Cohesive Bonds Research Articles

Kissing Christians: Ritual and Community in the Late Ancient Church (review)

Christians: Ritual and Community in the Late Ancient Church. By Michael Philip Penn. [Divinations: Rereading Late Ancient Religion.] (Philadelphia: University of Pennsylvania Press. 2005. Pp. viiii, 186. $42.50.) Michael Penn begins his study of the kiss in early Christianity with a quotation from Clement: There are those who do nothing but make the church resound with the kiss, while not having love them. This, the unrestrained use of the kiss, also causes shameful suspicions and slander.... Hidden among discussions of fashion, gambling, and the racetrack, this prohibition against unrestrained and passionate kissing in the church gave the author-as I suspect most others who have read Clement-quite a shock! But unlike most of us, Penn followed his instincts and stopped, and listened, and saw anew the importance of ritual, especially the physical act of kissing in early Christian worship.This discovery led Penn to re-evaluate, as he confesses, his image of the ancient Church. result is an insightful study of ritual, power dynamics, community formation, and the setting of boundaries that identify the community first to itself and then to those outside.Though not the first study to explore the role and value of the kiss in Christian worship (the work of L. Edward Phillips, Nicolas J. Perella, and others informs much of the historical and liturgical background), Penn brings a fresh and truly interdisciplinary approach to his study on and its meaning. Interacting with the works of Mary Douglas on purity and boundary formation, Catherine Bell on formation, and Pierre Bourdieu on distinction, among others, Penn shows how the kiss functioned as a performative identifier of difference and community demarcations for the initiated and, at the same time, those outside the community. Having consulted over a thousand ancient references to kissing (p. 6), Penn in his first chapter, titled teasingly, Kissing Basics, examines how this and expected public (and of course also private) gesture of kissing family members, friends, lovers, and so forth was distinguished, transformed, and ritualized into a socially productive gesture within the kiss's larger cultural (p. 17). In the growing context of the Christian community, new definitions of common and ritual were now necessary. In The Kiss That Binds: Christian Communities and Group Cohesion, (chap. 2) Penn tells us how kissing emphasized the bonds of the new community, as both Christian and non-Christian authors viewed kissing as a way to promote group (p. 28). To make the point, Penn traces these bonds of social and group cohesion and difference its Greco-Roman milieu and structures of social stratification, and then moves to a discussion of kissing as a spiritual exchange to show how Christian communities transformed the popular understanding of the physical exchange of souls (or spirit) through the act of kissing and employed this pneumatological model. …

Charge Regulation as a Stabilization Mechanism for Shell-Like Assemblies of Polyoxometalates

We show that the equilibrium size of single-layer shells composed of polyoxometalate macroions is inversely proportional to the dielectric constant of the medium in which they are dispersed. This behavior is consistent with a stabilization mechanism based on Coulomb repulsion combined with charge regulation. We estimate the cohesive energy per bond between macroions on the shells to be approximately -6kT. This number is extracted from analysis based on a charge regulation model in combination with a model for defects on a sphere. The value of the cohesive bond energy is in agreement with the model-independent critical aggregate concentration. This observation points to a new class of thermodynamically stable shell-like objects. We point out the possible relevance our findings have for certain surfactant systems.

Fracture of rigid solids: a discrete approach based on damaging interface modelling

We describe the progressive and delayed fracture of rigid solids by a discrete modelling. Each rigid solid is considered as an assembly of particles with initial cohesive bonds, the latter decreasing progressively during the loading. A damaging interface model is proposed to describe this progressive phenomenon. The model has been implemented in a discrete element code. The first illustrative example, which is actually a parametric study, deals with the progressive damage and sudden fracture of a single interface submitted to an uniaxial tension. The second example is related to the crushing of an assembly of rigid solids—i.e. a granular medium—submitted to an oedometric compression. To cite this article: C. Silvani et al., C. R. Mecanique 335 (2007).

