forces were obtained at a variety of muscle lengths for the medial gastrocnemius muscle in anesthetized rats. Passive force was measured before the contraction ( passive A) or was estimated for the fascicle length at which peak total force occurred ( passive B). Fascicle length was measured with sonomicrometry. Active force was calculated by subtracting passive ( A or B) force from peak total force at each fascicle or muscle length. Optimal length, that fascicle length at which active force is maximized, was 13.1 ± 1.2 mm when passive A was subtracted and 14.0 ± 1.1 mm with passive B ( P < 0.01). Furthermore, the relationship between double-pulse contraction force and length was broader when calculated with passive B than with passive A. When the muscle was held at a long length, passive force decreased due to stress relaxation. This was accompanied by no change in fascicle length at the peak of the contraction and only a small corresponding decrease in peak total force. There is no explanation for the apparent increase in active force that would be obtained when subtracting passive A from the peak total force. Therefore, to calculate active force, it is appropriate to subtract passive force measured at the fascicle length corresponding to the length at which peak total force occurs, rather than passive force measured at the length at which the contraction begins.

The production of work by the contractile component (CC) and the storage and release of work in the elastic structures that act in series (the series elastic component, SEC) with the contractile component were measured using white muscle fibres from the dogfish Scyliorhinus canicula. Heat production was also measured because the sum of work and heat is equivalent to the energy cost of the contraction (ATP used). These energy fluxes were evaluated in contractions with constant-velocity shortening either during stimulation or during relaxation. The muscle preparation was tetanized for 0.6 s and shortened by 1 mm (approximately 15 % of L0) at 3.5 or 7.0 mm s−1 (approximately 15 or 30 % of V0), where L0 is the muscle length at which isometric force is greatest and V0 is the maximum velocity of shortening. In separate experiments, the stiffness of the SEC was characterized from measurements of force responses to step changes in the length of contracting muscle. Using the values of SEC stiffness, we evaluated separately the work and heat associated with the CC and with the SEC. The major findings were (1) that work stored in the SEC could be completely recovered as external work when shortening occurred during relaxation (none of the stored work being degraded into heat) and (2) that, when shortening occurred progressively later during the contraction, the total energy cost of the contraction declined towards that of an isometric contraction.

1. The time course of cross-bridge detachment-attachment following a step stretch was determined in single frog muscle fibres (at 4 degrees (1 and 2.1 microns sarcomere length) by imposing, under sarcomere length control by a striation follower, test step releases of various amplitudes (2-13 nm per half-sarcomere) at successive times (4-55 ms) after a conditioning stretch of approximately 4 nm per half-sarcomere. 2. The comparison with the control tension transients, elicited by releases not preceded by the conditioning stretch, shows that, early after the conditioning stretch, the quick tension recovery following small releases is depressed and the quick tension recovery following large releases is potentiated. Both effects are expected as a consequence of the strain produced in the cross-bridges by the conditioning stretch. 3. These effects disappear and the tension transient is reprimed, indicating substitution of freshly attached cross-bridges for strained cross-bridges, with a time constant of approximately 10 ms. 4. A novel multiple-exponential equation, based on the hypothesis of complete substitution of freshly attached cross-bridges for the cross-bridges that underwent the stretch, has been used to fit the whole tension transient following step stretches of different sizes (2-6 nm per half-sarcomere). For a stretch of 4 nm, the time constant of the exponential process responsible for cross-bridge detachment (tau d, 9.3 ms) almost coincides with the time constant of repriming as measured by the double-step experiments. The time constant of the exponential process representing the cumulative effects of attachment and force generation (tau 3) is 13.6 ms. 5. For stretches of different sizes the amount of quick tension recovery attributable to the reversal of the working stroke elicited by the stretches is estimated by subtracting, from the original tension transient, the contribution to tension recovery due to detachment-attachment of cross-bridges as estimated by the multiple-exponential analysis. Following this calculation, the structural change in the myosin heads responsible for the reversal of the working stroke can be 2 nm at maximum, suggesting that the elastic component in the cross-bridges is at least twice as rigid as previously thought.

