Hansen's Theory Research Articles

Solubility of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) in sustainable and green solvents: Effect of HV content and comparison between experimental results and theoretical prediction

For the first time, a quantitative analysis of the solubility of poly-3hydroxybutyrrate-co-3hydroxyvalerate (PHBV) in green solvents is proposed. The solubility of two commercial co-polymers, with hydroxyvalerate (HV) contents of 8 %mol and 12 %mol, in 1,3-dioxolane, dimethyl carbonate and butyl acetate was experimentally determined using chloroform as the benchmark and water as the control. The results showed a direct correlation between solubility and temperature, with a maximum at the boiling point of the solvent. For PHBV with an HV content of 8 %mol, solubilities of 265 mg mL−1 for 1,3-dioxolane and dimethyl carbonate and 274 mg mL−1 for butyl acetate were measured; for PHBV with an HV content of 12 %mol, solubilities of 225 mg mL−1, 197 mg mL−1 and 137 mg mL−1 for 1,3-dioxolane, dimethyl carbonate and butyl acetate were measured, respectively. Following Hansen's theory, the PHBV solubility sphere was defined to predict the solubility of the co-polymers in solvents qualitatively. The validation of the sphere was performed by the experimental results herein obtained.

Some factors affecting pore size in the synthesis of rigid polymer monoliths: Theory and its applicability

AbstractMacroporous monoliths represent now widely used materials whose successful application strongly depends on their characteristics. Among those the average pore size is one of the key parameters. In this paper, we consider the applicability of theoretical calculations for the selection of appropriate porogens to generate the materials with required average pore size. A set of macroporous poly(meth)acrylate monoliths was synthesized via thermo‐ and photo‐initiated free radical polymerization and characterized in regards to their average pore size. Additionally, the difference in solubility parameters as well as Hansen's solubility parameter distance between monomers and porogens were calculated for each polymerization mixture using Hildebrand's and Hansen's solubility theories. The theoretical predications and experimental data were compared and analyzed to establish the applicability of theoretical calculations to previse average pore size for different systems. It was found that Hildebrand's theory seems to be poorly appropriate as universal tool, while Hansen's theoretical approach explained better the efficiency of solvents as porogens. The application of oligomers and polymer solutions due to the increase of viscosity as well as the variation of crosslinker amount in the monomer system can be singled out as Hansen's theory limitations at the prediction of the average pore size.

Transition Energy, Spectral Fine Structure, and Absorption Coefficient of Norbixin (9’-cis-6,6’-diapocarotene-6,6’dioic acid) in Different Polar Solvents

Transition energy, spectral fine structure, and absorption coefficient of norbixin in different polar solvents has been investigated. Eight polar solvents were used for dissolving norbixin separately, including methanol, ethanol, propylene carbonate, acetone, dichloromethane, ethyl acetate, chloroform, and dimethyl carbonate. Spectra of norbixin in the resulting solutions were determined by UV-visible spectrophotometry at atmosphere condition. The effect of solvents on transition energy was analyzed according to Onsager cavity model and Hansen theory. The approximate absorption coefficient was determined with the Beer-Lambert law. The result show that the UV-visible absorption spectra of norbixin depend onz the solvent. The greater the refraction index of the solvent and the norbixin-solvent dispersion interaction cause the transition energy of norbixin was smaller. The change in spectral fine structure has some relevance or correlation with the solvatochromic effect on π → π* transitions, the intermolecular interactions, and the S2 state of norbixin. The absorbance of norbixin in various solvents, increased linearly with concentration.

The Hansen theory to choose the best cosolvent for supercritical CO2 extraction of β-carotene from Dunaliella salina

The Hansen solubility theory was used to predict the best cosolvent for supercritical carbon dioxide (sc-CO2) to achieve the selective extraction of β-carotene from Dunaliella salina. Among four organic cosolvents, ethanol was predicted to be the best based on minima Ra values. The predictions were validated through equilibrium data and extraction curves from the microalgae. The addition of ethanol reduced the bubble pressures, and therefore increased the solubility of the β-carotene. With 5% mass fraction, at 318.15 K and 20 MPa, the extraction yield was 25 g carotenoids kg microalgae−1, much more than in pure sc-CO2 (6 g).

