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Abstract Mid-infrared spectra of amorphous and crystalline methyl propionate, CH 3 CH 2 COOCH 3 , are presented for the first time from a single laboratory, along with measurements of the refractive index of each solid form. Density estimates are made and IR band strengths and absorption coefficients are calculated. Vapor pressures of crystalline methyl propionate at 140–150 K are reported along with an enthalpy of sublimation. Spectroscopic results are compared to a recent study of this compound, and the phase of methyl propionate in that work is identified. Several applications are described. Graphical Abstract Unlabelled Image Highlights • Mid-infrared spectra of amorphous and crystalline methyl propionate (CH 3 CH 2 COOCH 3) have been recorded at 10 - 160 K. • IR absorption coefficients and band strengths are reported for the first time for both solid forms of methyl propionate. • Refractive indices at 670 nm are reported for both solid forms of methyl propionate, and used to compute a density for each. • Vapor pressures and an enthalpy of vaporization are reported for crystalline methyl propionate. • Comparisons are made between measured spectral intensities of methyl propionate and calculated values in a recent paper. [ABSTRACT FROM AUTHOR]

Successful development of marketable freeze-dried protein formulations requires adequate stabilization of the active biopharmaceutical ingredient. The choice of a stabilizer must therefore be based on sound knowledge of the physical and chemical properties of the excipients and specific needs of the protein component. Amino acids, such as arginine, have exhibit cryo- and lyoprotective effects similar to those of sugars and polymers and may therefore be considered to be an alternative approach to these established formulation strategies. The chemical structure and physicochemical characteristics of arginine are unique among amino acids and can provide additional benefits to freeze-dried protein formulations with regard to liquid and solid-state stability. This mini review provides a brief summary of research focused on the application of arginine in freeze-dried protein pharmaceuticals, including a discussion of its basic physical and chemical attributes as well as thermal behavior in the frozen and solid states. Mechanisms contributing to solid-state stabilization by arginine are discussed in the context of available stability studies on arginine-containing protein formulations. This mini review seeks to deepen the understanding of the opportunities and challenges associated with arginine-based preparations for freeze-dried protein pharmaceuticals. [ABSTRACT FROM AUTHOR]

Mid-infrared spectra of amorphous and crystalline acetone are presented along with measurements of the refractive index and density for both forms of the compound. Infrared band strengths are reported for the first time for amorphous and crystalline acetone, along with IR optical constants. Vapor pressures and a sublimation enthalpy for crystalline acetone also are reported. Positions of 13 C-labeled acetone are measured. Band strengths are compared to gas-phase values and to the results of a density-functional calculation. A 73% error in previous work is identified and corrected. [ABSTRACT FROM AUTHOR]

We study the shear-induced fluidization of amorphous solids subjected to external loading by investigating the relaxation dynamics of the deformed states using computer simulation. A simple shear deformation is employed at constant rate to the thermal glassy materials. The shear localization and the plastic deformation heterogeneity with strain is investigated in terms of the non-affine displacement field. The mean square displacement shows an enhanced mobility of the particles with strain, indicating the fluidization of the material. Using the time correlation function we estimate the relaxation time of the sheared glasses. A significant decrease in the relaxation time is observed up to the yielding point as the material loses its solid nature and eventually becomes liquid-like. Finally, the imprint of memory of the quiescent sample on the rheological properties of the shear melted glass is investigated by computing the relaxation of the shear stress. We find a finite persistent residual stress that outlasts the experimental observation time in our system. [ABSTRACT FROM AUTHOR]

Mid- and far-infrared spectra of condensed ethanol (CH 3 CH 2 OH) at 10–160 K are presented, with a special focus on amorphous ethanol, the form of greatest astrochemical interest, and with special attention given to changes at 155–160 K. Infrared spectra of amorphous and crystalline forms are shown. The refractive index at 670 nm of amorphous ethanol at 16 K is reported, along with three IR band strengths and a density. A comparison is made to recent work on the isoelectronic compound ethanethiol (CH 3 CH 2 SH), and several astrochemical applications are suggested for future study. [ABSTRACT FROM AUTHOR]

Current popular Monte Carlo simulation codes for simulating electron bombardment in solids focus primarily on electron trajectories, instead of electron-induced displacements. Here we report a Monte Carol simulation code, DEEPER ( d amag e cr e ation and p article transport in matt er ), developed for calculating 3-D distributions of displacements produced by electrons of incident energies up to 900 MeV. Electron elastic scattering is calculated by using full-Mott cross sections for high accuracy, and primary-knock-on-atoms (PKAs)-induced damage cascades are modeled using ZBL potential. We compare and show large differences in 3-D distributions of displacements and electrons in electron-irradiated Fe. The distributions of total displacements are similar to that of PKAs at low electron energies. But they are substantially different for higher energy electrons due to the shifting of PKA energy spectra towards higher energies. The study is important to evaluate electron-induced radiation damage, for the applications using high flux electron beams to intentionally introduce defects and using an electron analysis beam for microstructural characterization of nuclear materials. [ABSTRACT FROM AUTHOR]