1. The tension and sarcomere length responses induced by ramp stretches (amplitude 1-3% of initial fibre length (Lzero) and speeds of 0.01-12 Lzero s-1) were examined, at 10 degrees C and sarcomere lengths of approximately 2.7 microns, in resting intact muscle fibre bundles isolated from the soleus (a slow muscle) and extensor digitorum longus (a fast muscle) of the rat. 2. In both fibre types, the tension response to moderately fast ramp stretches consists of a viscous, a viscoelastic and an elastic component. At low stretch velocities, where the viscous component is very small, the tension response consists of only the viscoelastic and elastic components. 3. The viscosity coefficient (mean +/- S.E.M., 2 +/- 0.01 kN s m-2, n = 12) and the relaxation time of the viscoelasticity (44 +/- 2 ms, n = 12) of the slow muscle fibres were significantly larger than those of the fast muscle fibres (0.8 +/- 0.1 kN s m-2 and 11 +/- 1 ms, respectively, n = 20). 4. The relaxation time, in either fibre type, is too long for the viscoelasticity to be due to rapidly cycling, weakly attached cross-bridges. Moreover, the tension components increased with sarcomere length and were insensitive to 5-10 mM 2,3-butanedione 2-monoxime (BDM), which inhibited active contractions. 5. The possibility that the fast-slow fibre differences may reflect differences in myoplasmic viscosity and connectin (titin) isoforms (in their gap filaments) is discussed.

The effects of exercise training on mechanical properties and fibre type transitions have been investigated in rat soleus muscle. The exercise was a repetition of stretch-shortening cycles. A method of dual controlled releases was applied to obtain tension/extension curves, which characterize the elastic behaviour of the series elastic component (SEC), and the force/velocity relationship characterizing the contractile elements. Other contractile measurements included: contraction time (tc), half-relaxation time (t1/2) and twitch/tetanus ratio (Pt/Po). Additionally, the muscle fibre type composition was determined by a classical histochemical method. A 12-week period of training induced a significantly higher percentage of fast-twitch fibres and a lower percentage of slow-twitch fibres (P

Heavy-load resistance exercise is not normally associated with stretch shortening muscle activation. Rapid lengthening, and a decreased period of time between lengthening and shortening phases of contraction (amortisation phase) has been associated with increased energy transfer from passive muscle structures (series elastic component, SEC), and gains in muscle efficiency during stretch shortening muscle activation. In this investigation, we sought to determine the effect of limb velocity on the amortisation phase and electromyographic (EMG) activity during heavy load (85%1RM) resistance exercise. Twelve healthy males performed 6RM unilateral elbow flexion-extension exercise during; rapid lengthening-shortening, rapid shortening and slow lengthening-shortening muscle activation. The amortisation phase and velocity of lengthening and shortening were determined using a shaft encoder and muscle activity was recorded at the biceps brachii using intramuscular and surface EMG. A decrease (P

A synthetic patch made from tropoelastin, an elastic component of skin and arteries, can help repair damaged tissue

Fig. 1. Schematic drawing of Voigt's model. SEC::: series elastic component; CE ::: contractile element; PEC ::: parallel elastic component. Importance of Maximal Shortening Capacity of Airway Smooth Muscle Because of the nonspecificity of the increased contractile response of antigen-sensitized airway smooth muscle (SASM), the idea has developed that the primary cause of allergic bronchospasm resides in the contractile apparatus of the SASM (1). In 1979 we studied this possibility and reported (2) that in the ovalbumin-sensitized SASM, both the capacity to shorten (~lmax) and the maximal velocity of shortening (V0) were significantly greater than in the control airway smooth muscle. Interestingly, maximal isometric tetanic tension (Po) remained normal in the SASMs that had been obtained from 2-month-old pups. We concluded that Po is a poor and tardy index of altered contractility. The important finding emerging from this study was the increased ~lmax because it represented the important in vitro analogue to in vivo bronchospasm. It indicated that elucidation of bronchospasm must necessarily focus on mechanisms controlling extent of shortening. Although V0 also increased, suggesting that changes had occurred in the myosin molecule and its enzymatic properties, these did not relate directly to allergic bronchospasm. Recently, we conducted studies (3) on tracheal smooth muscle (TSM) from rats with congenitally hyperreactive airways and obtained similar results. We now describe the results of studies we have reported in the past (4) that deal with

