Search

The requirement for temperature‐controlled storage can be challenging and expensive for the transportation and storage of biologics. Light‐assisted drying (LAD) is a new processing technique to prepare biologics for storage in a trehalose amorphous solid matrix at ambient temperatures. Samples are illuminated with near‐infrared laser light to speed dehydration. Previous work has shown LAD can prepare small‐volume (40 μL) samples, but the feasibility of applying LAD to larger samples remains unexplored. Here, LAD is applied to large‐volume samples (250 μL). Samples of a trehalose solution with an embedded protein were LAD processed and stored for 1 month. The end moisture contents of samples were determined after processing and storage. Thermal histories were monitored to determine optimal drying times. The trehalose matrix was characterized using polarized light imaging and Raman spectroscopy. Karl‐Fischer (KF) titration was used to measure the water content. The end moisture contents and thermal histories show high repeatability for LAD processing. Polarized light imaging demonstrates that the trehalose matrix was resistant to crystallization. Raman spectroscopy indicates uniform water distribution and KF titration reveals a low average water content (2.5%). LAD can stabilize large‐volume samples for dry‐state storage at ambient temperatures and offers a potential solution for cold‐chain storage challenges. [ABSTRACT FROM AUTHOR]

Mechanical stress governs the dynamics of viscoelastic polymer systems and supercooled glass-forming fluids. It was recently established that liquids with long terminal relaxation times are characterized by transiently frozen stress fields, which, moreover, exhibit long-range correlations contributing to the dynamically heterogeneous nature of such systems. Recent studies show that stress correlations and relaxation elastic moduli are intimately related in isotropic viscoelastic systems. However, the origin of these relations (involving spatially resolved material relaxation functions) is non-trivial: some relations are based on the fluctuation-dissipation theorem (FDT), while others involve approximations. Generalizing our recent results on 2D systems, we here rigorously derive three exact FDT relations (already established in our recent investigations and, partially, in classical studies) between spatio-temporal stress correlations and generalized relaxation moduli, and a couple of new exact relations. We also derive several new approximate relations valid in the hydrodynamic regime, taking into account the effects of thermal conductivity and composition fluctuations for arbitrary space dimension. One approximate relation was heuristically obtained in our previous studies and verified using our extended simulation data on two-dimensional (2D) glass-forming systems. As a result, we provide the means to obtain, in any spatial dimension, all stress-correlation functions in terms of relaxation moduli and vice versa. The new approximate relations are tested using simulation data on 2D systems of polydisperse Lennard–Jones particles. [ABSTRACT FROM AUTHOR]

Abstract The requirement for temperature‐controlled storage can be challenging and expensive for the transportation and storage of biologics. Light‐assisted drying (LAD) is a new processing technique to prepare biologics for storage in a trehalose amorphous solid matrix at ambient temperatures. Samples are illuminated with near‐infrared laser light to speed dehydration. Previous work has shown LAD can prepare small‐volume (40 μL) samples, but the feasibility of applying LAD to larger samples remains unexplored. Here, LAD is applied to large‐volume samples (250 μL). Samples of a trehalose solution with an embedded protein were LAD processed and stored for 1 month. The end moisture contents of samples were determined after processing and storage. Thermal histories were monitored to determine optimal drying times. The trehalose matrix was characterized using polarized light imaging and Raman spectroscopy. Karl‐Fischer (KF) titration was used to measure the water content. The end moisture contents and thermal histories show high repeatability for LAD processing. Polarized light imaging demonstrates that the trehalose matrix was resistant to crystallization. Raman spectroscopy indicates uniform water distribution and KF titration reveals a low average water content (2.5%). LAD can stabilize large‐volume samples for dry‐state storage at ambient temperatures and offers a potential solution for cold‐chain storage challenges.