Prediction of the best cosolvents to solubilise fatty acids in supercritical CO2 using the Hansen solubility theory

Cosolvents are employed to improve the extraction efficiency and modify the selectivity of the main solvent. However, choosing a proper cosolvent in supercritical extraction is an arduous task. This study aimed to predict the best cosolvents for the supercritical CO2 extraction of oleic and linoleic acids using the Hansen solubility theory. Calculations were performed for eight organic cosolvents used in food and pharmaceutical production. The best cosolvents for the solubilization of both fatty acids were short-chain alcohols, ethanol and methanol. The predictions were validated with bubble pressures of the mixtures with a 0.003 fatty acid molar fraction at temperatures of 313.2 K and 323.2 K. The experimental results agreed with the predictions. The effect of pressure was well predicted via the direct relationship between pressure and the solvent density. However, the impact of temperature was not properly foreseen because the variation of solute vapour pressure was not considered. The Hansen theory predicted that the miscibility enhancement of the solute in the supercritical mixture is maximum at low pressures and low cosolvent concentrations, as was experimentally confirmed.

Hansen theory applied to the identification of nonhazardous solvents for hybrid perovskite thin-films processing

Metal-halide perovskites have become the most studied material for efficient next-generation solar cells, in part because of the possibility of depositing high quality semiconducting perovskites by simple solution-based methods. However, the majority of solvent systems implemented in literature for deposition of lead halide perovskites are hazardous to handle. Investigation of alternatives perovskite processing methods are hence key to safely upscale the perovskite photovoltaic manufacturing.In this manuscript we use the Hansen theory to find suitable nonhazardous solvents to solubilize two lead salts, PbBr2 and PbI2, used to fabricate the corresponding methylammonium (MA) lead halide perovskite films. The method is based on the use of the Hansen solubility parameters (HSPs) of a lead salt and a solvent to provide insight into whether interactions between them are favorable or not. We first studied the solubility properties of each lead salt (PbBr2 and PbI2) by determining experimentally their Hansen solubility spheres. Using these results, computer simulations allow us to determine compatible nonhazardous solvents with these two compounds in terms of solubility. We further investigated the use of a nonhazardous diester blend polar solvent to deposit MAPbI3 and MAPbBr3 thin films.

What Marx Means Today

Marx made significant contributions to macroeconomics, laying the grounds for both Keynes's theory of aggregate demand and Schumpeter's theory of creative destruction. His law of the tendency of the rate of profit to fall parallels Alvin Hansen's theory of secular stagnation which has recently received much attention among scholars studying the financial crises in Japan, the US and the Eurozone. This article argues that part of the new stagnation does not result from a natural exhaustion of investment possibilities, but from an overly loose central bank monetary policy that keeps zombie banks and their zombie clients alive and blocks the emergence of new start-up firms.

Hansen Solubility Parameters of Coal Tar-Derived Typical PAHs Using Turbidimetric Titration and an Extended Hansen Approach

The advantage of selectivity for coal tar extraction can be obtained by using the solubility parameter of Hansen theory as a guide. However, most of the Hansen solubility parameters (dispersion contributions, δd; polarity contributions, δp; hydrogen bonding contributions, δhb) of coal tar components (e.g., polycyclic aromatic hydrocarbons, PAHs) were inadequate. This study estimated the Hansen solubility parameters of naphthalene, acenaphthene, anthracene, phenanthrene, pyrene, and fluoranthene from coal tar by applying a new approach regulated by turbidimetric titration and a calculating program based on the method of exhaustion. The extended Hansen approach was used to verify the new approach and evaluate the solubility of the six PAH components in different solvents. The results show that the new method can clearly identify the differences in Hansen solubility parameters caused by various combinations of benzene rings among some isomers (e.g., anthracene and phenanthrene). Among the six PAH compounds, ...

Preserving the Open Form. The Oskar and Zofia Hansen House in Szumin: Between architecture and contemporary art

A wooden summer house in Szumin, built between 1969 and 1970, is a spatial manifesto for the Open Form — a theory formulated by Polish architect, artist, and educator Oskar Hansen (1922–05). Oriented towards participation, process, and change in the hierarchy between the architect and the user, or the artist and the spectator, Hansen's theory formed a strong conceptual basis for his architectural, artistic, and pedagogical practice. Being a faithful expression of these ideas, the house is a spatio-temporal, transitional object, defined by constant adaptation to the changing needs of its users. In 2014 the property came into the custody of the Museum of Modern Art in Warsaw, Poland. A conservation strategy was developed to preserve both the idea and the physical aspect of the site. With its dominance of concept and artist's intent, this house has a stronger resemblance with a work of art than with built heritage. Therefore, the procedures developed for the conservation of contemporary artworks have been applied. These tools help to evaluate the range of necessary interventions and to set up a conservation programme.