• A mean-field shear transformation zone theory is developed for amorphous polymers. • The model is able to fully capture the behaviors of amorphous polymers in various loading conditions. • The Bauschinger effect can be well described by the model, which remains a challenge for other modeling approaches. The complex nonlinear constitutive behavior of amorphous polymers has been extensively investigated in numerous experiments, displaying a strong dependence on the thermal history and loading path. Theoretical models have been proposed to conjoin the underlying mechanisms to certain aspects of mechanical features, such as yielding, strain hardening, physical aging, and the Bauschinger effect. However, an urgent need for theoretical understanding capable of fulfilling the comprehensive predictions of the featured constitutive behaviors of amorphous polymers is to be addressed. In this paper, we develop a micromechanical mean-field shear transformation zone (STZ) model to systematically describe the stress responses of amorphous polymers. The dynamics of STZ is affected by the nonequilibrium structural state described by effective temperature and also related to the anisotropic internal structure induced by the microscopical deformation. Our model exhibits the ability to fully capture the behaviors of amorphous polymers in constant rate/switch rate loading, creep, relaxation, and loading-unloading-reloading cycles. The model is further verified by reproducing the Bauschinger effect in experiments, which remains a challenge to other widely used models. Our results show that the deformation-induced material polarization, in the form of an anisotropic distribution of STZs, is the governing mechanism of the Bauschinger effect. This work establishes a comprehensive relationship between the microscopic mechanisms and the constitutive behaviors of deforming amorphous polymers, which advances the fundamental understanding of complex mechanical behaviors in amorphous glassy polymers. [ABSTRACT FROM AUTHOR]

Quantifying mechanical disorder in solids, either disordered crystals or glassy solids, and understanding its range of variability are of prime importance, e.g. for discovering structure–properties relations. The bounds on the degree of mechanical fluctuations in disordered solids and how those depend on solids formation history remain unknown. Here, we study a broadly applicable quantifier of mesoscopic mechanical disorder χ , defined via the dimensionless fluctuations of the shear modulus, over a wide variety of disordered computer solids and upon varying different control parameters. χ is intimately related to basic properties of disordered solids, such as elastic constants and plastic deformability, and can be experimentally extracted by wave-attenuation measurements. We find that a large variety of self-organized glassy solids, where disorder is an emergent property, appear to satisfy a generic lower bound on χ. On the other hand, we show that χ is unbounded from above, and may diverge in systems driven towards the critical unjamming point. These results highlight basic properties of disordered solids and set the ground for systematically quantifying mechanical disorder across different systems. • We introduce a broadly applicable, dimensionless quantifier of mechanical disorder χ. • χ offers a framework within which disordered solids can be compared on equal footing. • χ is related to basic properties of glassy solids and can be experimentally measured. • χ is studied over a wide range of computer glasses and disordered solids. • It is shown that χ diverges near the so-called 'unjamming' point. [ABSTRACT FROM AUTHOR]

Here we review recent studies of mechanical metamaterials originating from or closely related to marginally jammed solids. Unlike previous approaches mainly focusing on the design of building blocks to form periodic metamaterials, the design and realization of such metamaterials exploit two special aspects of jammed solids, disorder and isostaticity. Due to the disorder, every single bond of jammed solids is unique. Such a bond uniqueness facilitates the flexible adjustment of the global and local elastic responses of unstressed spring networks derived from jammed solids, leading to auxetic materials with negative Poisson's ratio and bionic metamaterials to realize allostery and flow controls. The disorder also causes plastic instabilities of jammed solids under load. The jammed networks are thus inherently metamaterials exhibiting multi-functions such as auxeticity, negative compressibility, and energy absorption. Taking advantage of isostaticity, topological mechanical metamaterials analogous to electronic materials such as topological insulators have also been realized, while jammed networks inherently occupy such topological features. The presence of disorder greatly challenges our understanding of jammed solids, but it also provides us with more freedoms and opportunities to design mechanical metamaterials. [ABSTRACT FROM AUTHOR]

[Display omitted] Mesoscale elasto-plastic models, with statistically distributed structural properties and elastic coupling between discrete blocks, have been shown to quantitatively reproduce the main phenomenology observed in the stationary flow state of glasses as modelled at the atomic scale [1]. In the present study, an extension of such approaches is proposed to describe the transient mechanical response of glasses from different off-equilibrium states in the athermal quasi-static limit. Equilibrated liquids are simulated using two-dimensional molecular dynamics, quenched instantaneously to zero temperature, and then sheared. The mechanical observables measured in atomistic and elasto-plastic models are compared at the same length scales to calibrate a state-dependent constitutive law. A physical mechanism is proposed where the structural properties' evolution rate depends on the magnitude of local plastic deformation events, introducing an effective local memory of previous states in the system. This mechanism naturally leads to a brittle-ductile transition in the mechanical response of glasses, which depends exclusively on the quenched structure. Specifically, initially stable glasses exhibit strain-softening and localization, where the memory of the initial states is lost abruptly after the first plastic rearrangements. On the other hand, systems quenched from high-temperature liquids show a slow strain-hardening with statistically homogeneous plastic deformation. In these initially soft glasses, numerous plastic rearrangements are required to converge toward the stationary flow state. The elasto-plastic model successfully reproduces the stress-strain curves in the transient regime for the whole range of parent temperatures by including this local memory mechanism. The limitations of the model are finally discussed, together with possible improvements. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate product performance of freeze dried l-arginine/sucrose-based formulations under variation of excipient weight ratios, l-arginine counter ions and formulation pH as a matrix to stabilize a therapeutic monoclonal antibody ( MAb) during freeze drying and shelf life. Protein and placebo formulations were lyophilized at aggressive primary drying conditions and key attributes of the freeze dried solids were correlated to their thermal properties and critical formulation temperature. Stability (physical) during processing and long-term storage of the MAb in different formulations was assessed by SE- HPLC. Thermal properties of the mixtures were greatly affected by the type of l-arginine counter ion. High glass transition temperatures were achieved by adding multivalent acids, whereas the temperature values significantly decreased in the presence of chloride ions. All mixtures were stable during freeze drying, but storage stability varied for the different preparations and counter ions. For l-arginine-based formulations, the protein was most stable in the presence of chloride ion, showing no obvious correlation to estimated global mobility of the glass. Besides drying behavior and thermal properties of the freeze dried solids, the counter ion of l-arginine must be considered relevant for protein shelf life stability. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 104:2345-2358, 2015 [ABSTRACT FROM AUTHOR]

