Rupture Energies Research Articles

Effects of cryo-preservation on skeletal muscle tissues mechanical behavior under tensile and peeling tests until rupture

The most common method to study the mechanical behavior of soft tissue is to test animal specimens, which should be prepared as soon as possible after the death to avoid biological deterioration effects such as rigor mortis. Freezing and cryo-preservation could allow extending the time between procurement and implantation. From a mechanical perspective, tissue preservation could influence mechanical testing results.Therefore, this study focuses on the influence of cryo-preserved samples on their mechanical behavior, especially at the rupture.In order to analyze this aspect, two tests were performed on the porcine abdominal wall. A tensile test to study the elastic behavior of samples and the tensile strength until rupture. A peeling test to more finely investigate the cohesion between muscle fibers.No statistical difference could be observed following tensile test. However, peeling tests between cryo-preserved and control samples showed a clear statistical difference with a p-value of 0.0097 for Gp. Indeed, energy release rate was higher for the Cryo-preserve group than the Control group with Gp = 0.36 ± 0.07 N/mm vs 0.26 ± 0.10 N/mm. This difference suggests that the characterization of rupture energies for muscular tissue should be done without having frozen the samples, even with a cryopreservative agent.These results could also indicate that even if the rupture mode is the same between mechanical tests, a different rupture direction could imply different mechanical preservations for soft tissues.This study could help to understand the difficult mechanical preservation of soft tissues, especially on the rupture behavior. Future studies on skeletal muscles will be necessary to compare our results, especially in peeling.

Reactivity of O-Drug Bond in some Suggested Voltarine Carriers: Semiempirical and ab Initio Methods

In this work, the possibility to use new suggested carriers (D= Aspirin, Ibuprofen, Paracetamol, Tramal) is discussed for diclofenac drug (voltarine) by using quantum mechanics calculations. The calculation methods (PM3) and (DFT) have been used for determination the reaction path of (O-D) bond rupture energies. Different groups of drugs as a carrier for diclofenac prodrugs (in a vacuum) have been used; at their optimized geometries. The calculations included the geometrical structure and some of the physical properties, in addition to the toxicity, biological activity, and NLO properties of the prodrugs, investigated using HF method. The calculations were done by Gaussian 09 program. The comparison was made for total energies of reactants, activation energies, and transition states to final products. The suggested prodrugs aim to improve the diclofenac carrier's properties and obtain new alternatives for the approved carriers theoretically.

Global insight into microwave stoneware firing: Macro and microstructural changes

AbstractIndustrial competition and environmental concerns lead to the exploration of alternative and energy‐efficient technologies for ceramic materials processing. The main objective of this work was to present microwave heating as a viable option for stoneware processing. Stoneware functional properties are presented and discussed, with emphasis on impact strength, water absorption, porosity, and color. Microstructure analyses show that microwave‐ and gas‐fired samples have higher densifications than electrically fired samples. A relevant finding for processing conditions is that microwave firing requires temperatures approximately 100°C lower than those required by conventional firing. Microwave‐fired samples’ rupture energies are approximately twice (0.57 ± 0.06 (J)) those of the reference samples (0.26 ± 0.03 (J)), and their water absorptions are approximately one‐half (1.5% at 1170°C and 0.8% at 1190°C) of those of the reference samples (2.0%), whereas the water absorption of electrically fired samples at 1180°C has been estimated to be 7.5%. Color analysis also evidences a shift to lower microwave firing temperatures, what is attributed to the enhanced transformations promoted by microwave heating when comparing with the transformations promoted by conventional (gas or electric) heating.

Theoretical Study to Predict the Ability to Use Different Organic Substituents as Carrier Linkages for Diclofenac

The research includes unrestricted (UDFT) and (UPM3) quantum mechanical calculations for studying the reaction path of bonds rupture energies of (O-R) and (C-OAr) in twelve diclofenac derivatives containing different substituted organic groups. All the calculations were performed at the optimize geometries in vacuum phase by using Gaussian 09 program. Comparison was done between the studied diclofenac derivatives and the standard ionic diclofenac of sodium and potassium included geometrical structures, physical properties, total energies of the reactants and products, activation energies and transition states. The results showed that some substituted organic groups could be used to form good carrier bonds for the acidic drug diclofenac, while others were less efficient depending on the nature of the substituted carrier, and that there is a preference for carriers of the type (–R) over the carriers of the type (–Ar).