Compared to Zr-based bulk metallic glasses (BMGs), glass forming abilities (GFAs) of Hf-based counterparts limit practical applications. X-ray diffraction and transmission electron microscopy analysis revealed that only HfNiAl and CuHf2 crystal phases existed in Hf47Cu29Ni10Al14 master ingots. However, when partially substituting Ni with Ag or Co, the GFAs were remarkably improved. Particularly, alloying 3 at.% Ag resulted in an almost fully amorphous master ingot with a maximum thickness of 10.75 mm. Our experimental results conflict with conventional theories such as the deep eutectics theory. A large negative heat of mixing (HM) between constituent elements has been widely accepted as a key factor in enhancing GFAs. Our results posed a puzzling problem due to the non-negative HM between two similar elements either Ag and Cu or Co and Ni. To address the contradiction, a similar competition mechanism was proposed to elucidate the apparent difference in GFAs between quaternary and quinary alloys. Competition is triggered between similar elements when interacting with another element due to their analogous properties, which undermines the interaction between each of similar elements and another element and then suppresses crystal phases containing one similar element. To quantitatively describe this mechanism, we introduced a dimensionless parameter, χ. [ABSTRACT FROM AUTHOR]

We introduce a generalized machine learning framework to probabilistically parameterize upper-scale models in the form of nonlinear PDEs consistent with a continuum theory, based on coarse-grained atomistic simulation data of mechanical deformation and flow processes. The proposed framework utilizes a hypothesized coarse-graining methodology with manifold learning and surrogate-based optimization techniques. Coarse-grained high-dimensional data describing quantities of interest of the multiscale models are projected onto a nonlinear manifold whose geometric and topological structure is exploited for measuring behavioral discrepancies in the form of manifold distances. A surrogate model is constructed using Gaussian process regression to identify a mapping between stochastic parameters and distances. Derivative-free optimization is employed to adaptively identify a unique set of parameters of the upper-scale model capable of rapidly reproducing the system's behavior while maintaining consistency with coarse-grained atomic-level simulations. The proposed method is applied to learn the parameters of the shear transformation zone (STZ) theory of plasticity that describes plastic deformation in amorphous solids as well as coarse-graining parameters needed to translate between atomistic and continuum representations. We show that the methodology is able to successfully link coarse-grained microscale simulations to macroscale observables and achieve a high-level of parity between the models across scales.

We introduce a generalized machine learning framework to probabilistically parameterize upper-scale models in the form of nonlinear PDEs consistent with a continuum theory, based on coarse-grained atomistic simulation data of mechanical deformation and flow processes. The proposed framework utilizes a hypothesized coarse-graining methodology with manifold learning and surrogate-based optimization techniques. Coarse-grained high-dimensional data describing quantities of interest of the multiscale models are projected onto a nonlinear manifold whose geometric and topological structure is exploited for measuring behavioral discrepancies in the form of manifold distances. A surrogate model is constructed using Gaussian process regression to identify a mapping between stochastic parameters and distances. Derivative-free optimization is employed to adaptively identify a unique set of parameters of the upper-scale model capable of rapidly reproducing the system's behavior while maintaining consistency with coarse-grained atomic-level simulations. The proposed method is applied to learn the parameters of the shear transformation zone (STZ) theory of plasticity that describes plastic deformation in amorphous solids as well as coarse-graining parameters needed to translate between atomistic and continuum representations. We show that the methodology is able to successfully link coarse-grained microscale simulations to macroscale observables and achieve a high-level of parity between the models across scales.

We provide an overview of the different types of computational techniques developed over the years to study supercooled liquids, glassy materials and the physics of the glass transition. We organise these numerical strategies into four broad families. For each of them, we describe the general ideas without discussing any technical details. We summarise the type of questions which can be addressed by any given approach and outline the main results which have been obtained. Finally we describe two important directions for future computational studies of glassy systems.