A series of Zr-Al-Ni-Cu bulk metallic glasses (BMGs) with network structures were carefully designed and their heterogeneous microstructures were investigated by carefully etching the cross sections of these BMGs. It is found that the heterogeneous microstructures of these BMGs can be uncovered by etching with mixed solution of HF and HNO3. Some of the studied Zr-based BMGs characterize in micrometer network structure. The cell size of the network structure depends on the composition of the BMG and is related with the fractural mode and mechanical property. The found network structure of the Zr-based BMGs benefits for understanding the unique mechanical properties of the Zr-based BMGs. [ABSTRACT FROM AUTHOR]

Understanding the fundamentals of alkali diffusion in boroaluminosilicate glasses is of critical importance for advanced glass applications, where the alkali diffusivity should be either enhanced or reduced. Here, we investigate the sodium-potassium interdiffusivity in thirty-six alkaline earth sodium boroaluminosilicate glasses with varying Si/Al ratio and type of alkaline earth cation by ion exchange experiments. The alkali mobility is maximized when Na+ acts as a charge compensator to Al3+ or B3+ in the glass rather than as a creator of non-bridging oxygen. In the peralkaline regime, the larger alkaline earth cations significantly slow down the motion of alkali ions, while this effect is much smaller in the peraluminous regime. Generally, there is a larger effect of increasing temperature on diffusivity for the larger alkaline earth cations than for the smaller ones. [ABSTRACT FROM AUTHOR]

Abstract: “Microalloying”, which refers to the addition of small concentrations of a foreign metal to a given metallic glass, has been used extensively in recent years in attempts to improve the mechanical properties of these glasses. The results are haphazard and nonsystematic. In this paper we provide a microscopic theory of the effect of microalloying, exposing the delicate consequences of this procedure and the large parameter space which needs to be controlled. In particular we consider two very similar models which exhibit opposite trends for the change of the shear modulus, and explain the origins of this difference as displayed in the various microscopic structures and properties. [Copyright &y& Elsevier]

Highlights: [•] 14N nuclear quadrupole resonance in amorphous phase. [•] Separation of NQDR signals from amorphous and crystalline parts of an inhomogeneous sample. [•] Separation of NQDR signals from various crystal polymorphs in an inhomogeneous sample. [•] Determination of mass fraction of a crystalline part in an inhomogeneous sample from NQDR line intensity. [ABSTRACT FROM AUTHOR]

Abstract: A new dilatometry method has been developed for studying small cylindrical powder compacts based on non-contact white light interferometry which offers a z resolution of <10nm. In-situ compact dimensions were measured as a function of time with controlled relative humidity and temperature, allowing the study of recrystallization and other volumetric changes for amorphous lactose compacts. Complementary X-ray powder diffraction and dynamic vapor sorption data confirmed both water sorption and recrystallization kinetics. At 35% RH the compacts exhibited 0.6% height expansion consistent with vapor sorption in a glassy material. For 55% RH and 75% RH, small initial shrinkages (~2.5%) associated with the moisture induced plasticization of the lactose particles and their relaxation or collapse were observed, followed by a significant height expansion (~15%) of the compacts due to swelling of the rubbery lactose phase prior to crystallization. The kinetics at 55% and 75% RH indicated a smooth dimensional transition from water swollen to crystalline lactose compacts. A detailed surface area study by N2 BET adsorption of a range of compacts showed no statistically significant surface area changes above or below the Tg. [Copyright &y& Elsevier]

Abstract: All-solid-state lithium batteries were fabricated by use of LiNi1/3Mn1/3Co1/3O2 powders coated with ZrO2 as positive electrode materials and amorphous Li3PS4 as solid electrolytes. The ZrO2-coated powders were prepared by a sol–gel method associated with ultrasonic irradiation. The charge–discharge cycle performance of the all-solid-state cells was improved by use of the ZrO2-coated LiNi1/3Mn1/3Co1/3O2 powders. The ZrO2 coating was effective in suppressing an increasing of the interfacial resistance between the LiNi1/3Mn1/3Co1/3O2 electrode material and the sulfide based solid electrolyte, a-Li3PS4, during charge–discharge cycling. The battery with the ZrO2-coated LiNi1/3Mn1/3Co1/3O2 showed an initial discharge capacity of 115mAhg−1 and good capacity retention even after 50cycles at a current density of 0.1mAcm−2 at room temperature. [Copyright &y& Elsevier]

The succinimide intermediate generated during deamidation of asparagine-containing peptides and proteins has been implicated as having a role in the formation of multiple types of degradants in addition to hydrolysis products, including racemization products and, more recently, amide-linked, nonreducible protein and peptide aggregates. The formation of alternative degradants may be particularly important in solid-state formulations. This study quantitatively examines the role of the succinimide intermediate in hydrolysis, racemization, and covalent, amide-linked adduct formation in amorphous lyophiles. The degradation of a model peptide, Gly-Phe- l-Asn-Gly, and its l- or d-succinimide intermediates were examined in lyophiles containing hydroxypropyl methylcellulose and varying amounts of excess Gly-Val. Disappearance of the starting reactants and formation of up to 10 degradants were monitored when lyophiles were exposed to either 27°C/40% relative humidity (RH) or 40°C/75 RH using a stability indicating high-performance liquid chromatography method. Terminal degradant profiles were the same when the starting reactant was either Gly-Phe- l-Asn-Gly or its succinimide intermediate. Nucleophilic attack occurred preferentially at the α-carbonyl of the succinimide intermediate at ratios of approximately 2:1 for both water and the N-terminus of Gly-Val as the attacking nucleophiles. A mechanism-based kinetic model analysis indicates that hydrolysis, racemization, and covalent, amide-linked adduct formation all proceed via the succinimide intermediate. © 2012 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 101:3096-3109, 2012 [ABSTRACT FROM AUTHOR]

