The Reception and Sources of Berenice Abbott's Paris Portrait Style, 1925–1929

This study focuses on the photographs that first brought Berenice Abbott critical acclaim: her Paris portraits from the late 1920s. As a body of work, these images – along with what Abbott had to say about them and the critical attention they generated at the time – provide a rich resource for the study of three interconnected topics: the avant-garde critical climate of Europe in the late 1920s, the American expatriate experience in Paris during this same time and Abbott's nascent photographic values and aesthetic, which helped to inform not only her portraits but also her later, better-known photographs of New York City. The paper first defines the divergent critical responses to Abbott's portrait work in the late 1920s – focusing especially on the published criticism by Florent Fels and Pierre Mac Orlan that helped to secure Abbott's international reputation as a leading modern photographer. It then turns to Abbott's expatriate experience in order to examine the ideas and individuals that she identified as most important to her photographic practice. Specifically the paper explains Abbott's desire to create an alternative approach to photography from the one used by Man Ray, her awareness of the classical style associated with Pablo Picasso and her admiration for the aesthetic theories of Leo Stein.     

The shape of a Möbius strip

The M?bius strip, obtained by taking a rectangular strip of plastic or paper, twisting one end through 180 degrees, and then joining the ends, is the canonical example of a one-sided surface. Finding its characteristic developable shape has been an open problem ever since its first formulation in refs 1,2. Here we use the invariant variational bicomplex formalism to derive the first equilibrium equations for a wide developable strip undergoing large deformations, thereby giving the first non-trivial demonstration of the potential of this approach. We then formulate the boundary-value problem for the M?bius strip and solve it numerically. Solutions for increasing width show the formation of creases bounding nearly flat triangular regions, a feature also familiar from fabric draping and paper crumpling. This could give new insight into energy localization phenomena in unstretchable sheets, which might help to predict points of onset of tearing. It could also aid our understanding of the relationship between geometry and physical properties of nano- and microscopic M?bius strip structures.     

The invention and reinvention of Martín Chambi

Abstract

Distanced by over fifty years, Latorre and Thornton offer opposing perceptions of Martin Chambi as an artist.3 This is an abbreviated version of chapter four from my doctoral dissertation, Rethinking Martín Chambi, completed in 1997 at the University of New Mexico. Roberto Latorre, writer for and editor of the intellectual journal Kosko, was an integral part of the cultural milieu of 1 920s Cusco, Peru, where Chambi lived and worked. His statement was part of a review of Chambi's exhibitions from around 1925. Gene Thornton, photography critic at the New York Times during the 1970s, judged Chambi from pictures exhibited at the Museum of Modern Art in 1979. Both critics reflect the aesthetic sensibilities of their time and the context in which they were writing: what are we to make of such disparate interpretations of the same photographer, including the shift from Latorre's emphasis on Chambi's landscapes to Thornton's interest in his portraits? At issue is the difference between Chambi's sense of himself as an artist during his own life, and how that sense was reshaped when Chambi was rediscovered after his death in 1973.     

The121Sb Mössbauer spectra of antimony-containing glasses

The¹²¹Sb Mössbauer spectra of a series of Na₂O-B₂O₃-Sb₂O₃, (Na₂O, 2P₂O₅) + Sb₂O₃, and (Na₂O, 2SiO₂) + Sb₂O₃ glasses have been measured. The chemical isomer shifts,, and the quadrupole couplings,eQV _zz, for antimony (III) in different glasses have been estimated. From the changes of isomer shift is has been deduced that the ionicity of the Sb-O bond increases with decreasing Na₂O content in Na₂O-B₂O₃-Sb₂O₃ glasses; and when the network former is changed, with equivalent molar composition, the ionicity of the Sb-O bond increased in the order borate silicate < phosphate.     

The effect of the methods of preparation on the Mössbauer spectrum of an Fe-Ge intermetallic compound

A comparative study was carried out on the effect of the methods of preparation on the Mössbauer spectrum of the -Fe₅Ge₃ phase. The disagreements between the various reported spectra for the -phase can be attributed to variations in the stochiometry of the final product. Sintering seems to be the best way to prepare the -phase, while melting of the iron-germanium powders resulted in evaporation and considerable loss of germanium. The various methods of preparation were subjected to chemical analysis and X-ray diffraction.     

The state of iron in natural zeolites: A Mössbauer study

The state of iron in natural zeolites is an important feature for the practical applications of these materials. A Mössbauer study, complemented with other methods, of iron-containing zeolitic rocks from several countries (Mexico, Cuba, Czechoslovakia, and the USSR) was developed. It has been determined that iron is located as high spin Fe³⁺ in framework tetrahedral sites, in extraframework octahedral sites as free Fe(H₂O)₆³⁺, and as high spin Fe²⁺ in octahedral coordination in extraframework sites or in another aluminosilicate associated with the zeolite. Iron is also located in magnetite contained in the zeolite rocks.     