Investigations on metallic glasses have increased significantly due to their obvious qualities such as high glass–forming ability, corrosion resistance, and chemical, mechanical, and magnetic properties. By considering the importance of Cobalt– and Iron–based metallic glasses with various Tantalum concentrations, a Monte Carlo simulation (Geant4 code) and Phy–X/PSD software were used to investigate their gamma–ray attenuation properties, such as mass attenuation coefficient, effective atomic number, and half–value layer for different photon energy ranges. The mass attenuation coefficient (MAC) was calculated numerically using the Phy–X/PSD software between 0.015 and 15 MeV, and the results were compared to Monte Carlo simulations. The mass attenuation coefficients of the alloys were ranged between 108.6 and 94.3 cm2/g for lowest the photon energy, while reduced to 0.0458 cm2/g at the high energy region. These results showed that the radiation protection effectiveness values may be correlated with the alloys' magnetization. The obtained results revealed that Tantalum density and larger atomic numbers are the most important factors in improving the radiation attenuation capabilities and then the shielding performance of the investigated glassy alloys. [ABSTRACT FROM AUTHOR]

Amorphous carbon nanotubes (a‐CNT) with up to four walls and sizes ranging from 200 to 3200 atoms have been simulated, starting from initial random configurations and using the Gaussian Approximation Potential. The important variables (like density, height, and diameter) required to successfully simulate a‐CNTs were predicted with the machine learning random forest technique. The width of the a‐CNT models ranged between 0.55–2 nm with an average inter‐wall spacing of 0.31 nm. The topological defects in a‐CNTs were analyzed and new defect configurations were observed. The electronic density of states and localization in these phases were discussed and delocalized electrons in the π subspace were identified as an important factor for inter‐layer cohesion. Spatial projection of the electronic conductivity favors axial transport along connecting hexagons, while non‐hexagonal parts of the network either hinder or bifurcate the electronic transport. A vibrational density of states was calculated and is potentially an experimentally comparable fingerprint of the material. The appearance of a low‐frequency radial breathing mode was discussed and the thermal conductivity at 300 K was estimated using the Green‐Kubo formula. [ABSTRACT FROM AUTHOR]

The solubilities and maximum supersaturation concentrations of an amorphous and the crystalline tetrahydrate and heptahydrate solids of disodium guanosine 5'‐monophosphate (GMP) in water‐methanol mixtures were measured in situ by Raman spectroscopy and focused beam reflectance measurement. The distinct Raman peaks of the amorphous form, crystalline hydrates, solution, and solvent were used for measurements of solubility and maximum supersaturation. Above 45 °C and at methanol fractions of 0.15–0.90, the tetrahydrate was the stable form, while below 40 °C and at methanol fractions of 0.15–0.60, the heptahydrate was the stable form. Especially, the tetrahydrate was stable in the methanol fraction > 0.7 at the temperature investigated. The solubility and supersaturated concentration values can be used to selectively produce amorphous, tetrahydrate, and heptahydrate solids of GMP by anti‐solvent crystallization. [ABSTRACT FROM AUTHOR]

Understanding crystallization behaviors is of utmost importance for developing robust amorphous pharmaceutical solids. Herein, the crystal growth behaviors of amorphous anti‐inflammatory drug nimesulide (NIME) are systemically investigated in the glassy and supercooled liquid state as a function of temperature. A sudden over‐tenfold increase is observed in the bulk crystal growth of NIME on cooling below its glass transition temperature (Tg). This fast growth behavior is known as a glass‐to‐crystal (GC) mode and has been reported in some molecular glasses. Fast surface crystal growth of NIME can persist up to Tg + 57°C with a weak jump in its growth rates at 30–40°C. In addition, surface crystal growth and GC growth of NIME exhibit an almost identical temperature dependence, supporting the view that GC growth is indeed a surface‐facilitated process. Moreover, the bubble‐induced fast crystal growth of NIME is observed in the interior of its supercooled liquid with approximately the same growth kinetics as surface crystal growth. These findings are relevant for a full understanding of the surface‐related crystallization behaviors and physical stability of amorphous pharmaceutical formulations. [ABSTRACT FROM AUTHOR]