Rheology of soya oil-water emulsions in the linear region has been studied. The viscoelastic response consisted of three contributions. There was a purely elastic component, a purely viscous component and a contribution due to the retarded compliance. Emulsions became more viscous and elastic with increasing soya oil concentration. Sharp changes in rheology were observed as the concentration approached the random close packed limit. There was also a marked increase in zero-shear viscosity. Breakdown of coagulation structure was observed as the shear stress was increased into the non-linear region. The rheological behaviour of the emulsions in the linear region could be adequately described by the generalized Kelvin-Voigt model.

SASAKI, H., HOPPIN, F.G., Jr. and TAKISHIMA, T. Effect of Duration of Stimulation on Mechanical Properties of Trachealis Muscle. Tohoku J. exp. Med., 1986, 150 (3), 259-271-We have studied the effect of duration of stimulation on the dynamic behavior of isolated dog trachealis muscle topically contracted by alternating current or carbachol. With the muscle contracted quick stretch and quick release maneuvers were performed. The force-length curves during the quick maneuvers were similar for both methods of stimulation and regardless of the duration of stimulation. This behavior is consistent with an undamped passive series elastic component. The plateaux of force preceding these quick maneuvers were also similar. Isometric stress relaxations after quick stretch were similar. However, after quick release, isometric stress recovery and isotonic shortening velocity were more rapid with alternating current stimulation than with carbachol, and both isometric stress recovery and isotonic shortening velocity decreased with increasing duration of stimulation by either means of stimulation. We conclude that the difference in velocity of shortening is not due to the different method of stimulation but rather to the duration of stimulation. Active respiratory smooth muscle may show different dynamic properties depending on the duration of stimulation but not on the differences in means of stimulation.

Flow irregularities have been visually observed in solutions of polyacrylamide of high molecular weight on shear in a cone-and-plate rheometry (gap angle 2.3°). This anomalous flow was found to depend on molecular weight, concentration, and solvent. The onset of flow irregularities were generally at shear rates < 5 sec−1. A dimensional analysis shows that the elastic component of the fluid is responsible for the anomalous flow. The onset of flow irregularities has been predicted from measurements of recoverable strain as a function of shear stress.

Segments of abdominal aorta from spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto (WKY) rats (20-25 weeks) were compared with respect to force production and dynamic mechanical properties. The preparations were mounted in vitro for determination of optimal length (lo) for active force, and then maximally stimulated (high-K+ solution, 10 mm Ca2+, 10(-5) m noradrenaline), and fixed for electron microscopy. Muscle cellular volume per mm vessel wall was significantly (p less than 0.01) higher in SHR (0.14 +/- 0.009 mm3, n = 7) compared to WKY (0.11 +/- 0.004 mm3, n = 7). Unchanged cell length and unaltered cross-sectional area (17 micrometers2) of nucleus containing cell profiles in SHR suggest an increased number of cells in the media. No difference was found in maximum force per unit cell area between SHR (271 +/- 31, n = 7) and WKY (305 +/- 49 mN/mm2, n = 7). Cell orientation was almost circular in both groups, showing that force was measured in parallel to the cell long axis. Aortic segments were mounted in an apparatus for quick-release experiments. They were maximally stimulated and force steps were imposed at peak of contractions. The series elastic component, characterized by the initial elastic recoils at 0.75 lo, has similar stiffness values in SHR and WKY. Velocities were measured 100 msec after release. The results were fitted to Hill's equation and maximum shortening velocity (Vmax) computed. No difference in Vmax was found at 0.75 lo (WKY: 0.048 +/- 0.005; SHR: 0.042 +/- 0.006 lo/s, n = 6 for both). At 0.85 lo, the data were corrected for passive tension (40% to total). Vmax at 0.85 lo was 0.071 +/- 0.009 lo/s (n = 5) for WKY, and 0.069 +/- 0.007 lo/s (n = 5) for SHR. Similar Vmax and force per cell cross-sectional area suggest similar characteristics of actomyosin interaction in SHR and WKY aorta.