Abstract: Glasses are known to exhibit quantitative universalities at low temperatures, the most striking of which is the ultrasonic attenuation coefficient Q −1. In this work we develop a theory of coupled generic blocks with a certain randomness property to show that universality emerges essentially due to the interactions between elastic blocks, regardless of their microscopic nature. [Copyright &y& Elsevier]

Abstract: Despite recent advances in solid-state NMR spectroscopy, the structural characterization of amorphous active pharmaceutical ingredients (APIs) in solid dosage forms continues to be a monumental challenge. To circumvent complications following from low concentrations of APIs in tablet formulations, we propose a new time-saving procedure based on chemometric approach: factor analysis of 19F MAS NMR spectra. Capability of the proposed method is demonstrated on atorvastatin – a typical representative of fluorinated pharmaceutical substances exhibiting extensive polymorphism. Applying the factor analysis on the recorded 19F MAS NMR spectra, unique parameters for every sample were derived. In this way every solid form of atorvastatin was characterized and clearly distinguishable even among various amorphous and disordered forms. The proposed method was also found to be suitable for both qualitative and quantitative analysis of mixtures of various forms of atorvastatin. Reliability of the proposed method was extensively examined by comparing the obtained results with other experimental techniques such as 13C CP/MAS NMR, FTIR and XRPD. As highly linear correlations between the sets of parameters obtained from different experimental data were found, the perspectives of the applied comparative factor analysis to obtain detail structural view on variability of amorphous forms of atorvastatin are also discussed. Although the reported method was tested on atorvastatin, authors expect wider application for any fluorinated compound to give the routine, fast and reliable characterization of amorphous forms of APIs in drug products even at low concentrations (1–5%). Bear in mind that 20–25% of currently developed pharmaceuticals contain at least one fluorine atom in the molecule. [Copyright &y& Elsevier]

Abstract: Woelk and Strey recently criticized the temperature dependency of nucleation rates of the isothermal Classical Nucleation Theory, of water in its vapor, and showed that the apparent excellent agreement of the theory with experimental data, in a narrow temperature range, is in fact a “crossover” of the theory with experimental data. Similarly, Zanotto and Fokin criticized the isothermal Classical Nucleation Theory for nucleation (devitrification) in silicate glasses, claiming that “the theory fails to describe nucleation rates in glasses quantitatively.” Finally, Schmelzer, Boltachev and Baidakov stated that: “…deviations between theoretical and experimental data for the steady-state nucleation rate may reach the order of 1020–1030 for condensation of one component vapors and even 10100 or more for phase formation in glass-forming melts.” This situation shows the need for new proposals to explain the phenomenon. We demonstrate that a simple Adiabatic Nucleation Theory predicts nucleation rates in “fragile” oxide glasses (T 00/T g >0.6, where T 00 is the Fulcher temperature and T g is the glass transition temperature) with an average deviation of only nine orders of magnitude (too high) and shows (within this uncertainty) correctly which glasses show devitrification and which ones do not, in experiments during “laboratory times.” The theory could not yet be extended to “strong” glasses because of the very low Fulcher temperatures of these glasses (T 00/T g <0.6), in which the Stokes-Einstein relation loses its validity completely. [ABSTRACT FROM AUTHOR]

Abstract: In this contribution we present an in-depth study of the network structure of different phosphate based and borosilicate glasses and its evolution at high temperatures. Employing a range of advanced solid state NMR methodologies, complemented by the results of XPS, the structural motifs on short and intermediate length scales are identified. For the phosphate based glasses, at temperatures above the glass transition temperature T g, structural relaxation processes and the devitrification of the glasses were monitored in situ employing MAS NMR spectroscopy and X-ray diffraction. Dynamic species exchange involving rapid P–O–P and P–O–Al bond breaking and reforming was observed employing in situ 27Al and 31P MAS NMR spectroscopy and could be linked to viscous flow. For the borosilicate glasses, an atomic scale investigation of the phase separation processes was possible in a combined effort of ex situ NMR studies on glass samples with different thermal histories and in situ NMR studies using high temperature MAS NMR spectroscopy including 11B MAS, 29Si MAS and in situ 29Si{11B} REAPDOR NMR spectroscopy. [Copyright &y& Elsevier]

Abstract: The chemico–physical properties, near infrared and TG-DTA behavior of the non-crystalline silica prepared by water glass with different initial concentrations were systematically investigated. The structural parameters obtained by X-ray diffraction technique showed that the short range order was no more than 5–6 atoms. The variations of calculated co-ordination number and Si–O bond length, which to some extent reflected the structural compactness, explained the variation of the measured oil absorption well. [Copyright &y& Elsevier]

Abstract: Viscoelastic behaviour of a metallic glass Zr55Al10Ni5Cu30 has been studied by measuring the dynamic shear modulus G under forced vibration at low frequencies below 1Hz. In measurements with increasing temperature, the shear modulus falls markedly at temperatures around the glass transition but at different rates under different vibration frequencies. The dynamic viscosity η has been evaluated using the relation η = G/(iω), where ω is the angular frequency. The curves of |η| vs temperature of different frequencies converge to a single curve in the glass transition region, and the converged curve is in fair agreement with the data reported in the literature. The dynamic glass transition point, defined as the vibration frequency and temperature at which the curves of the storage modulus G 1 and the loss modulus G 2 cross each other, obeys the Arrhenius law. The pre-exponential factor and the activation energy of the transition frequency are unusually large, suggesting that collective movements of atoms control the transition. [Copyright &y& Elsevier]