Prediction the ability of using vitamins and amino acids as carrier’s linkage for diclofenac drug: A theoretical and comparative approach

In this research, the possibility of using new suggested carriers (A) of vitamins (D3 and C) and amino acids (Leucine and Threonine) for diclofenac (Dc) drugs was addressed. Parameterization model 3 (PM3), unrestricted Harttre-Fock (UHF), unrestricted Density Functional Theory (U-DFT), and Docking have been used to calculate the reaction path of (O-A) bond rupture energies in diclofenac prodrugs (in vacuum). All were done at their optimize geometries by using Gaussian 09, Molecular Graphic Laboratory M.G.L. tools, Vina, BIOVIA (D.S.V.) and PyMol programs. The calculation involved the geometric structures, physical properties, lethal concentration (LC50), biological activity, and N.L.O. properties. Furthermore, the binding between Ribosomal protein S9 structure and the prodrugs in the liver were studied. Comparisons were made for the energies of the reactants, transition states, and products. The new carriers aim to improve the diclofenac drug's properties and provide new alternatives for the approved carriers. By examining the path of reaction of O-breakage energies, D3 and Threonine (Thr) represent a good prodrug due to their low heat of cracking (ΔHc), energy gap (ΔE), and activation energy (Ea#). At the same time, vitamin C and Leucine (Lue) showed a lower influence. In addition, LC50 showed theoretically that the maximum concentration of diclofenac carriers (Dc. A) was 9.290 × 10−10, 3.390 × 10−7, 6.762 × 10−7, and 1.125 × 10−6 M for Dc.D3, Dc.C, Dc.Leu, and Dc.Thr can be used, respectively. The order of the biological activity for the investigated carriers was Dc.D3 > Dc.C > Dc.Leu > Dc.Thr. The order of N.L.O. activity was Dc.D3 > Dc.Leu > Dc.C > Dc.Thr. In addition, the Autodock studies showed the ability of the suggested prodrugs to link with Ribosomal protein S9 structure in the liver for metabolism and producing an active drug (diclofenac acid). The suggested carriers were better than the common carriers (Na+ and K+) according to the binding energy.

Strain rate dependent mechanical behavior of B. mori silk, A. assama silk, A. pernyi silk and A. ventricosus spider silk

In this study, the effect of strain rate on the mechanical behavior of B. mori silk, A. assama silk, A. pernyi silk and A. ventricosus spider silk were systematically investigated. Dynamic tensile tests were conducted for these natural silk fibers to obtain their mechanical properties under five strain rates. Tensile test results indicated that the stiffness, tensile strength, failure strain and rupture energy of A. ventricosus spider silk all increase with increasing strain rates. A. ventricosus spider silk was found to have the highest average Weibull modulus among these silk fibers, showing its excellent reliability. Then, based on Zener model and Weibull statistics, this study theoretically characterized and analyzed the influence of strain rate on their mechanical properties including stress-strain responses, tensile strengths, Weibull parameters, failure strains and rupture energies. Some insights that can be helpful for better understanding their strain rate dependent mechanical behavior were provided.

Effects of shape feature on compression characteristics and crack rules of maize kernel

The physical and compression properties were analyzed for three kernel shapes of hybrid maize, Dika 517 and Denghai 618, grown under the same agroecological conditions. The average forces required to rupture the kernels of Dika 517 and Denghai 618 were 150.35 ± 80.90 N and 161.74 ± 86.16 N, respectively, and the average kernel rupture energies were 134.25 ± 50.77 mJ and 137.78 ± 58.35 mJ, respectively. Pyramidal and rectangular shape kernels exhibited the largest rupture force and energy at the thickness position, and round kernels have the highest rupture force and energy at length. The energy absorbed by kernels increased with an increased loading rate. The law of cracking for various surfaces differed under different loading directions for different shape kernels. Practical applications The physical and mechanical properties of maize kernels are different because of their different shapes. Understanding the physical and mechanical properties of maize kernels is important to assess the product quality, but is also crucial for the effective design and development of equipment and structures for efficient sowing, harvesting, transporting, handling, and processing.