Richard Hansen and modern planting design

Richard Hansen's planting design, following garden habitats, is said to be an approach equally uniting ecology and design (Fig. 1). Common opinion understands ecological planting design as utilizing only native plants—an approach often seen as having been rooted in National Socialist ideology. This, however, is a misconception, which will be demonstrated by discussing Alwin Seifert's ideas of bodenständig (down-to-earth) planting design. Consequently, through his concept of garden habitats, Hansen implements the requirements of Bodenständigkeit (‘down-to-earthedness’). In addition to functionality, this includes in particular the integration of foreign species of plants within horticulture through the use of plant sociology. This provided Hansen with scientific backing for his planting design in the garden. His concept differs significantly from approaches of other important personalities in German planting design, such as Willy Lange, Alwin Seifert, or the subsequent Nature Garden movement of Le Roy or Urs Schwarz. To understand the originality of Hansen's theory it is necessary to discuss his use of the term Bodenständigkeit—a term relevant for the time in which he operated. Garden habitats can be discussed in the context of landscape character (as in the works of Willy Lange), or under the relevance of site conditions in the contemporary meaning of the term (soil, water, climate) as used by Hansen (Fig. 2). Although Hansen declares native plants as bodenständig, just as his teacher Tüxen did, he proclaimed that foreign plants should be introduced in the garden to create artificial plant(ed) communities, derived from the examples of natural plant associations and thereby decreasing maintenance work. Hansen conducted extensive long-term plant trials to be able to differentiate garden habitats for numerous perennial plants. Hansen's main work, Die Stauden und ihre Lebensbereiche (Perennials and Their Garden Habitats), originates from 1981; it is still in print today and was translated into English in 1993.

Notes from the Editors, January 2016

<div class="buynow"><a title="Back issue of Monthly Review, January 2016 (Volume 67, Number 8)" href="http://monthlyreview.org/product/mr-067-08-2016-01/">buy this issue</a></div>Prabhat Patnaik's Review of the Month in this issue addresses problems of economic stagnation and imperialism in the context of explaining the current global crisis. Patnaik is part of a broad tradition of Marxian thought and heterodox economic analysis more generally that has long focused on issues of economic stagnation under monopoly capitalism. Such questions are now finally being taken up even by orthodox economists, but in ways that systematically ignore decades of contributions in this regard made by heterodox theorists. Ever since Larry Summers raised the issue of secular stagnation (referring back to Alvin Hansen's theory of the 1930s and '40s) at an IMF meeting in 2013, the question of stagnation has become part of a worldwide economic debate, moving issues that were once on the margins to center stage. This has resulted in a proliferation of mainstream economic treatments of the history of the secular stagnation concept in the 1930–1950s period, after which mainstream economists had essentially declared the issue dead.<p class="mrlink"><p class="mrpurchaselink"><a href="http://monthlyreview.org/index/volume-67-number-8" title="Vol. 67, No. 8: January 2016" target="_self">Click here to purchase a PDF version of this article at the <em>Monthly Review</em> website.</a></p>

Generalized failure envelope for caisson foundations in cohesive soil: Static and dynamic loading

The response of massive caisson foundations to combined vertical (N), horizontal (Q) and moment (M) loading is investigated parametrically by a series of three-dimensional finite element analyses. The study considers foundations in cohesive soil, with due consideration to the caisson-soil contact interface conditions. The ultimate limit states are presented by failure envelopes in dimensionless and normalized forms and the effects of the embedment ratio, vertical load and interface friction on the bearing capacity are studied in detail. Particular emphasis is given on the physical and geometrical interpretation of the kinematic mechanisms that accompany failure, with respect to the loading ratio M/Q. Exploiting the numerical results, analytical expressions are derived for the capacities under pure horizontal, moment and vertical loading, for certain conditions. For the case of fully bonded interface conditions, comparison is given with upper bound limit equilibrium solutions based on Brinch Hansen theory for the ultimate lateral soil reaction. A generalized closed-form expression for the failure envelope in M–Q–N space is then proposed and validated for all cases examined. It is shown that the incremental displacement vector of the caisson at failure follows an associated flow rule, with respect to the envelope, irrespective of: (a) the caisson geometry, and (b) the interface conditions. A simplified geometrical explanation and physical interpretation of the associativity in M-Q load space is also provided. Finally, the derived failure envelope is validated against low (0.67Hz) and high frequency (5Hz) dynamic loading tests and the role of radiation damping on the response of the caisson at near failure conditions is unraveled.