• Europium trioxide doped lead boro tellurite glasses were prepared by the conventional melting quenching technique. • The non-crystalline nature of the glasses was confirmed by XRD measurements. • The electrical transport mechanism was well fitted with the Almond-West type of power law. • With increasing temperatures, s (exponential) values have been found to decrease. • The stretched exponent β values were found to be insensitive to the change in temperature. A very rare set of glasses having chemical compositions of B 2 O 3 -TeO 2 -Na 2 O-PbO, doped with europium trioxide were obtained by the conventional melt quenching procedure. An X-ray diffractometer was run to confirm the non-crystalline nature of the structural studies. The AC conductivity and dielectric properties of glasses were studied in the temperature range 343–483 K with a 40 Hz to 6 MHz frequency range. The Almond–West model of power-law suggests, the well-fitting of found AC conductivity values and conductivity is due to translational motions of carriers. AC conductivity decreases with increasing concentration of Eu 2 O 3. The non-Debye type of relaxations was predicted by AC conductivity plots. The dielectric constant and dielectric loss of complex permittivity was measured and obtained values suggested that the phenomenon of dielectric relaxation is mainly subjected to the frequency-dependent polarization mechanism. The obtained power-law exponent values indicate the AC conductivity mechanism and follow the CBH model. [ABSTRACT FROM AUTHOR]

• Cryostat for thermal conductivity measurement. • Material in amorphous or polycrystalline state can be obtained inside the cryostat. • Sample is heated to the melting point and then cooled to the glass transition temperature. • The average cooling rate is about 22 K/min. Experimental setup for the thermal conductivity measurement of amorphous solids with the glass transition temperature below 250 K is presented. This setup allows to heat the specimen to the melting point and then cool it fast to the glass transition temperature. Thermal conductivity can be investigated in the temperature range from 5 K to 300 K. Thermal conductivity of ethanol in amorphous and polycrystalline states was measured for the verification of the setup function. The results of the measurements agree well with those presented in literature. [ABSTRACT FROM AUTHOR]

The bimolecular reaction between cysteine (CSH) and hydrogen peroxide (H2O2) in amorphous PVP and trehalose lyophiles has been examined at different reactant and excipient concentrations and at varying pH and temperature. Initial rates of product formation and complete reactant and product concentration-time profiles were generated by HPLC analyses of reconstituted solutions of lyophiles stored for various periods of time. While only cystine (CSSC) forms in aqueous solutions, cysteine sulfinic (CSO2H) and sulfonic (CSO3H) acids are significant degradants in amorphous solids. The formation of alternative degradants was consistent with the solution reaction mechanism, which involves a reactive sulfenic acid (CSOH) intermediate, coupled with the restricted mobility in the amorphous solid-state, which favors reaction of CSOH with the smaller, mobility-advantaged H2O2 over its reaction with cysteine. Complex rate laws (i.e., deviations from 1st order for each reactant) observed in initial rate studies and biphasic concentration-time profiles in PVP were successfully fitted by a two-state kinetic model assuming two reactant populations with different reactivities. The highly reactive population forms CSSC preferentially while the less reactive population generates primarily sulfinic and sulfonic acids. Reactions in trehalose could be described by a simple one-state model. In contrast to the reaction in aqueous solutions, the ‘pH’ effect was minimal in amorphous solids, suggesting a change in the rate-determining step to diffusion control for the model reaction occurring in amorphous lyophiles. © 2008 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97:3907–3926, 2008 [ABSTRACT FROM AUTHOR]

Abstract: The paper summarized the recent results in vibrational dynamics of disordered solids obtained in joint research of Bayreuth University and Institute of Spectroscopy RAS groups via single molecule spectroscopy (SMS). New information about microscopic parameters of the low-frequency vibrational modes (LFMs) in low-temperature glasses was obtained. Studies were based on observations of the line-broadening processes in spectra of single chromophore molecules (SMs) incorporated to disordered matrix as a local spectral probe. Solid organic system, amorphous polymer—polyisobutylene, doped with tetra-tert-butylterrylene molecules, on temperature region 1.6–40K have been studied. The values of LFM frequencies and SM-LFM coupling constants for the LFMs in the local environment of dopand chromophores were determined. Pronounced distributions of the observed local parameters of LFMs were found. The obtained results demonstrate that SMS is an efficient tool in the study of vibrational dynamics in solid disordered systems on microscopic level. [Copyright &y& Elsevier]

Abstract: We consider a hydrogel in the framework of a continuum theory for the viscoelastic deformation of amorphous solids developed by Anand and Gurtin [Anand, L., Gurtin, M., 2003. A theory of amorphous solids undergoing large deformations, with application to polymeric glasses. International Journal of Solids and Structures, 40, 1465–1487.] and based on (i) a system of microforces consistent with a microforce balance, (ii) a mechanical version of the second law of thermodynamics and (iii) a constitutive theory that allows the free energy to depend on inelastic strain and the microstress to depend on inelastic strain rate. We adopt a particular (neo-Hookean) form for the free energy and restrict kinematics to one dimension, yielding a classical problem of expansion of a thick-walled cylinder. Considering both Dirichlet and Neumann boundary conditions, we arrive at stress relaxation and creep problems, respectively, which we consider, in turn, locally, at a point, and globally, over the interval. We implement the resulting equations in a finite element code, show analytical and/or numerical solutions to some representative problems, and obtain viscoelastic response, in qualitative agreement with experiment. [Copyright &y& Elsevier]