Measurement of Engineering Properties Necessary to the Design of Drumstick (Moringa oleifera L.) Pod Sheller

, 2015Purpose: Designing equipment for processing, sorting, and other post-harvest operations of agricultural products requires information about their physical properties. This study was conducted to investigate some of the mechanical and physical properties of Moringa oleifera L . pods and seeds. Methods: Properties such as the length, width, thickness, bulk density, porosity, mass, static coefficient of friction, and angle of repose were determined as a function of moisture content. Statistical data and force-deformation curves obtained at each loading orientation and moisture level were analyzed for bioyield point, bioyield strength, yield force, rupture point, and rupture strength using a testrometric machine. Result: The basic dimensions (length, width, and thickness) of moringa pods and seeds were found to increase linearly from 311.15 to 371.45 mm, 22.79 to 31.22 mm, and 22.24 to 29.88 mm, respectively, in the moisture range of 12 to 49.5% d.b. The coefficient of friction for both pods and seeds increased linearly with an increase in moisture content on all the surfaces used. The highest value was recorded on mild steel, with 0.581 for pods and 0.3533 for seeds, and the lowest on glass for pods, with a value of 0.501, and of 0.2933 for seeds on galvanized steel. The bioyield and rupture forces, bioyield and rupture energies, and deformation of the pods decreased with an increase in moisture content to a minimum value, then increased with further decrease within the moisture content range, while the yield force increased to a maximum value and then decreased as the moisture content increased. Conclusion: These results will help to determine the most suitable conditions for processing, transporting, and storing moringa pods, and to provide relevant data useful in designing handling and processing equipment for the crop.Keywords: Angle of Repose, Deformation, Drumstick pod sheller, Moisture content, Moringa oleifera

New insights on the interface between metal oxide and biosystem.

The interface between titanium dioxide and biological solution is relevant for the bioactivity of titanium implants. Adhesion phenomena between inorganic solids are of general interest for mineralization and bone formation processes. Such interfaces are complex systems with many constituents including the hydroxylated metal oxide support, hydrocarbon contamination, ionic water solution and a variety of biopolymers. Our computational methods comprise classical molecular dynamics with around 106 atoms in the 10-100 ns range and ab initio molecular dynamics wit 100-200 atoms for some ps. • Electronic structure calculations show that even very thin layers of TiO2 on Ti metal may be commensurate and crystalline [1]. A variety of smooth and rough surfaces are implemented in force field simulations. • The oxide is hydroxylated and its surface charge density correlates with the pH-value. The highly hydrophilic TiO2 is in practice screened by hydrocarbons, which may enhance inflammatory complications of implants [2]. Simulations on the nature of this contamination are presented. • Sequence specific protein adsorption on inorganic surfaces was found in several experiments on inorganic surfaces, even though no key-lock mechanism is conceivable. We propose two effects [3]: (i) Contacts of single amino acid side chains to local charges in the surface have rupture energies, which sensitively depend on the electrostatics. The adhesion of appropriate double contacts is very strong exceeding simple hydrogen bonding. (ii) Soft motifs of proteins easier attach to the surface than rigid helices or strands. • Close to solids water has an ordered structure, which only slightly depends on the surface charge density. These layers hinder protein adsorption. A major difference to the bulk is the reduced water mobility there.

Structural Implications of Hydrogen-Bond Energetics in Membrane Proteins Revealed by High-Pressure Spectroscopy