Dynamics of Polymeric Fluids: Part II The Molecular Theory of Die Swell: Correlation of Ultimate Die Swelling Effect to the Molecular Parameters and the Operational Variables

A general expression for the correlation of the simple shear (tan(?)) to the molecular parameters and the shear rate (γ) was deduced. It shows that the simple shear (tan(?)) may be resolved into free recoil (recoverable strain) and viscous heating (unrecoverable strain). The magnitudes of the simple shears for recoil (tan(?)E) and (tan(?)V) for viscous heating not only depended on the molecular parameters and the operational variables, but also on the exponential fractions of the recoverable (1-Wγ) and unrecoverable (W-γ) conformations for recoil and viscous heating. Therefore the magnitudes of the simple shears (tan(?)E) for recoil and (tan(?)V) for viscous heating are, respectively, expressed as the partition function to the (1-Wγ)th power and the partition function to the (Wγ)th power. Thus correlations of the total recoil and the ultimately recoverable strains to the molecular parameters [n', a,η0, GN0 and (1-Wγ)] and the operational variables (γ, (L/D) and tr) were deduced respectively, which show that at very different shear rates (0≤γ≤∞) the polymeric liquids may exhibit a very different viscoelastic behaviors. After introducing the uniform two-dimensional extension, the definition of swelling ratio and the ratio of L to D [De=(L/D)], two expressions for the ultimate die swelling effect and the ultimate extrudate swelling ratio BEVT5 to the molecular parameters [n', a,η0, GN0 and (1-Wγ)] and the operational variables (γ, (L/D) and tr) were obtained. The two correlation expressions were verified by the experimental data of high-density polyethylene (HDPE) which shows that the two correlation expressions can be used to predict the correlations of the ultimate extrudate swelling behaviors of polymeric liquids to the molecular parameters and the operational variables.     

Dynamics of Polymeric Fluids: Part Ⅱ The Molecular Theory of Die Swell: Correlation of Ultimate Die Swelling Effect to the Molecular Parameters and the Operational Variables

A general expression for the correlation of the simple shear(tanφ)to the molecular parameters and the shear rate(γ)was deduced. It shows that the simple shear(tanφ)may be resolved into free recoil(recoverable strain)and viscous heating(unrecoverable strain). The magnitudes of the simple shears for recoil(tanφE)and(tanφv)for viscous heating not only depended on the molecular parameters and the operational variables,but also on the exponential fractions of the recoverable(1-(W)γ)and unrecoverable((W)γ)conformations for recoil and viscous heating. Therefore the magnitudes of the simple shears(tanφE)for recoil and(tanφv)for viscous heating are, respectively, expressed as the partition function to the(1-(W)γ)th power and the partition function to the(-(W)γ)th power. Thus correlations of the total recoil and the ultimately recoverable strains to the molecular parameters [n', a, η0, G0NN and(1--(W)γ)] and the operational variables(·γ, (L/D)and tr)were deduced respectively, which show that at very different shear rates(0≤·γ≤∞)the polymeric liquids may exhibit a very different viscoelastic behaviors. After introducing the uniform two-dimensional extension, the definition of swelling ratio and the ratio of L to D [De=(L/D)], two expressions for the ultimate die swelling effect and the ultimate extrudate swelling ratio BEVT5 to the molecular parameters [n', a, η0, G0N and(1--(W)·γ)] and the operational variables(·γ,(L/D)and tr)were obtained. The two correlation expressions were verified by the experimental data of high-density polyethylene (HDPE) which shows that the two correlation expressions can be used to predict the correlations of the ultimate extrudate swelling behaviors of polymeric liquids to the molecular parameters and the operational variables.     

Dynamics of Polymeric Fluids：Part Ⅱ The Molecular Theory of Die Swell： Correlation of Ultimate Die Swelling Effect to the Molecular Parameters and the Operational Variables