An investigation of Roman mortar technology through the petrographic analysis of archaeological material

This paper studies Roman mortars to demonstrate that petrographic analysis provides valuable information on ancient mortar technology. Facts on lime technology relating calcination and slaking were obtained through petrographic analysis. The analysis also revealed the composition and origin of raw materials, pozzolanic additions and mortar hydraulicity. The results were contrasted with ancient Roman technology records including Cato, Pliny, Vitruvius, Palladius and Faventinus. The binders’ petrofabric suggests a high reactivity and water retention capacity and a low shrinkage for the lime. These agree with the long slaking and soft burning advised by the Romans. The strong binder cohesion and perfect aggregate-binder bond of most mortars together with the presence of aggregate-binder reaction denotes a high reactivity for the lime which also agrees with soft burning. The mortars were probably made with a non-hydraulic or feebly-hydraulic lime and their hydraulicity is mainly due to the addition of pozzolans (ceramics). These agree with Roman authors consistently advising to use a pure carbonate rock for lime making. The pozzolanic additions are probably responsible for the good durability of the mortars.

Use of mechanics of cohesive granular media for analysis of hardness and vitreousness of wheat endosperm

The characterisation of the wheat endosperm by mechanical tests of compression highlighted a relation between the rupture energy and the elasticity modulus for different varieties of wheat; this relation allows us to distinguish mealy and vitreous endosperms. An approach based on the micromechanics of cohesive granular materials is used to analyse these experimental results. A geometrical model of the wheat endosperm made of grains linked by cohesive bonds is proposed. We introduced two parameters, the first one α represents the percentage of active bonds (bonds where the stiffness and strength are non-zero), and the second one β represents the threshold of the bond's rupture. The parameter β can be related to the cross-section of the bond. This model successfully describes the mechanical tests on the wheat endosperm. The comparison with the experimental tests makes it possible to clearly differentiate vitreous wheats and mealy wheats and then attribute this property to the parameter β. The model shows the same tendency as regards the evolution of the rupture energy and the elastic modulus with the parameter α. The modelling of endosperm by the mechanics of cohesive granular media provides a new theoretical framework to interpret the rheology of endosperm. This approach allows us to connect this rheology to the mechanical actions at the scale of the granules.

Bonding properties of newly erupted and mature premolars

The purpose of this study was to determine whether there were differences in bond strength between mature and newly erupted teeth when using both conventional and self-etching primer techniques for bonding orthodontic appliances. The nature of adhesive bond failure among the groups was also compared by using the adhesive remnant index (ARI). Premolars were collected, randomly divided, and bonded with either the conventional or the self-etching technique. Brackets were debonded on a testing machine with a shear-testing device. Bond strengths were compared with ANOVA and the Weibull analysis. There were no statistically significant differences in bond strength values between the conventional etching and the self-etching primer groups or between newly erupted and mature teeth. ARI scores differed between mature and newly erupted teeth. Newly erupted teeth had more adhesive failures, and mature teeth had more cohesive bond failures at the enamel-composite resin interface. Based on these results, bond strength does not appear to be affected by the posteruptive enamel maturation process.

Hemispherical bubbles growth on electrochemically charged aluminum with hydrogen

The formation of surface bubbles (blisters) in aluminum during electrochemical charging by hydrogen was studied. The experiments reveal that, in aluminum samples, a wide distribution of hydrogen bubbles on the surface (blisters) was produced during electrochemical charging. A wide variety in density, distribution and geometrical shape of the surface bubbles was obtained, with sizes ranging from large (tens of micrometers in the diameter) to very small (nanometers in the diameter). Bubble growth in various shapes is controlled by hydrogen diffusion to the surface layer of the aluminum, from the defects region below it together with separation of cohesive atomic bonds between the hydroxide layer and the aluminum matrix. In such electrochemically charged aluminum the various hydrogen bubble structures formed during the growth process in the hydroxide layer, can be developed mathematically by the principles used in obtaining the shapes of the grains-boundaries in the polycrystalline microstructures of material.