The physical and chemical changes in casein during the gelation owing to the chemical modification by dialdehyde starch (DAS) in 8–10% solution were studied using electron-microscopy, measuring the mechanical properties (shear deformation), turbidimetric titration, and determination of amino groups. The gelation which proceeds during a storage time of 2 weeks is accomplished by the formation of a super-molecular network structure. Depending on the conditions of modification (pH, percentage of DAS, protein concentration) a more or less dense network is formed. An increase of pH (in the range of pH 6,3–9,7) leads to an increase of gelation speed, which favours the formation of irregular network structures. The denser the network formed the smaller is the shear deformation measured by the device of Tolstoi. During the storage of the gels the plastic component of compliance decreases to a greater amount than the elastic one. Therefore the relative amount of elastic component increases. During the reaction with DAS the maximum of turbidity of the protein (solubility minimum) shifted to lower pH owing to a blockage of positively charged groups. On the contrary to the changes measured by physical methods, this shift is complete soon after a 1 day storage. Similarly the blockage of amino groups is finished in the most cases this time too.

The viscoelasticity of blood is quantified by studying the oscillatory flow of suspensions of RBC in plasma in 218 μm and 400 μm glass capillary tubes. The flow conditions are chosen to reflect normal physiological flow in small arterial vessels. Data are obtained for suspension hematocrits between 35 and 80 percent, and at physiological temperature (37°C) The results indicate that the elastic component of the viscoelasticity of blood is effectively negligible for the conditions of this study; the measured pressure gradient-flowrate relationship is dominated by the viscous component of blood viscoelasticity.

Experiments were performed to indentify the series elastic component (SEC) in intact dog carotid artery held at in situ length. The vessels were studied during excitation of the muscle with norepinephrine and after metabolic poisoning with potassium cyanide and sodium iodoacetate. Static circumferential stress-strain curves and stress-quick-release stiffness curves were examined to evaluate Maxwell and Voigt model elements. The vessels were studied at 33, 36, and 39 degrees C. Temperature variations altered active stress, but did not alter connective tissue properties or the Maxwell SEC stiffness. The Voigt model SEC stiffness was altered, but this was secondary to changes in active stress. Thus, most of the SEC is separate from the contractile apparatus. Other vessels were treated with elastase, collagenase, or hyaluronidase to digest the connective tissue components of the wall. Hyaluronidase had no effect on mechanics. Elastase and collagenase altered connective tissue properties, but only elastase unequivocally altered SEC stiffness. This analysis indicated 1) that the carotid artery wall is better represented by a Maxwell model than a Voigt model, and 2) that the SEC in intact carotid artery is primarily elastin.

1. Tension responses of relaxed human lower leg muscles were recorded during applied triangular stretch cycles at a range of constant angular velocities which were below the threshold for inducing stretch reflexes. 2. Length-tension curves so obtained begin with a steep initial rising phase which is demonstrated to be equivalent to the 'short-range elastic component' (s.r.e.c.) observed in resting frog muscle (Hill, 1968). The s.r.e.c. develops only gradually following a stretch-release cycle. The time course can be described by a saturation function. It is suggested that this can be explained as resulting from a slow shift of the kinetic equilibrium between attached and detached cross-bridges towards attached cross-bridges. A kinetic model is presented, by which the sum of the cross-bridge formation and decay rate constants can be calculated from the saturation curves. 3. The recovery of resting tension following a stretch-release cycle proceeds at a significantly higher rate than the development of the s.r.e.c. Resting tension is also selectively influenced by passive movements of very small amplitude. This further suggests that the s.r.e.c. and resting tension are generated by different sources.