Abstract: Applications of thermally stimulated depolarisation current (TSDC) technique to a variety of systems with different dispersion phases such as disperse and porous metal oxides, polymers, liquid crystals, amorphous and crystalline solids, composites, solid solutions, biomacromolecules, cells, tissues, etc. in gaseous or liquid dispersion media are analysed. The effects of dipolar, direct current (dc) and space charge relaxations are linked to the temperature dependent mobility of molecules, their fragments, protons, anions, and electrons and depend on thermal treatment, temperature and field intensity of polarisation, heating rate on depolarisation or cooling rate on polarisation. Features of the relaxation mechanisms are affected not only by the mentioned factors but also by morphological, structural and chemical characteristics of materials. The interfacial phenomena, especially the role of interfacial water, received significant attention on analysis of the TSDC data. Comparison of the data of TSDC and dielectric relaxation spectroscopy (DRS), differential scanning calorimetry (DSC), 1H NMR spectroscopy with layer-by-layer freezing-out of bulk and interfacial water, adsorption/desorption of nitrogen, water and dissolved organics demonstrates high sensitivity and information content of the TSDC technique, allowing a deeper understanding of interfacial phenomena. [Copyright &y& Elsevier]

Abstract: The elastic and viscoelastic behavior of a bulk metallic glass Zr55Al10Ni5Cu30 (in mol%) has been studied by isothermal forced-vibration measurements of the dynamic shear modulus. At temperatures of the calorimetric glass transition, on decreasing the frequency from 10+1 to 10−3 Hz at a constant temperature, the storage modulus exhibits a striking drop, of an order of magnitude, which is similar to the change observed under continuous heating. The lowering of the storage modulus and the accompanying maximum in the loss modulus indicate a dynamic glass transition; the material behaves as a solid at high frequencies but as a liquid at low frequencies. The range of frequencies where the storage and loss moduli exhibit the characteristic behavior is much wider than expected from a simple Maxwell model of viscoelasticity. A parallel combination of Maxwell units is found to reproduce the observed trend, and is used to evaluate the characteristic rate constant. Its activation energy and the pre-exponential factor turn out to be anomalously high, indicating that the dynamic glass transition is controlled by collective movements of atoms. [Copyright &y& Elsevier]

Molecular dynamics simulations indicate that the mechanical properties of a model metallic glass depend critically on the degree of supercooling attained in the liquid prior to vitrification. A well-characterized binary glass-forming system roughly analogous to ZrTi was quenched instantaneously from a series of liquid temperatures. These temperatures ranged from approximately twice that of the onset of supercooled liquid behaviour down to just above the mode-coupling temperature (TMCT). The low-temperature mechanical properties of these glass samples is studied in simple shear at constant strain rate while the density of the system is held constant. All the glasses exhibit an initial linear response at small strain and approached a steady-state flow regime at large strain. However, glasses obtained by quenching from supercooled liquids just above TMCT, which we will refer to as TMCT glasses, exhibit higher shear strength and modulus than glasses obtained by quenching from higher temperature liquids. The TMCT glasses also exhibit pronounced shear softening. The change in pressure during shear is markedly different in these glasses, and indicates that the TMCT glasses retain aspects of the quenched-in structure out to as much as 25% strain. The changes in pressure also indicate significant structural changes occur even during nearly linear stress–strain response. [Copyright &y& Elsevier]

Spectra of single tetra-tert-butylterrylene molecules incorporated in purely amorphous polyisobutylene matrix have been measured at 2, 4.5 and 7 K (244, 381 and 187 molecules, correspondingly). This is a temperature region, where the main assumptions of the standard two-level system (TLS) model of low-temperature glasses begin to be not valid. At T=2 K the main parameters of most of the registered spectra were found to be consistent with the standard TLS model. At T=4.5 and 7 K some deviations from predictions of this model were observed. The detailed analysis reveals that increasing of temperature leads to additional, in comparison with the predictions of the standard TLS model, line broadening of spectral peaks. This additional line broadening was attributed to the influence of quasi-local low-frequency modes (LFMs) of the amorphous matrix in system under study at T=4.5 and 7 K.Distributions of single spectral peak widths of the detected spectra (the line width distributions) have been calculated and compared with the line width distributions simulated for the same system. Comparative analysis of experimental and simulated distributions allows to evaluate the value of LFM contribution at 4.5 and 7 K. The single molecule spectroscopy data were compared with the literature values of inverse optical dephasing times, 1/πT2, as measured for the same system by photon echo (S.J. Zilker et al., J. Chem. Phys. 109 (1998) 6780). [Copyright &y& Elsevier]

A novel fitting method implemented recently in vibrational spectroscopy of disordered systems is briefly overviewed. It enables modelling of real line profiles intermediate between Lorentzian and Gaussian by an analytical function which has an analytical counterpart in the time domain. Numerous applications of this theoretical approach are discussed. [Copyright &y& Elsevier]

Al3+ stabilized tetragonal (t)-ZrO2 of nanoparticles is studied with X-ray photoelectron spectroscopy (XPS) as a function of the Al3+ concentration. The samples, with 2–15 mol% Al3+ additives, are prepared by co-hydrolysis of the two types of the metal cations in an amorphous precursor of oxyhydroxyl Zr1−2xAl2xO(OH)2−2x·αH2O gel. Substantially stabile t-ZrO2 occurs with the Al3+ additives on a reconstructive thermal decomposition of gel by heating at 500 °C in air. The Al3+ additive inhibits average t-ZrO2 crystallite size to be as small as 6–8 nm (9 nm otherwise in virgin t-ZrO2) depending on the Al3+ concentration. As analyzed with X-ray diffraction, no independent Al2O3 crystallizes, confirming formation of a perfect Al3+:ZrO2 solid solution under these conditions. Six distinct XPS bandgroups lie, in the 0–600 eV range of the binding energy, in excitations of 2p, 2s, 4p, 3d, or 3p core electrons in Al3+ and Zr4+ cations and in 1s excitation in O2− anions in Al3+:t-ZrO2 solid solution. Weak satellite 3d5/2 and 3d3/2 bands occur at lowered energies (8–10 eV) of the main bands in trace of part of the metal cations present in the lower Zrq+, q≤3, oxidation states. [Copyright &y& Elsevier]