Effect of Modification Processes on Bond Energy of Asphalt Binders

Performance of asphalt pavements depends on the properties of its constituent materials, mixture volumetrics, and external factors such as load and environment. An important material property that influences the performance of an asphalt mixture is the surface free energy of the asphalt binder and the aggregate. Surface free energy governs the adhesive bond strength between the asphalt binder and the aggregate as well as the cohesive bond strength of the asphalt binder. These bond energies in turn influence the resistance of the asphalt mixture to distresses such as fatigue cracking and moisture induced damage. Asphalt binders undergo several types of engineering and natural modifications that influence their chemical and mechanical properties. Three common examples of modifications are the addition of polymers, addition of additives (e.g., antistrip agents), and oxidative aging of the asphalt binder. This paper is part of a study conducted to examine the effect of different types of modifications on the surface free energy components of the asphalt binder. The change in surface free energy was used to calculate parameters that are related to the performance of the asphalt mixtures. Results from this study demonstrate that the magnitude and nature of change to the surface free energy and concomitant performance-related parameters varied significantly among different asphalt binders. For example, certain modifications improved the performance of some binders while adversely affecting the performance of others. The experiment and analysis methods presented in this study can be used to examine the influence of modifications on performance and optimize the engineering properties of binders and asphalt mixtures.

Positive Emotions Preferentially Engage an Auditory–Motor “Mirror” System

Social interaction relies on the ability to react to communication signals. Although cortical sensory-motor "mirror" networks are thought to play a key role in visual aspects of primate communication, evidence for a similar generic role for auditory-motor interaction in primate nonverbal communication is lacking. We demonstrate that a network of human premotor cortical regions activated during facial movement is also involved in auditory processing of affective nonverbal vocalizations. Within this auditory-motor mirror network, distinct functional subsystems respond preferentially to emotional valence and arousal properties of heard vocalizations. Positive emotional valence enhanced activation in a left posterior inferior frontal region involved in representation of prototypic actions, whereas increasing arousal enhanced activation in presupplementary motor area cortex involved in higher-order motor control. Our findings demonstrate that listening to nonverbal vocalizations can automatically engage preparation of responsive orofacial gestures, an effect that is greatest for positive-valence and high-arousal emotions. The automatic engagement of responsive orofacial gestures by emotional vocalizations suggests that auditory-motor interactions provide a fundamental mechanism for mirroring the emotional states of others during primate social behavior. Motor facilitation by positive vocal emotions suggests a basic neural mechanism for establishing cohesive bonds within primate social groups.

Orientation-based Continuum Damage Models for Rocks

A general formulation of the Helmholtz free energy used in thermodynamics of damage process of rocks is derived within a multi-scale framework. Such a physically-based thermodynamic state potential has a hybrid, discrete/continuum, nature in the sense that it adopts a continuum description but subsumes the statistical ensemble average of the action of the entirety of microscopic degrees of freedom. The choice of the relevant damage variables results therefore directly from the breaking of contact cohesive bonds, and it naturally obeys the Clausius-Duhem inequality. Furthermore, motivated by the fact that the free energy is formulated by the integral of potentials independently defined on different orientations over the upper hemisphere, the damage evolution equation is formulated on a generic orientation. Consequently, the mechanical behavior of a rock material generally becomes anisotropic characteristics in the inelastic regime even if the material is initially isotropic, thus introducing dissipation-induced anisotropy in a very natural and simple way. Finally, the development of the lattice solid model can be cast into the framework of the orientation based continuum constitutive model.