A general expression for the correlation of the simple shear (tan ) to the molecular parameters and the shear rate ( ) was deduced. It shows that the simple shear (tan ) may be resolved into free recoil (recoverable strain) and viscous heating (unrecoverable strain). The magnitudes of the simple shears for recoil (tan E) and (tan V) for viscous heating not only depended on the molecular parameters and the operational variables, but also on the exponential fractions of the recoverable (1- ) and unrecoverable ( ) conformations for recoil and viscous heating. Therefore the magnitudes of the simple shears (tan E) for recoil and (tan V) for viscous heating are, respectively, expressed as the partition function to the (1- )th power and the partition function to the ( )th power. Thus correlations of the total recoil and the ultimately recoverable strains to the molecular parameters [ , a, η0, GN0 and (1- )] and the operational variables ( ), (L=D) and tr) were deduced respectively, which show that at very different shear rates ( ) the polymeric liquids may exhibit a very different viscoelastic behaviors. After introducing the uniform two-dimensional extension, the definition of swelling ratio and the ratio of L to D [De=(L/D)], two expressions for the ultimate die swelling effect and the ultimate extrudate swelling ratio BEVT5 to the molecular parameters [ , a, η0, GN0 and (1- )] and the operational variables ( , (L/D) and tr) were obtained. The two correlation expressions were verified by the experimental data of high-density polyethylene (HDPE) which shows that the two correlation expressions can be used to predict the correlations of the ultimate extrudate swelling behaviors of polymeric liquids to the molecular parameters and the operational variables.     

Dynamics of Polymeric Fluids 1. The Molecular Theory of Die Swell： A Set of Equation on Swelling Ratio in Extrudates

The structural model of the multiple-transient networks and the mechanism of the multiple-reptation entangled chains due to the dynamic reorganization in the entangled sites were extensively applied on the die swell of polymeric liquids in the steady simple shear flow. The total (recoverable and unrecoverable) viscoelastic free energy of deformation and flow, the constitutive equation and the expression of the simple shear (tanψ)were deduced from the conformational probability distribution function of the entangled polymer chains. It found that: (1) the magnitudes of simple shear (tanψ) depended not only on the free recoil (or recoverable strain) but also on the viscous heating (or unrecoverable strain); (2) the total recoil may be resolved into the instantaneous and delayed recoil. Based on these facts, the functions of the partition and two experiential fractions of the recoverable (1(-W)γ) and the unrecoverable ((-W)γ) conformations for the recoil and viscous heating of polymeric liquids were defined correspondingly. Then the correlation of the instantaneously and ultimately (or total) recoverable strains to the (N1/τ12)w and the fraction of trans-form conformation was obtained. After introducing the condition of uniform two-dimensional extension (αx=αy=α, αz=α-2) and the swell ratio (B=α), two sets of equations on the instantaneous and ultimate swelling ratios (BE, BEVT) were obtained, and a method to determine the fraction of the recoverable transform conformation were proposed.The equations of BE and BE5 were verified by the experimental data of HDPE (high denisity polyethylene)at two different high temperatures. It shows that the molecular theory of die swell can be used to predict the correlation of the swelling to the (N1/τ12)w and the fraction of trans-form conformation.     

The role of iron in the formation of inorganic polymers (geopolymers) from volcanic ash: a 57Fe Mössbauer spectroscopy study

The behavior of the iron present in two volcanic ashes was investigated during geopolymer synthesis using sodium hydroxide as the sole alkali activator. XRD, SEM, and room-temperature ⁵⁷Fe Mössbauer spectroscopy were used to monitor the behavior of the iron during the synthesis reaction. Geopolymers with very good compressive strengths were formed, especially with the finer ash, in which the iron is present in the crystalline minerals ferroan forsterite and augite. Mössbauer spectroscopy identified the ferrous sites in these minerals, plus a ferric site, probably located in an X-ray amorphous phase. The ferroan forsterite in the original ashes did not react with NaOH, but a substantial proportion of the augite reacted to form new ferric sites with parameters similar to distorted tetrahedral or 5-coordinated environments, suggesting the possible incorporation of ferric iron in the tetrahedral network of the geopolymer product. These results indicate that iron is not necessarily deleterious to geopolymer formation, as has sometimes been suggested.     

Carbon Cage Vibrations of M@C82 and M2@C2 n (M = La,Ce; 2n = 72, 78, 80): The Role of the Metal Atoms

Infrared spectra of La₂@C₈₀ and a series of Ce-based endohedral metallofullerenes (EMFs), including Ce@C₈₂, Ce₂@C₇₂, Ce₂@C₇₈, and Ce₂@C₈₀ are reported. DFT calculations are used for their thorough analysis and assignment. The vibrations of the fullerene cages in all studied EMFs differ from those of their empty, charged cage analogues. Furthermore, EMFs with the same carbon cage but different type of encapsulated species also show significant differences in their cage vibrational patterns. These phenomena are explained by a different coupling of the vibrational modes as well as by the different charge distributions in EMFs and empty, isostructural fullerene anions.     