Solid materials that deviate from the harmonic crystal paradigm exhibit characteristic anomalies in the specific heat and vibrational density of states (VDOS) with respect to Debye's theory predictions. The boson peak (BP), a low-frequency excess in the VDOS over Debye lawg(ω)∝ω2, is certainly the most famous among them; nevertheless, its origin is still subject of fierce debate. Recent simulation works provided strong evidence that localized one-dimensional string-like excitations (stringlets) might be the microscopic origin of the BP. In this work, we study the dynamics of acoustic phonons interacting with a bath of vibrating 1D stringlets with exponentially distributed size, as observed in simulations. We show that stringlets strongly renormalize the phonon propagator and naturally induce a BP anomaly in the VDOS, corresponding to the emergence of a dispersionless BP flat mode. Additionally, phonon-stringlet interactions produce a strong enhancement of sound attenuation and a dip in the speed of sound near the BP frequency, consistent with experimental and simulation data. The qualitative trends of the BP frequency and intensity are predicted within the model and shown to be in good agreement with previous observations. In summary, our results substantiate with a simple theoretical model the recent simulation results by Hu and Tanaka claiming the origin of the BP from stringlet dynamics., (© 2024 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.)

The deformation mechanism in amorphous solids subjected to external shear remains poorly understood because of the absence of well-defined topological defects mediating the plastic deformation. The notion of soft spots has emerged as a useful tool to characterize the onset of irreversible rearrangements and plastic flow, but these entities are not clearly defined in terms of geometry and topology. In this study, we unveil the phenomenology of recently discovered, precisely defined topological defects governing the microscopic mechanical and yielding behavior of a model 3D glass under shear deformation. We identify the existence of vortex-like and antivortex-like topological defects within the 3D nonaffine displacement field. The number density of these defects exhibits a significant anticorrelation with the plastic events, with defect proliferation-annihilation cycles matching the alternation of elastic-like segments and catastrophic plastic drops, respectively. Furthermore, we observe collective annihilation of these point-like defects via plastic events, with large local topological charge fluctuations in the vicinity of regions that feature strong nonaffine displacements. We reveal that plastic yielding is driven by several large sized clusters of net negative topological charge, the massive annihilation of which triggers the onset of plastic flow. These findings suggest a geometric and topological characterization of soft spots and pave the way for the mechanistic understanding of topological defects as mediators of plastic deformation in glassy materials., (© The Author(s) 2024. Published by Oxford University Press on behalf of National Academy of Sciences.)

Background: Poorly water-soluble medicaments continue to be a challenging, however, significant class of herbal drugs for the management of an extensive range of ailments. Solid dispersion (SD) has emerged as one of the most effective formulation approaches to enhance the dissolution of poorly water-soluble herbal drugs. Formulation of solid dispersion is one of the most effective methods to enhance the aqueous solubility of highly lipophilic drugs which belong to BCS class II and IV. An amorphous form of the drug is more unstable and highly soluble in water and is attained by formulating solid dispersion. Purpose: This review explains various physicochemical properties, criteria for carrier selection, and causes of instability of solid dispersion to improve the therapeutic potential of poorly water-soluble herbal drugs. Methodology: To classify and explain some newer techniques used nowadays along with solid dispersion which could prevent recrystallization and precipitation of drug. Some herbal drugs with high therapeutic value and poor aqueous solubility were also enlisted which could be formulated in the form of solid dispersion to have better oral bioavailability. Results: The solid dispersions studies have revealed better performance for the dissolution which might be due to its alteration from crystalline to amorphous form in addition to the adherence of hydrophilic carriers to the surface of poorly water-soluble herbal drugs. These techniques will assist in the formation of a more stable solid dispersion. Conclusion: The application of solid dispersion technique in enhancing the aqueous solubility of poorly aqueous soluble herbal drugs should direct to the constant and enhanced bioavailability, leading to an enhanced therapeutic potential.