The Sacred, Religion, and Morality

The Sacred, Religion, and Morality Romanus Cessario OP (bio) During the period that standard English-speaking authors refer to as that of modern continental philosophy, the trio of the "sacred," "religion," and "morality" became subjects of research in disciplines that developed out of or alongside classical theology and philosophy. The argument of the first half of this paper is that by and large this innovation has not been a fortuitous one for Catholic thought. For instance, it is generally agreed that August Comte (1798–1857) played a key role in the initial transformation of "religion" into what may be described as a Time-magazine sphere of society, that is, alongside the economy, politics, sports, theater, and so forth. His 1852 Catechism of Positivism supplied the founding charter for the discipline that has come to be known as the Sociology of Religion. This work, moreover, along with Comte's other writings influenced in a broad sense the development of modern sociology. Although born into a devout Catholic family, Isidore Auguste Marie François Xavier Comte's own views on religion reflect the intellectual uncertainties of his period. He subtitles his Catechism a "Summary Exposition of the Universal Religion, in Eleven Dialogues between a Woman and a Positivist Priest of Humanity."1 It [End Page 16] should be evident that August Comte does not escape the skepticism and confusion with respect to religion that infected certain French authors during the first half of the nineteenth century. Even Friedrich Nietzsche was moved to remark on the strained ambiguity that, in his caustic opinion, was characteristic of figures like Comte and Ernest Renan: "How strangely devout for our taste even these recent French sceptics are, to the extent they have some Celtic blood in their ancestry!"2 Émile Durkheim (1858–1917) played a crucial role in carrying Comte's views on religion to a next stage of reflection. Durkheim elucidated the nature of religion to be a celebration of a group's or a people's community or social solidarity.3 He postulated that common values form the cohesive bonds of society, particularly in primitive societies, although he also opined, as Mary Ann Glendon has observed, that in his own day communal religions had already lost most of their authority and effectiveness.4 Durkheim himself probably possessed a genuinely religious streak; his father had been the Chief Rabbi of the Vosges and Haute-Marne. Durkheim's own views on religion, however, are thoroughgoingly secular at best. Robert Nisbet, on the other hand, affords valuable insights into the analytical genius of Durkheim in his 1974 book, The Sociology of Emile Durkheim.5 I single out this author as a guide to discovering what may be profitable in Durkheim because Nisbet was a brilliant intellectual historian who saw European history in terms of the decline of morally bound groups. Durkheim's celebrated 1897 study on suicide anticipated this conclusion when the author signaled "moral poverty" and anomie as causal factors in the occurrences of suicide in nineteenth-century Europe.6 Max Weber (1864–1920) brought his peculiar style of idealist or antipositivist reflection to bear on the relationship between the sacred, religion, and morality. His promotion of the fact-value distinction led Leo Strauss to consider Weber the most profound exponent of values relativism in social science.7 The American political scientist Rogers Brubaker expounds on Weber's views and, [End Page 17] in general, the positivist basis of modern culture and society in The Limits of Rationality, An Essay on the Social and Moral Thought of Max Weber.8 Although Durkheim and Weber each develops his own approach to the role that religion plays in secular society, these two thinkers are generally accepted as the forgers of the functional empiricism that governs the epistemological outlook of the modern social sciences. This outlook today affects profoundly the way that Christian believers, especially Catholics, think about God, religion, and, to be sure, morality.9 One way to evaluate the influence that modern sociology has exercised on Catholics in the United States is to observe the evolution from its founding in 1938 of the American Catholic Sociological Society (ACSS) into its present-day embodiment as the Association for...

Nature of intergrain bonding upon compaction of ultrahigh-molecular-weight polyethylene reactor powders

165 Undoubted advantages of methods for obtaining high-strength filaments and fibers directly from reactor powders (without preliminary melting and/or dissolution) are their environmental friendliness and reduced energy consumption. Studies of the mechanism of transformation of compacted reactor powders (CRPs) into an ultrahigh-strength oriented material point to a decisive role of cohesive bonds between grains. Their formation is caused by deformation, diffusion, and recrystallization in the boundary layers of neighboring grains upon compaction [1‐4]. To some extent, analogous processes inevitably proceed in the interior of grains, although the complete failure of the native structure of reactor powder grains, for example, on remelting, renders the attainment of high draw ratios impossible [5]. The lack of a direct method of identification of cohesive bonds between grains makes it impossible not only to develop theoretical models of deformation of heterogeneous systems but also to control the density of a network of cohesive bonds between grains during optimization of the processes of fabrication of ultrahigh-strength materials based on UHMWPE reactor powders. In this work, we identified for the first time such cohesive bonds between grains in study of the deformation of CRPs in adsorption-active liquid media. At room temperature, CRP samples in which consolidation was intentionally not completed can undergo brittle fracture at small strains [4]. The tensile properties of such materials in air are mainly determined by the physical and cohesive bonds at the intergrain boundaries, where fracture cracks are nucleated. Under these conditions, it is difficult to separate out the contribution of cohesive bonds to the total strength of a heterogeneous system. However, as is known [6], the interfacial surface energy γ sl at the boundary with the medium has a crucial effect on fracture of solids (the Rehbinder effect). By using physically active (adsorption-active) media, the strength of physical bonds between the units of a heterogeneous system can be considerably changed. At the same time, similar media have no direct effect on the strength of chemical bonds. This has allowed us to suggest that deformation in liquid media will provide the possibility to separate the “physical” and “chemical” components of strength in PE CRPs, i.e., to identify intergrain cohesive bonds and determine the density of their network. In this paper, we report the results of our studies in this direction. As distinct from low-molecular-weight compounds, the fracture of polymers is inevitably associated with the displacement and/or rupture of polymeric chains. The rupture of cohesive bonds sharply increases the fracture work, and the relationship between γ sl and