Methodology has been developed to separate nano-particles of amorphous material from Syncrude fine tailings. Both, separated finer solids and residual coarser solids, were characterized by elemental analysis, X-ray powder diffraction, XPS, SEM, infrared spectroscopy, solid-state NMR, density, and surface area measurements. Based on the results of infrared and X-ray diffraction, the amorphous minerals identified in finer solids included allophanes, halloysite, ferrihydrite, and amorphous silica. The finer fraction also contained some crystalline material consisting of muscovite and traces of quartz. The residual coarser solids consisted mostly of quartz, muscovite, and kaolinite. [Copyright &y& Elsevier]

In this paper we present a quantitative model of local viscous flow of amorphous solid during the cooling down of a swift heavy ion track, taking into account both the heat dissipation by heat conduction and the temperature dependence of material viscosity. [Copyright &y& Elsevier]

Extended X-ray absorption fine structure measurements have been used to characterize, at the atomic level, the thermally induced structural relaxation of InAs amorphized by ion implantation. Our results are consistent with a relaxation mechanism mediated by point-defect annihilation with concomitant reduction in both chemical and structural disorder. Though relaxation yields a decrease in chemical disorder, homopolar bonding is still retained in the fully relaxed amorphous structure. [Copyright &y& Elsevier]

In this paper, a new dispersion model of the optical constants of amorphous solids enabling us to perform an efficient parameterization of the spectral dependences of the optical constants of chalcogenide thin films will be presented. This dispersion model is based on mathematical modeling the density of electronic states (DOS) corresponding to both the valence and conduction bands. The imaginary part of the dielectric function is then calculated by the numerical convolution of the DOS. The real part of the dielectric function is calculated using the corresponding Kramers–Kronig (KK) relation in a suitable numerical way. Moreover, the existence of the transitions between the localized states inside the band gap and the extended states inside both the valence and conduction bands is also taken into account using the corresponding convolutions. Thus, the dispersion model presented includes the absorption corresponding to the Urbach and Tauc regions. Then the dispersion model described allows to interpret spectroellipsometric and spectrophotometric data measured for the chalcogenide thin films within the wide spectral region (200–900 nm). [Copyright &y& Elsevier]

A mixed aqueous solution (0.2–0.5 M) of ZrOCl2·8H2O and AlCl3·6H2O has a controlled forced hydrolysis to form an amorphous Zr1−2xAl2xO(OH)2−2x·αH2O precursor on adding NH4OH (in water) dropwise in a controlled manner at room temperature or preferably lower. X-ray diffraction of four halos at 19.2, 28.5, 39.2, and 57.0 nm−1 wavevectors (x=0.05) characterizes the amorphous structure of the precursor. It undergoes a self-controlled reconstructive thermal decomposition into stabilized c-ZrO2 of nanoparticles in Fm3m cubic crystal structure at temperature as low as 200 °C. The process involves a predominant endothermic signal with a total of ∼60% loss in the precursor mass. It controls the local temperature and in turn governs moderate nucleation and grain growth in nanocrystals. The x=0.02–0.10 Al3+additives cultivate stabilized c-ZrO2 crystallites in 6–12 nm confined size (d) on heating the precursor at 200–800 °C for 2–5 h. A reconstructive c→t/m-ZrO2 phase transformation appears at extended temperature as 1000 °C as per the Al3+additives. A pure m-phase, d∼26 nm, results at 1200 °C (800 °C otherwise at x=0). The lattice parameters vary as the x-value. The results of c-ZrO2 formation and its stability and phase transformation are studied with X-ray diffraction, microstructure and thermal analysis of representative specimens. [Copyright &y& Elsevier]

This paper develops a continuum theory for the elastic–viscoplastic deformation of amorphous solids such as polymeric and metallic glasses. Introducing an internal-state variable that represents the local free-volume associated with certain metastable states, we are able to capture the highly non-linear stress–strain behavior that precedes the yield-peak and gives rise to post-yield strain softening. Our theory explicitly accounts for the dependence of the Helmholtz free energy on the plastic deformation in a thermodynamically consistent manner. This dependence leads directly to a backstress in the underlying flow rule, and allows us to model the rapid strain-hardening response after the initial yield-drop in monotonic deformations, as well as the Bauschinger-type reverse-yielding phenomena typically observed in amorphous polymeric solids upon unloading after large plastic deformations. We have implemented a special set of constitutive equations resulting from the general theory in a finite-element computer program. Using this finite-element program, we apply the specialized equations to model the large-deformation response of the amorphous polymeric solid polycarbonate, at ambient temperature and pressure. We show numerical results to some representative problems, and compare them against corresponding results from physical experiments. [Copyright &y& Elsevier]