Confined geometries offer useful and experimentally amenable mechanical testing arrangements in which to study the molecular and micro-structural processes which govern plastic yield in stress environments dominated by hydrostatic pressure over shear. However, the changes to macroscopic stress – strain behaviour that result from switching from an unconfined mode such as uniaxial compression to a confined one are often overlooked and display a surprising level of complexity, even for simple elastic – plastic constitutive models. Here we report a confinement induced strain hardening effect in polystyrene thin films achieved through repeated plastic loading with a cylindrical flat punch whose diameter is many times the initial film thickness. This high aspect ratio combines with constraint provided by film material surrounding the contact to generate a state of confined uniaxial strain in the indented region, rendering the deformation one dimensional. By repeated loading past the yield point into the plastic domain, we achieve a 66% increase in the confined yield stress, from 0.3 GPa to 0.5 GPa. Through finite element simulation and analytic modelling of the principal stresses and strains, we show that this effect arises not from intrinsic changes to the structure of the material, but rather residual stresses imparted during plastic loading. We contrast this effect with intrinsic changes to glassy thin films such as physical ageing and thermal cross-linking. [ABSTRACT FROM AUTHOR]

Understanding how liquid dynamics govern crystallization is critical for maintaining the physical stability of amorphous pharmaceutical formulations. In the present study, griseofulvin (GSF), a classic antifungal drug, was used as the model system to investigate the correlations between crystal growth kinetics and liquid dynamics. The temperature dependence of the kinetic part of the bulk crystal growth in a supercooled liquid of GSF was weaker than that of the structural relaxation time τα and scaled as τα−0.69. In the glassy state, GSF exhibited the glass‐to‐crystal (GC) growth behavior, whose growth rate was too fast to be under the control of the α‐relaxation process. Moreover, from the perspective of τα, the GC growth of GSF also satisfied the general condition for GC growth to exist: D/u < 7 pm, where D is the diffusion coefficient and u the speed of crystal growth. Also compared were the fast surface crystal growth rates us and surface relaxation times τsurface predicted by the random first‐order transition theory. Here, the surface crystal growth rate us of GSF exhibited a power‐law dependence upon the surface structural relaxation time: us ∝ τsurface−0.71, which was similar to that of the bulk growth rate and τα. These findings are important for understanding and predicting the crystallization of amorphous pharmaceutical solids both in the bulk and at the surface. [ABSTRACT FROM AUTHOR]

The main dynamical aspects of excitons as charged composite quasi-particles in an amorphous solid are examined by means of a powerful theoretical treatment. In fact, on the basis of that an exciton is a bound quantum state of an electron-hole pair after the hydrogen-atom model, the absolute value of an averaged (with respect to weighted discrete energy levels) exciton energy is defined and calculated for amorphous solids with parabolic energy bands. In particular, amorphous semiconductors of parabolic energy bands are considered. Prior to these considerations, an associated new reformulation of the non-relativistic, static, Schrödinger equation is given. [ABSTRACT FROM AUTHOR]

We investigate the pressure-induced structural phase transformation of amorphous silicon hexaboride (a-SiB6) using a constant pressure first principles approach. a-SiB6 is found to undergo a gradual phase transformation to a high-density amorphous phase (HDA) in which the average coordination number of both B and Si atoms is about 6. The HDA phase consists of differently coordinated motifs ranging from 4 to 8. B12 icosahedra are found to persist during compression of a-SiB6 and the structural modifications primarily occur around Si atoms and in the regions linking pentagonal pyramid-like configurations to each other. Upon pressure release, an amorphous structure, similar to the uncompressed one, is recovered, indicating a reversible amorphous-to-amorphous phase change in a-SiB6. When the electronic structure is considered, the HDA phase is perceived to have a wider forbidden band gap than the uncompressed one. [ABSTRACT FROM AUTHOR]