Antecedent Moisture Content and Aging Duration Effects on Seal Formation and Erosion in Smectitic Soils

Soil susceptibility to seal formation and erosion depends on its inherent properties and surface conditions. Our objective was to study the interaction of two different surface conditions, antecedent moisture content (AMC) and aging duration, on seal formation and erosion in four smectitic soils. Soil samples were packed in trays and wetted with different amounts of water (0, 1, 2, 3, 4, 6, 8, or 16 mm) with a mist type rain. The wetted samples were put in plastic bags and allowed to age for 0.01, 1, 3, or 7 d. The soil trays were exposed to 60 mm of distilled water rain of high energy. At no aging (0.01 d), runoff volume (a measure for seal development) and soil loss increased with an increase in AMC mainly because of enhanced slaking. In general, runoff and soil loss decreased with the increase in aging duration. For instance, in the Clay (Y) soil, to which 3 mm of water was added, as aging increased from 1 to 7 d, runoff decreased from 39 to 28 mm, and soil loss decreased from 660 to 397 g m2 For any given aging duration, the smallest runoff volume and soil loss were obtained at the intermediate AMC levels (2, 3, and 4 mm of water added); at this AMC range, increasing aging time resulted in up to 40% decrease in runoff or soil loss. The effects of aging at these AMC levels (generally between wilting point and field capacity [i.e., pF 4.1–2.4]) were significantly more pronounced for clay soils probably because at these AMCs water‐filled pores in the clay fabric were considered active in the stabilization process and the development of cohesive bonds between and within particles during the aging period. Soil erosion changed with the increase in aging duration in a manner similar to runoff, suggesting that runoff was the main precursor to erosion under these conditions.

Effects of Air Void Size Distribution, Pore Pressure, and Bond Energy on Moisture Damage

Abstract The relationship between hot mix asphalt moisture damage, air void structure, pore pressure, and cohesive and adhesive bond energies was investigated in this study using mixes with two different aggregate types (limestone and granite). Each of the mixes was designed with varying gradations to obtain different air void distributions among specimens. Moisture damage was evaluated using parameters derived based on the principles of fracture mechanics. Air void distribution was analyzed using a probabilistic approach with the assistance of X-ray computed tomography and image analysis techniques. The cohesive and adhesive bond energies of the mix were calculated using experimental measurements of aggregate and asphalt surface energies. Permeability, which controls the ability of the water to infiltrate into and drain out of the mix, was expressed as a function of statistical parameters of the air void distribution. Ranges of air void distributions and permeability were identified for each of the limestone and granite mixes at which moisture damage was maximum. The difference in moisture damage between the granite and limestone mixes was explained based on air void distribution and cohesive and adhesive bond energies.

Simple Method for Predicting Laboratory and Field Permeability of Hot-Mix Asphalt

The infiltration of water in asphalt pavements promotes moisture damage, primarily by damaging the binder cohesive bond and the adhesive bond between aggregates and binder. The first step in addressing the problems caused by the presence of water within pavement systems is quantifying the permeability of hot-mix asphalt (HMA) mixes. A simple equation for predicting the permeability of HMA has been developed. This equation includes parameters that quantify percentage air voids, aggregate gradation, and asphalt binder content. Pavement engineers can use this formula to design asphalt mixes that exhibit acceptable levels of permeability. A comprehensive database of materials and laboratory and field permeability measurements was used to calibrate the equation. Consequently, the ability of the equation to predict the permeability of field cores that were not used in the calibration process was verified. Included is an example illustrating the usefulness of the equation in estimating the permeability distribution in asphalt pavements by using mix properties.