The light-harvesting 1 (LH1) integral membrane complex of Rhodobacter sphaeroides provides a convenient model system in which to examine the poorly understood role of hydrogen bonds (H-bonds) as stabilizing factors in membrane protein complexes. We used noncovalently bound arrays of bacteriochlorophyll chromophores within native and genetically modified variants of LH1 complexes to monitor local changes in the chromophore binding sites induced by externally applied hydrostatic pressure. Whereas membrane-bound complexes demonstrated very high resilience to pressures reaching 2.1 GPa, characteristic discontinuous shifts and broadenings of the absorption spectra were observed around 1 GPa for detergent-solubilized proteins, in similarity to those observed when specific (α or β) H-bonds between the chromophores and the surrounding protein were selectively removed by mutagenesis. These pressure effects, which were reversible upon decompression, allowed us to estimate the rupture energies of H-bonds to the chromophores in LH1 complexes. A quasi-independent, additive role of H-bonds in the α- and β-sublattices in reinforcing the wild-type LH1 complex was established. A comparison of a reaction-center-deficient LH1 complex with complexes containing reaction centers also demonstrated a stabilizing effect of the reaction center. This study thus provides important insights into the design principles of natural photosynthetic complexes.

On the prediction of long‐term creep‐failure of GRP pipes in aqueous environment

AbstractThe aim of this work was to study the long‐term failure of GRP (Glass fiber‐reinforced Polymer) pipes under the influence of moisture absorption. These pipes are used in water transportation, which has an important effect on the mechanical properties of the polymeric matrix. The GRP pipes are usually tested under ring deflection or internal pressure conditions. This study presents and analyzes experimental creep‐rupture data obtained from standard test methods under ring deflection conditions. This loading configuration simulates in laboratory the conditions verified in a subsoil installation. The creep testing was carried out under constant dead weight on unconditioned and preconditioned samples in a submerged condition. The diametrical deflection of samples was measured periodically, and the time to failure of each sample was recorded. The main purpose of this work was to determine the short and long‐term rupture energies of GRP pipes and assess the influence of moisture preconditioning on those values. The observed failure mode was always the same. It was concluded that the energy at failure decreases with time. The influence of the preconditioning on the creep‐rupture of GRP pipes was considered negligible. Different time‐dependent failure models were described and used for long‐term extrapolation of the experimental data. The maximum strain at failure decreased about 12% from 0.1 to 1,000 hr of creep testing. Furthermore, data extrapolation to 50 years predicts a reduction of strength of about 60%, founded on the most conservative time‐dependent failure criterion. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers

Two-Center, Three-Center, and Four-Center Dative π-Bonding Systems in Boron−Nitrogen Compounds Studied by Density Functional Theory Calculations: The Molecular Structures of Bis(dimethylboryl)amine, Bis(dimethylboryl)methylamine and Bis(dimethylamino)methylborane Determined by Gas Electron Diffraction

The nature of the two-center, two-electron (2c,2e) dative π-bonding system in aminoboranes has been explored by optimizing the equilibrium structures of R2NBR‘2 (R, R‘ = H or Me) by DFT calculations at the B3PW91/6-311++G** level. The π-bond rupture energies were determined by optimizing models in which the relative orientation of the R2N and BR‘2 fragments was fixed in such a manner that the lone-pair atomic orbital on N was orthogonal to the vacant 2p-orbital on the B atom. Similar calculations were carried out on the (3c,2e) dative π-bonding systems of bisborylamines, RN(BR‘2)2; the (3c,4e) π-system of bisaminoboranes, RB(NR‘2)2; the trigonal (4c,2e) π-bonding systems of trisborylamines, N(BR2)3, and the (4c,6e) π-systems of trisaminoboranes, B(NR2)3. The structures of HN(BMe2)2, MeN(BMe2)2, and MeB(NMe2)2 determined by gas electron diffraction were in good agreement with those determined by calculations. The mean N−B π-bond rupture energies, 〈Dπ〉, in the prototypical compounds H2NBH2, HN(BH2)2, HB(NH2)2, N(BH2)3, and B(NH2)3 were found to depend not on the number of π-electrons, but on the number of centers. The mean π-bond rupture energies of the prototypical 2c, 3c, and 4c compounds were found to vary in the order 4.0:3.0:2.0. When H atoms at an acceptor atom (B) are replaced by more electron releasing methyl groups, 〈Dπ〉 is significantly reduced due to a synergetic combination of destabilizing inductive effects and steric strain. When H atoms at the donor atom (N) are replaced by Me groups, the effect on 〈Dπ〉 is determined by the balance of stabilizing inductive and destabilizing steric effects. The N−B bond distances in the 14 molecules tend to decrease with increasing mean π-bond rupture energy. Linear correlation analysis yields R(N−B) = 149.3 pm − (0.075 pm mol kJ-1) 〈Dπ〉 and a correlation coefficient of ρ = 0.97.