Thermodynamic Studies on Polyvinylpyrrolidone Solution Systems Used for Fabrication of Electrospun Nanostructures: Effects of the Solvent

ABSTRACTIn this research, we investigate the influence of polyvinylpyrrolidone (PVP) solution systems on the morphology of the PVP nanofibers fabricated by electrospinning of PVP solutions prepared in different organic solvents, including ethanol (EtOH), propanol (PrOH), chloroform, N‐methyl‐2‐pyrrolidone (NMP), and N,N‐dimethylformamide (DMF) and then compared with the experimental results. First, by considering the electrospun solutions behavior, the thermodynamic studies were evaluated then Hansen solubility theory was applied to select the desirable solvent systems. The dissolving power of the solvents for PVP was obtained in the following order: DMF > NMP >> chloroform > PrOH > EtOH. It seems that every solvent, which is able to dissolve PVP polymer, shows different spinning characteristics under identical conditions of processing parameters. By using PrOH, chloroform, and NMP solvents, electrospun nanofibers’ average diameter was decreased intensively but at the same time beads formation was observed. We investigated that EtOH was a desirable solvent for PVP to fabricate fibers with z micrometer diameter distribution, but because of its low dissolving power it is suitable for microfiber synthesis with the electrospinning process. Based on the Hansen theory and experimental results, the PVP/DMF solutions showed desirable characteristics for the electrospinning system. Furthermore, the PVP nanofiber's uniformity of the PVP/DMF solution was higher than other solvent systems, which mean that fiber diameter distribution is scanty than others. Finally, it has been demonstrated that with an appropriate solvent the nanofiber diameter distribution and formation of beads can be controlled by Hansen theory.

Aprotic solvents effect on the UV–visible absorption spectra of bixin

We describe here the effects of aprotic solvents on the spectroscopic characteristics of bixin. Bixin was dissolved in dimethyl sulfoxide, acetone, dichloromethane, ethyl acetate, chloroform, dimethyl carbonate, cyclohexane and hexane, separately, and its spectra in the resulting solutions were determined by UV–visible spectrophotometry at normal pressure and room temperature. We analyzed the effect of aprotic solvents on λmax according to Onsager cavity model and Hansen theory, and determined the approximate absorption coefficient with the Beer–Lambert law. We found that the UV–visible absorption spectra of bixin were found to be solvent dependent. The S0→S2 transition energy of bixin in solution was dependent principally on the refractive index of the solvents and the bixin–solvent dispersion interaction. There was a small influence of the solvents dielectric constant, permanent dipole interaction and hydrogen bonding occurred between bixin and solvents. The absorbance of bixin in various solvents, with the exception of hexane, increased linearly with concentration.

“A Vibrating Art in the Air”: Cinema, Ether, and Propaganda Film Theory in Wartime Chongqing

This article revisits Miriam Hansen's theory of vernacular modernism by putting it in dialogue with wartime Chongqing propaganda film theory. Comparing key points of parallel between Hansen's dual interest in the linguistic and sensorial function of cinema and Chongqing propaganda film theory, Bao situates the latter in light of changing conditions for film production and exhibition in a wartime media ecology. She pursues how the propaganda fantasy of cinema as a vibratory medium and as a nonneutral, pervasive social milieu inherits historical conceptions of ether developed in Chinese political philosophy since its introduction in the mid-nineteenth century. In the end she teases out a new understanding of cinema as well as an alternative definition of the medium that suggests a new way for us to understand Hansen's investment in vernacular modernism and the stakes it involves.

Notes from the Editors, January 2014

buy this issueOn November 16, 2013, Paul Krugman published a piece on his New York Times blog entitled "Secular Stagnation, Coalmines, Bubbles, and Larry Summers," consisting of an extended commentary on former Clinton Treasury Secretary and Obama economic advisor Lawrence Summers's November 8 presentation to the IMF's Economic Forum.… Krugman, in following up on Summers's IMF speech, highlighted Alvin Hansen's theory of secular stagnation in the 1930s to '50s.… [acknowledging that] long-term economic stagnation…was now "the norm" for the economy, not the exception.… Writing in a fashion that could have come straight out of Monthly Review at any point in the last forty years, he declared: "We now know that the economic expansion of 2003–2007 was driven by a bubble. You can say the same about the later part of the 90s expansion; and you can in fact say the same about the later years of the Reagan expansion, which was driven at that point by runaway thrift institutions and a large bubble in commercial real estate." But in trying to understand how stagnation itself came about and created this whole irrational set of economic conditions, Krugman…failed to draw attention to the much more important problem of investment under conditions of overcapacity and mature industry, as well as the whole question of monopolistic/oligopolistic capitalism—all of which were taken seriously at some level by Hansen, and were developed in a far more radical way by socialist thinkers such as Michał Kalecki, Joseph Steindl, Paul Baran, and Paul Sweezy.This article can also be found at the Monthly Review website, where most recent articles are published in full.Click here to purchase a PDF version of this article at the Monthly Review website.