The magnetic properties of amorphous (Fe x Ni 100−x ) 75 P 16 B 6 Al 3 have been investigated in the critical concentration region ( x c ≈ 17) via neutron scattering. For x > x c a transition to ferromagnetism is first observed followed at lower temperatures by an evolution to spin-glass behavior. Associated with this low temperature state are two distinct time scales corresponding to a resolution-limited elastic peak and to excitations. The temperature dependence of the elastic component is directly related to the spin-glass order parameter and indicates that there is a region of temperature where ferromagnetism and spin-glass order coexist.

Alteration in the rheological behavior of milk during acidification were studied. Structure formation during gelling was monitored by a small strain rheological scanner. Dynamic viscoelastic properties were monitored as a function of time and temperature. Time of onset of gelation, rate of network formation and development of the elastic component during acidification were accelerated at higher temperatures (55°C). Addition of calcium (0–40 mM) facilitated gelation. Preheating milk at 90°C for 5 min prior to acidification enhanced gelation and induced protein-protein network formation. The number or strength of elastically effective bonds between protein molecules were reduced and gels of lower firmness were obtained with preheated milk, compared to gels made from unhealed milk.

1. The force-extension curve of the series elastic elements of the frog gastrocnemius has been determined up to the force attained during stretching by means of the isotonic quick-release method, modified in order to allow the release of the muscle immediately after stretching.2. The series compliance decreases progressively up to a stress value of about 2 kg/cm(2) and then it remains constant up to the maximal values of stress attained (about 10 kg/cm(2)).3. The lengthening of the series elastic elements when the stress rises to its full isometric value (P(0)l(0)/M = 5.2 kg/cm(2)) is about 3% of the muscle resting length, l(0). The Young's modulus in the linear part of the diagram is 294 kg/cm(2).4. The elastic energy stored up to P(0) is on average 55 g cm/g; an additional amount of 63 g cm/g is stored during stretching the contracted muscle.

In muscular contraction the development of tension requires that the contractile component should shorten and stretch the series elastic component. In an isometric twitch the maximum tension is reached as a balance between two opposing processes, internal shortening on the one hand and decay of the active state (relaxation) on the other. The fact that the maximum tension in a twitch is considerably less than in a tetanus has been attributed to oncoming relaxation allowing insufficient time for internal shortening to be completed. The maximum tension in a twitch is considerably reduced by a rise of temperature, while that in a tetanus is somewhat increased. This would require that the temperature coefficient of the velocity of shortening should be substantially less than that of the decay of activity. Evidence for this exists. On this view the effect of a quick stretch, applied during the early stage of a twitch, in increasing the tension ratio, stretch/isometric, should be much greater at a higher temperature. This expectation is confirmed on frogs’ muscles over the range 0 to 20°C. The effect of temperature, therefore, on the size of a twitch can be attributed to the difference between the temperature coefficients of velocity of shortening and rate of relaxation.

Product‐velocity‐vector distributions have been determined for the reactive and inelastic scattering of N2+ by H2, D2, and HD. These distributions show that the reaction proceeds by a direct short‐lived interaction rather than by a long‐lived collision complex. Most products are scattered in the original direction of the N2+ projectile at a speed somewhat greater than calculated from the ideal stripping model. The internal excitation of N2D+ and N2H+ is very high and decreases somewhat with increasing scattering angle. For HD there is an isotope effect that favors N2H+ by large factors at small scattering angles, and N2D+ by smaller factors at large angles. The N2+ scattered from D2 shows very little elastic component, but does reveal an inelastic process which is probably the collisional dissociation of D2.