The nonlinear optical, magnetic, and Mössbauer spectral properties of some iron(III) doped silica xerogels

Iron(III) species dispersed in silica have been synthesized with a sol-gel process. The iron(III) was introduced as the acetylacetonate complex into a solution of tetraethoxysilane to yield, after evaporative drying, pellets or monoliths. Two gels were dried very slowly over a period of five months in order to prepare a defect free monolith useful for nonlinear optical studies. Z-scan experimental studies on the resulting, transparent, monolithic, doped solid revealed an optical Kerr effect, a third order nonlinear optical phenomenon showing a linear dependence of the refractive index on the irradiance with a nonlinear refractive index, n ₂ , of ?1.95 × 10^?11 cm²/W. Magnetic susceptibility studies between 4.2 and 295 K revealed paramagnetic behavior with a Curie constant of 4.433 (emu/mol)K and a Weiss temperature of ?7.1 K. Magnetization studies at 5 K and at applied fields of up to 4 T and Mössbauer spectral studies between 4.2 and 295 K revealed a 50:50 mixture of paramagnetic species and nanoparticles with an average particle radius of 1.3 ± 0.2 nm. A blocking temperature of 70 K and a magnetic anisotropy energy of 2.4 × 10⁵ J/m³ are derived from the Mössbauer spectra.     

The interfacial structure of nanocrystalline Fe73.5Cu1Mo13Si13.5B9 studied by Mössbauer spectroscopy

Nanocrystalline Fe_73.5Cu₁Mo₃Si_13.5B₉ prepared by crystallization of the amorphous alloy was investigated by using Mössbauer spectroscopy and X-ray diffractometry. The present study focuses on the interfacial composition and the important role of the interfacial component in the development of the nanocrystalline structure. On the basis of a newly developed fitting program, the amorphous phase is denoted by a low field component and a high field one. Upon crystallization, the former, which corresponds to the boundary regions adjacent to the grains become more significant. The different stages associated with the crystallization are discussed.     

Absolute instability of the von Kármán, Bödewadt and Ekman flows between a rotating disc and a stationary lid

The stability of a family of boundary-layer flows, which includes the von Kármán, B?dewadt and Ekman flows for a rotating incompressible fluid between a rotating disc and a stationary lid, is investigated. Numerical computations with the use of a spectral method are carried out to analyse absolute and convective instability. It is shown that the stability of the system is enhanced with a decrease in distance between the disc and the lid.     

Reactions of alcohols with hydrogen sulfide over zeolites: Part V. The role of Brönsted acid sites in thiols formation — A comparative study of zeolites and heteropoly acids

The activity and selectivity of Me²⁺ NaX zeolites (Me = Cd, Zn, Ni, Co) and free and supported heteropoly acids (HPA) for hydrosulfurization of n- and i-PrOH have been investigated. The influence of concentration and strength of Brönsted acid centers on the yield of thiols is discussed on the basis of comparative measurements carried out on zeolites and HPA. The effect of H₂S chemisorption on the selectivity of hydrosulfurization process is considered.     

The Modified Wöhler Curve Method calibrated by using standard fatigue curves and applied in conjunction with the Theory of Critical Distances to estimate fatigue lifetime of aluminium weldments

This paper is concerned with the application of a novel engineering method we have recently devised to estimate fatigue lifetime of aluminium welded joints subjected to constant-amplitude uniaxial and multiaxial fatigue loading. The assessment technique employed in the present study is based on the use of the so-called Modified Wöhler Curve Method (MWCM), a conventional critical plane approach, applied in conjunction with the theory of critical distances (TCD). In more detail, the MWCM was initially calibrated by using two standard curves: the first one, stated by Eurocode 9, suitable for assessing ground butt welds subjected to uniaxial loading, whereas the second one, suggested by the International Institute of Welding (IIW), suitable for estimating fatigue strength of aluminium welded details loaded in torsion. Subsequently, a unifying critical distance value to be performed to assess aluminium welded joints was calculated by taking full advantage of the master curve supplied by the notch-stress intensity factor (N-SIF) approach and obtained by summarising the uniaxial fatigue strength of cruciform aluminium welded details characterised by different absolute dimensions. Finally, the accuracy and reliability of the devised method was systematically checked by means of several experimental results taken from the literature and generated by testing a variety of welded geometries subjected to uniaxial as well as to multiaxial fatigue loading. Such an extensive validation exercise allowed us to prove that our approach is successful in estimating fatigue damage in aluminium welded details, resulting in predictions mainly falling within the two reference scatter bands adopted to calibrate the method itself. Such a high accuracy level is very promising, especially in light of the fact that our engineering approach can be applied to assess real aluminium welded components by directly post-processing simple linear-elastic finite element (FE) models.