Simple Method for Predicting Laboratory and Field Permeability of Hot-Mix Asphalt

The infiltration of water in asphalt pavements promotes moisture damage, primarily by damaging the binder cohesive bond and the adhesive bond between aggregates and binder. The first step in addressing the problems caused by the presence of water within pavement systems is quantifying the permeability of hot-mix asphalt (HMA) mixes. A simple equation for predicting the permeability of HMA has been developed. This equation includes parameters that quantify percentage air voids, aggregate gradation, and asphalt binder content. Pavement engineers can use this formula to design asphalt mixes that exhibit acceptable levels of permeability. A comprehensive database of materials and laboratory and field permeability measurements was used to calibrate the equation. Consequently, the ability of the equation to predict the permeability of field cores that were not used in the calibration process was verified. Included is an example illustrating the usefulness of the equation in estimating the permeability distribution in asphalt pavements by using mix properties.

Decomposition in as-grown (Ga,In)(N,As) quantum wells

We report on the investigation of the local element distribution in as-grown (Ga,In)(N,As) quantum wells with high In and N contents by using low-loss electron energy-loss spectroscopy combined with dark-field transmission electron microscopy. The (Ga,In)(N,As) quantum wells were grown on GaAs(001) substrates at different growth temperatures by molecular-beam epitaxy. Lateral modulations on the nanometer scale were detected with reversal In and N distributions pointing to the existence of regions with a more favorable Ga–N and In–As bond configurations, respectively. These composition fluctuations are the driving force for the morphological instabilities at the interfaces. Lowering the growth temperature of the quantum well results in a more homogeneous element distribution of the quaternary compound. This result is discussed with regard to the influence of the epitaxial strain and cohesive bond energy on the alloy formation during epitaxial growth.

More than a separase

Anaphase onset is triggered when the protease separase cleaves the cohesive bond that holds replicated sister chromatids together until metaphase. In budding yeast, separase then also regulates mitotic exit. New findings suggest that in vertebrates, separase also participates in cell-cycle regulation, albeit in an unexpected manner.

Improvement of fluidizability of fine powders — a computer study

Simulations of the gas fluidization of a cohesive powder were performed using the Stokesian Dynamics method and an agglomeration-deagglomeration model to investigate methods of improving the fluidizability of fine powders. Three techniques (a) high gas velocity (b) vibration-assisted fluidization and (c) tapered fluidizer were used in the simulations which provided detailed information on the bed microscopy such as the motion of 100 particles in a fluidizing vessel along with the formation and destruction of cohesive bonds during collisions. While all three techniques were found to effectively improve the fluidizability of a strongly cohesive powder, we suggest a combination of high velocity fluidization assisted by external vibration of the fluidized bed to minimize entrainment of particles.

Soft-ratchet modeling of end-point memory in the nonlinear resonant response of sedimentary rocks

We developed and thoroughly examined a model of longitudinal vibrational resonance in bar-shaped sedimentary rocks; these materials exhibit memory that originates from an essential asymmetry in processes of rupture and recovery of intergrain and interlamina cohesive bonds. The theory relies on an appropriate isolation and an adequate formalization of two mutually dependent subsystems, namely, a subsystem of ruptured bonds and a subsystem of internal longitudinal displacements. The subsystem of ruptured bonds is shown to be of a soft-ratchet type, so that its response to an alternating internal stress is characterized by broken symmetry and appears as nonzero long-term temporal and spatial changes in the concentration of ruptured bonds. The internal stress is generated by an alternating external drive acting both directly through the subsystem of longitudinal displacements and indirectly through temporal and spatial modifications of Young's modulus due to changes in concentration of ruptured bonds. The scheme reproduces the main experimental effects by using the simplest linear form of attenuation in an elastic subsystem and realistic assumptions about the stress-strain relation. In particular, it correctly describes: hysteretic behavior of a resonance curve on both its upward and downward slopes; linear softening of resonant frequency with increase of driving level; gradual (almost logarithmic) recovery (increase) of resonant frequency at low dynamical strains after the sample was conditioned by high strains; and temporal relaxation of response acceleration amplitude at fixed frequency. These are the most interesting observations typical of forced longitudinal oscillations of sandstone bars in the nonlinear regime. Further, we are able to trace how water saturation enhances the hysteresis and simultaneously decreases the quality factor because of an increase in equilibrium concentration of ruptured cohesive bonds. We also predict theoretically a dynamical effect analogous to the widely known quasistatic effect of hysteresis with discrete (end-point) memory.