Novel Modulation of Drug Delivery Using Binary Zinc-Alginate-Pectinate Polyspheres for Zero-Order Kinetics Over Several Days: Experimental Design Strategy to Elucidate the Crosslinking Mechanism

A Box-Behnken design was applied to mathematically establish whether different degrees of crosslinking were induced by Zn2 + and Ca2 + ions in polyspheres composed of alginate and/or pectin, and the model drug ibuprofen. Based on their different crystal structures and coordination numbers, a theoretical model was proposed demonstrating that Zn2 + ions preferentially crosslink alginate and pectin. In addition, the lower coordination number of Zn2 + (4–6) would significantly retard hydration of both polymers, as opposed to Ca2 + (7–9). The responses studied for 28 statistically derived polyspheres included drug encapsulation efficiency, physicomechanical behavior, and in vitro drug release potential. Single-tailed Student's t-tests on data generated for the encapsulation efficiencies, primary facture values, and rupture energies indicated that Zn2 + was statistically superior (p < 0.05) in crosslinking alginate and pectin. Further textural analysis revealed a good correlation between the Brinell hardness number and fracture load, while an inverse relationship was found for matrix tensile strength. Viscosity studies demonstrated different in situ crosslinking thresholds for Zn2 +. The Durbin-Watson statistic and correlation coefficient revealed that the quadratic regression function was highly accurate in predicting the responses. Using a generalized reduced gradient algorithm on dissolution values obtained after 2 hours (t2h) provided optimized solutions for achieving zero-order release extending from 2 hours to 7 days. Mathematical simulations projected drug release from 25 to 50 days.

Diels—Alder Reaction. Effect of Internal and External Factors on the Reactivity of Diene—Dienophile Systems

AbstractFor Abstract see ChemInform Abstract in Full Text.

Rupture energy and wetting behavior of pendular liquid bridges in relation to the spherical agglomeration process

A novel micro force balance (MFB) is used to investigate the rupture energy of a silicon oil liquid bridge formed in water between two glass particles of either the same or dissimilar surface energy. Rupture energies are integrated from force curves and compared with the models proposed by Simons et al. (Chem. Eng. Sci. 49 (1994) 2331) and Pitois et al. (Eur. Phys. J. B 23 (2001) 79). The latter showed slightly better agreement to the experimental data. Glass ballotini (∼100 μm diameter) are either silanized, in order to increase their wettability toward the oil binder, or kept untreated. Results showed how the interaction between the binder and the particle influences the geometry, the capillary pressure, the force, and the rupture energy of the liquid bridge. Higher values of force and liquid bridge energy were measured between particles characterized by higher interaction ( silanized–silanized configuration). A thermodynamic approach to the evaluation of the energy stored in a liquid bridge is also proposed. The mechanical work done to stretch apart the liquid bridge is evaluated as the difference of internal and hysteresis energy between the initial and the rupture configuration of the bridge. This approach showed good agreement with the experimental data only for liquid bridges formed between silanized and untreated glass particles.

Diels—Alder reaction. Effect of internal and external factors on the reactivity of diene—dienophile systems

The key factors influencing the Diels—Alder reaction rate at ambient and elevated pressures were elucidated using data on the reactivity of various diene—dienophile systems in usual and Lewis acid-catalyzed Diels—Alder reactions, the reaction enthalpy, complex formation, dissolution, and solvation, and the donor-acceptor properties of the reactants. It was found that taking account of both the orbital interaction energy and the balance of bond rupture and formation energies allows correct prediction of the reaction rate in the absence or in the presence of Lewis acids.