Establishment of persistent fission chains in a super prompt critical system

Through using the basic probability theory and establishing the law of finite chains near the prompt criticality, we deduce the formula of relation between the neutrons number and time in the process of persistent chains initiated by a single-pulse neutron source in burst reaction. The formula is validated by the experiments of CFBR-Ⅱ. The formula is the development of Hansen theory model because it can describe not only the developing tendency in the later stages but also the rapid increasing of neutron number in the early stage. Furthermore, according to the relation between the initial time of burst reaction and the intensity of neutron source, we illustrate that the initial time is hardly dependent on the intensity of weak neutron source.

Thermodynamic characterization of poly (caprolactonediol) by inverse gas chromatography

Specific retention volumes, V 0 , were determined for 21 solute probes on poly (caprolactonediol) (PCLD) in the temperature range 323.15–403.15 K by inverse gas chromatography. The retention diagrams drawn between ln V 0 versus 1/T are linear for all the solutes since PCLD with ten repeating units in its chain behaving like a non polymeric material under the conditions applied. The stationary phase with melting temperature ~321 K is in the liquid state in the GC column over the temperature range studied and hence found to be suitable to determine infinite dilution partial molar thermodynamic properties of mixing for solutes on PCLD. The V 0 values have been used to calculate weight fraction activity coefficients Ω∞ and Flory–Huggins interaction parameters, χ 12 ∞ . The average partial molar enthalpy of solution, $$ \overline{\Updelta H}_{1}^{S} , $$ and partial molar enthalpy of mixing, $$ \overline{\Updelta H}_{1}^{\infty } , $$ are calculated using V 0 and Ω∞ respectively. The average molar enthalpy of vaporization ΔH 1 for solutes have been calculated using $$ \overline{\Updelta H}_{1}^{\infty } $$ and $$ \overline{\Updelta H}_{1}^{S} $$ values and compared with the literature values at 363.15 K which is the average column temperature. The partial molar entropy of mixing, $$ \overline{\Updelta S}_{1}^{\infty } $$ calculated at 363.15 K are in good correlation with the average $$ \overline{\Updelta H}_{1}^{\infty } $$ values. The total solubility parameter due to Guillet and the Hansen solubility parameters (HSP) are calculated for PCLD using χ 12 ∞ values. In the present work the Hansen solubility parameters have been calculated using a new method following the Hansen theory and Huang method with less weight on polar and hydrogen bonding components. The errors in the solubility HSP are lower and the correlation coefficients are better in both the methods compared to unweighted three dimensional model.

Evolution of chemical species during electrodeposition of uranium for alpha spectrometry by the Hallstadius method

The morphology and composition of uranium alpha sources with co-deposited platinum have been investigated by scanning electron microscopy (SEM) with energy dispersive X-ray fluorescence analysis (EDX), X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS) studies. Combined SEM and EDX measurements reveal the effect of porous platinum on the morphology of the sources which in turn affects their alpha-spectral resolution. The XPS analysis suggests that the presence of platinum initially increases the concentration of hydroxyl species in the deposits, which then act as centres for subsequent preferential uranium precipitation. XPS and XAFS analysis also provide for first time an indication of oxidation states of uranium present in the sources prepared by the Hallstadius method. These results are in line with Hansen's theory of electrodeposition of actinides.

Heavy Oil Dilution

Heavy crude oils cannot be transported by pipeline without a prior reduction of their viscosity. This is commonly obtained by blending the oil with light hydrocarbons. In that case, the resulting viscosity of the mixture depends only on the dilution rate, on the respective viscosities and densities of the oil, and of the diluent. The addition of a polar solvent to a solution of asphaltenes in toluene acts on the colloidal structure of the asphaltenes. The relative viscosity of the solution decreases. Small-angle X-ray scattering (SAXS) measurements show that the radius of gyration of the aggregates of asphaltenes decreases too. In the same way, by mixing hydrocarbons and solvents owning polar functional groups in their molecule, it is shown that the efficiency of the dilution of heavy crude oils is enhanced. Hansen's theory can be used to screen the solvent efficiency. At constant dilution rate, the higher the polarity parameter or the hydrogen bonding parameter of the solvent, the greater the relative viscosity reduction of the diluted crude oil. Nevertheless, solvent owning high hydrogen bonding are generally more viscous than hydrocarbons. The influence of their interactions with the asphaltenes is hidden when the results are expressed in absolute viscosity. Only polar solvents giving few hydrogen bonding give a significant reduction of the viscosity of the diluted crude oil.