When stressed sufficiently, solid materials yield and deform plastically via reorganization of microscopic constituents. Indeed, it is possible to alter the microstructure of materials by judicious application of stress, an empirical process utilized in practice to enhance the mechanical properties of metals. Understanding the interdependence of plastic flow and microscopic structure in these nonequilibrium states, however, remains a major challenge. Here, we experimentally investigate this relationship, between the relaxation dynamics and microscopic structure of disordered colloidal solids during plastic deformation. We apply oscillatory shear to solid colloidal monolayers and study their particle trajectories as a function of shear rate in the plastic regime. Under these circumstances, the strain rate, the relaxation rate associated with plastic flow, and the sample microscopic structure oscillate together, but with different phases. Interestingly, the experiments reveal that the relaxation rate associated with plastic flow at time t is correlated with the strain rate and sample microscopic structure measured at earlier and later times, respectively. The relaxation rate, in this nonstationary condition, exhibits power-law, shear-thinning behavior and scales exponentially with sample excess entropy. Thus, measurement of sample static structure (excess entropy) provides insight about both strain rate and constituent rearrangement dynamics in the sample at earlier times. [ABSTRACT FROM AUTHOR]

The specific heat Cp and other properties of glasses (ranging from amorphous solids to disordered crystals) at low temperatures are well known to be markedly different from those in fully-ordered crystals. For decades, this qualitative, and even quantitative, universal behavior of glasses has been thoroughly studied. However, a clear understanding of its origin and microscopic nature, needless to say, a closed theory, is still lacking. To shed light on this matter, I review the situation in this work, mainly by compiling and discussing measured low-temperature Cp data of many glasses and disordered crystals, as well as highlighting a few exceptions to that "universality rule". Thus, one can see that, in contrast to other low-temperature properties of glasses, the magnitude of the "glassy" Cp excess at low temperature is far from being universal. Even worse, some molecular crystals without a clear sign of disorder exhibit linear coefficients in Cp larger than those found in many amorphous solids, whereas a few of the latter show negligible values. [ABSTRACT FROM AUTHOR]

Unlike the crystalline solids, the atomic arrangements in amorphous solids lack long-range translational and orientational order. Despite intense research activity on their structures, the details of how the atoms are packed in amorphous solids remain mysterious at present. Here, we propose a structure feature like polymers and estimate the nanoscale of short-range order (SRO) and medium-range order (MRO) in this description according to the boson peak in amorphous solids. The result supports the concepts that (a) the low-frequency local vibrations are defined by the characteristic length of nanoscale clusters and (b) a decisive scale correlation of solvent atoms, SRO and MRO is about 1:3:7 in amorphous solids. [ABSTRACT FROM AUTHOR]

Topological constraint theory (TCT) has revealed itself to be a powerful tool in interpreting the behaviors of amorphous solids. The theory predicts a transition between a “rigid” overconstrained network and a “floppy” underconstrained network as a function of connectivity or average coordination number, 〈r〉. The predicted results have been shown experimentally for various glassy materials, the majority of these being based on 4-fold-coordinate networks such as chalcogenide and oxide glasses. Here, we demonstrate the broader applicability of topological constraint theory to uniquely coordinated amorphous hydrogenated boron carbide (a-BC:H), based on 6-fold-coordinate boron atoms arranged into partially hydrogenated interconnected 12-vertex icosahedra. We have produced a substantial set of plasma-enhanced chemical vapor deposited a-BC:H films with a large range of densities and network coordination, and demonstrate a clear threshold in Young's modulus as a function of 〈r〉, ascribed to a rigidity transition. We investigate constraint counting strategies in this material and show that by treating icosahedra as “superatoms,” a rigidity transition is observed within the range of the theoretically predicted 〈r〉c value of 2.4 for covalent solids with bond-stretching and bond-bending forces. This experimental data set for a-BC:H is unique in that it represents a uniform change in connectivity with 〈r〉 and demonstrates a distinct rigidity transition with data points both above and below the transition threshold. Finally, we discuss how TCT can be applied to explain and optimize mechanical and dielectric properties in a-BC:H and related materials in the context of microelectronics applications.