Tensile bond strength development between liquid-bound pellets during compression

Novel experiments have been performed to measure the tensile bond strength developed between two liquid-bound pellets when they are compressed together at low strain rates. Pellets 20 mm in diameter were made from 75-μm mass-mean sized glass ballotini with water and three different viscosity silicone oils (0.01, 1 and 60 Pa s). The water-bound pellets formed bonds which were brittle and ruptured quickly when strained in tension. The silicone oil-bound pellets were plastic and stretched back a significant fraction of their original length before the bond ruptured. The peak tensile strengths and rupture energies of the bonds were proportional to the radial strain in the bond zone. A model was developed based on a cold-welding analogy to predict the peak tensile strength of the bond as a function of the strength of the bulk pellets and the extent of radial strain in the bond region. There was good agreement between the model predictions and the experimental results for radial strains less than 7%. At higher radial strains, the bond strength appeared to level off, probably because the bonds began to fail by gradually peeling apart rather than by simultaneous rupture across the whole failure plane. This simple model should help in predicting the bond strength formed when two liquid-bound agglomerates collide, which will be important in understanding and modelling granule coalescence growth behaviour. It was also observed that the compressive strength of the pellets decreased with increasing liquid viscosity, probably due to a lubrication effect reducing inter-particle friction. This contrasts with the effect of liquid viscosity seen by other workers at high strain rates, and suggests that the strength ranking of formulations with viscous binders may be strain-rate dependent.

Electronic Structure of the 3d Metal Monoxide Anions

The electronic and geometrical structure of the ground and excited states of the 3d metal monoxide anions ScO-, TiO-, VO-, CrO-, MnO-, FeO-, CoO-, NiO-, CuO-, and ZnO- were calculated using density functional theory and different formulations of generalized-gradient approximations for the exchange-correlation potential. It was found that the anion states with low- and high-spin multiplicities with respect to the ground-state spin multiplicities of the corresponding neutral parents are stable toward autodetachment of the extra electron. All the low-spin multiplicity anion states are more stable than the high-spin ones, except for that of CrO-, whose ground state appears to be a high-spin multiplicity state. Computed electron affinities of the neutral monoxides are in good agreement with the experimental values obtained by laser photoelectron spectroscopy. It is shown that pure density functional methods are generally superior to a hybrid Hartree−Fock density-functional-theory approach, except for reproducing bond rupture energies.

Estimation of Weibull Brittle Fracture Parameters for Heterogeneous Materials

AbstractBrittle fracture of heterogeneous materials such as dry soil aggregates is not well understood. The flaws in such materials occur as voids across a wide range of length scales. As a result, failure is an inherently variable phenomenon that is best analyzed using weakestlink (Weibull) theory combined with fractal geometry. According to this probabilistic approach, samples to be fractured are assumed to be exactly the same size. However, sample size variation can result in biased estimates of the model parameters, log(α), β, and D. Our objective was to derive and test an equation for eliminating this bias by adjusting survival probabilities to a common value of sample length. Rupture energies were determined on 1920 air‐dry soil peds collected from three long‐term tillage treatments on a Maury silt loam (fine, mixed, mesic Typic Paleudalf). Following adjustment for sample size variation, characteristic strength, as parameterized by log(α), typically decreased with increasing ped size. Unbiased estimates of β indicated a wider spread of strengths than reported previously. Unbiased estimates of D, the fractal scaling parameter, were lower than those obtained using other methods, possibly because of renormalization with respect to the distribution of fragile elements instead of voids. Tillage treatment significantly influenced all three parameters, with the strength of no‐till peds decreasing more rapidly with increasing size than conventional‐till peds. Analysis of the relative errors associated with parameter estimates computed using the adjusted survival probabilities indicated that at least 20 samples per sieved fraction should be used as a standard in future brittle fracture studies on heterogeneous materials.

Modelling of Binder-Induced Agglomeration

From the analysis of pendular liquid bridge forces between spherical particles, a model has been developed to predict bridge rupture energies. Whilst this model has been shown to predict the correct trends in certain stages of agglomeration, it is limited by the assumptions of zero contact angle, toroidal bridge geometry, spherical particles and quasi-static rupture. The work described here is aimed at extending the model to more generally applicable conditions using direct measurement of bridge rupture energies between particles down to 3 mu m in diameter under different physiochemical conditions. Initial results show that the spreading coefficient of the binder to the particle has a marked effect on the dynamic behaviour of the bridge itself and its subsequent geometry at equilibrium.