This paper describes the kinetics of the solution-mediated phase transformation of the anhydrous monoclinic polymorph of carbamazepine (CBZ(A)) to the dihydrate crystal form (CBZ(D)). Monitoring both solution concentration and solid phase composition identified the steps and mechanisms that control the kinetic processes, and regulate the concentration of drug achieved during dissolution of the metastable solid phase, CBZ(A). The results show that the kinetics and the rate-controlling step for the transformation depend on grinding and storage conditions of CBZ(A). Grinding CBZ(A) shortened the transformation times and changed the rate-controlling step from crystallization of CBZ(D) to dissolution of CBZ(A). Grinding may cause various degrees of disorder in the form of lattice defects and/or amorphous regions. These disordered regions promote the anhydrous to dihydrate transformation by facilitating the surface nucleation of CBZ(D) on freshly ground CBZ(A) and on amorphous CBZ. The concentration-time profiles revealed aging effects on the solution-mediated transformation of ground CBZ(A) that were undetectable by diffraction and thermal analysis. These results have significant consequences on the concentration-time profiles of active pharmaceutical ingredients during dissolution of metastable solid phases, crystalline or amorphous. [Copyright &y& Elsevier]

The approach for description of the optical dephasing in doped amorphous solids in the framework of the soft-potential model (SPM) was developed. A procedure for calculation of the homogeneous line width at low temperatures within this model was suggested. The temperature dependencies of the optical dephasing for two amorphous systems, polymethimetacrylate doped with tetra-tert-butylterrylene and zinc-tetraphenylporphine were calculated. Calculations were performed using the parameters known from the literature. The results were compared with the photon echo data for these systems, measured in the broad temperature range. It was found that the SPM describes the temperature behavior of the homogenous line width qualitatively correctly. At temperatures below 2 K, where the main contribution to optical dephasing is associated with tunneling two-level systems, the predicted line width values agree well with the experimental data. At higher temperatures, some difference between the prediction and experimental data was observed and attributed to the effect of impurity on the formation of quasilocal oscillations of the matrix. [Copyright &y& Elsevier]

We investigated the possible effect of the existence of minimal cutoff distance between two-level system (TLS) and chromophore molecule in glasses on the low-temperature photon echo (PE) and single molecule spectroscopy (SMS) data. Our analysis was based on the tunneling TLS and sudden jump models of glasses. The PE data were considered using the stochastic model of PE in low-temperature glasses as modified by us. Analysis of SMS data was based on the theory of SM line shapes developed by Geva and Skinner [J. Phys. Chem. 101 (1997) 8920]. It was shown that the existence of a minimal approach distance between TLS and chromophore centers results in noticeable changes of the calculated PE and SMS data. These changes increase with increasing of temperature. [Copyright &y& Elsevier]

Extended X-ray absorption fine structure measurements have been utilized to determine the structural parameters of InAs amorphised by ion implantation. Relative to crystalline standards, increases in bond length and Debye–Waller factor were apparent. Our results indicate that a total coordination number of four atoms, as observed in the crystalline phase, is retained in the amorphous material. Furthermore, homopolar bonding, forbidden in the crystalline phase, is present in the amorphous material and, apparently, in amorphous III–V semiconductors in general. [Copyright &y& Elsevier]

• Hamiltonian of interacting spins calculated by the Handrich-Kobe approximation. • Amorphous systems with ferrimagnetism and high caloric potentials. • Magnetism, direct and inverse magnetocaloric effect, and magnetic refrigeration. In this work we will investigate the magnetic and magnetocaloric properties in the amorphous alloys formed by the Gd 55 Fe x Al 45 − x series. From an experimental point of view, it has been reported that these systems have high values for refrigerant capacity, and interesting magnetocaloric properties associated with the ferrimagnetic order. We propose a theoretical model described by two coupled magnetic sublattices of localized spins in the presence of an applied magnetic field based on Handrich's approximation to study these systems. Through this model, we calculate the magnetization and the isothermal entropy change as functions of the temperature under the applied magnetic field change. We will try to understand the role of substitution of Fe for Al in the characterization of magnetism and the magnetocaloric effect of these systems. In addition, the study is important to understand the physical mechanisms involved in the ferrimagnetic transitions of amorphous alloys. [ABSTRACT FROM AUTHOR]

Chalcogenide phase-change materials (PCMs) are regarded as the leading candidate for storage-class non-volatile memory and neuro-inspired computing. Recently, using the TiTe 2 /Sb 2 Te 3 material combination, a new framework – phase-change heterostructure (PCH), has been developed and proved to effectively suppress the noise and drift in electrical resistance upon memory programming, largely reducing the inter-device variability. However, the atomic-scale structural and chemical nature of PCH remains to be fully understood. In this work, we carry out thorough ab initio simulations to assess the bonding characteristics of the PCH. We show that the TiTe 2 crystalline nanolayers do not chemically interact with the surrounding Sb 2 Te 3 , and are stabilized by strong covalent and electrostatic Ti–Te interactions, which create a prohibitively high barrier for atomic migration along the pulsing direction. We also find significant contrast in computed dielectric functions in the PCH, suggesting possible optical applications of this class of devices. With the more confined space and therefore constrained phase transition compared to traditional PCM devices, the recently introduced class of PCH-based devices may lead to improvements in phase-change photonic and optoelectronic applications with much lower stochasticity during programming. [ABSTRACT FROM AUTHOR]

In the last few decades, theoretical and experimental studies of glass-forming liquids have revealed presence of universal regularities in the viscosity-temperature data. In the present work, we propose a viscosity model for scaling description of experimental viscosity data. A feature of this model is presence of only two adjustable parameters and high accuracy of experimental data approximation by this model for a wide temperature range. The basis of the scaling description is an original temperature scale. Within this scaling description we obtain the transformed Angell plot, in which the area separating "fragile" and "strong" glass-formers emerges. The proposed scaling procedure make it possible to reconsider belonging some liquids to the type of "fragile" glass-formers. The obtained results form basis for development of a generalized scaling description of crystallization kinetics in supercooled liquids and glasses. [ABSTRACT FROM AUTHOR]