Quantitative genomic and proteomic evaluation of human latent fingerprint depositions represents a challenge within the forensic field, due to the high variability in the amount of DNA and protein initially deposited. To better assess recovery techniques for touch depositions, we present a method to produce simple and customizable artificial fingerprints. These artificial fingerprint samples include the primary components of a typical latent fingerprint, specifically sebaceous fluid, eccrine perspiration, extracellular DNA, and proteinaceous epidermal skin material (i.e., shed skin cells). A commercially available emulsion of sebaceous and eccrine perspiration material provides a chemically-relevant suspension solution for fingerprint deposition, simplifying artificial fingerprint production. Extracted human genomic DNA is added to accurately mimic the extracellular DNA content of a typical latent print and comparable DNA yields are recovered from the artificial prints relative to human prints across surface types. Capitalizing on recent advancements in the use of protein sequence identification for human forensic analysis, these samples also contain a representative quantity of protein, originating from epidermal skin cells collected from the fingers and palms of volunteers. Proteomic sequencing by liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis indicates a high level of protein overlap between artificial and latent prints. Data are available via ProteomeXchange with identifier PXD015445. By including known quantities of DNA and protein into each artificial print, this method enables total DNA and protein recovery to be quantitatively assessed across different sample collection and extraction methods to better evaluate extraction efficiency. Collectively, these artificial fingerprint samples are simple to make, highly versatile and customizable, and accurately represent the biochemical composition and biological signatures of human fingerprints. [ABSTRACT FROM AUTHOR]

The formation of the sea urchin spicule skeleton requires the participation of hydrogel-forming protein families that regulate mineral nucleation and nanoparticle assembly processes that give rise to the spicule. However, the structure and molecular behavior of these proteins is not well established, and thus our ability to understand this process is hampered. We embarked on a study of sea urchin spicule proteins using a combination of biophysical and bioinformatics techniques. Our biophysical findings indicate that recombinant variants of the two most studied spicule matrix proteins, SpSM50 and SpSM30B/C (S. purpuratus) have a conformational landscape that include a C-terminal random coil/intrinsically disordered MAPQG sequence coupled to a conserved, folded N-terminal C-type lectin-like (CTLL) domain, with SpSM50 > SpSM30B/C with regard to intrinsic disorder. Both proteins possess solvent-accessible unfolded MAQPG sequence regions where Asn, Gln, and Arg residues may be accessible for protein hydrogel interactions with water molecules. Our bioinformatics study included seven other spicule matrix proteins where we note similarities between these proteins and rare, unusual proteins that possess folded and unfolded traits. Moreover, spicule matrix proteins possess three types of sequences: intrinsically disordered, amyloid-like, and folded protein-protein interactive. Collectively these reactive domains would be capable of driving protein assembly and hydrogel formation. Interestingly, three types of global conformations are predicted for the nine member protein set, wherein we note variations in the arrangement of intrinsically disordered and interactive globular domains. These variations may reflect species-specific requirements for spiculogenesis. We conclude that the molecular landscape of spicule matrix protein families enables them to function as hydrogelators, nucleators, and assemblers of mineral nanoparticles. [ABSTRACT FROM AUTHOR]

The West Nile Virus (WNV) NS2B-NS3 protease is an attractive target for the development of therapeutics against this arboviral pathogen. In the present investigation, the screening of a small library of fifty-eight synthetic compounds against the NS2-NB3 protease of WNV is described. The following groups of compounds were evaluated: 3-(2-aryl-2-oxoethyl)isobenzofuran-1(3H)-ones; eugenol derivatives bearing 1,2,3-triazolic functionalities; and indan-1,3-diones with 1,2,3-triazolic functionalities. The most promising of these was a eugenol derivative, namely 4-(3-(4-allyl-2-methoxyphenoxy)-propyl)-1-(2-bromobenzyl)-1H-1,2,3-triazole (35), which inhibited the protease with IC50 of 6.86 μmol L-1. Enzyme kinetic assays showed that this derivative of eugenol presents competitive inhibition behaviour. Molecular docking calculations predicted a recognition pattern involving the residues His51 and Ser135, which are members of the catalytic triad of the WNV NS2B-NS3 protease. [ABSTRACT FROM AUTHOR]

This study examines the relationship between female representation in different organisational positions and performance using a sample of Spanish secondary schools. These organizations have been usually depicted as ‘feminised environments’ although women in managerial positions are still underrepresented. Based on different theoretical approaches, we separately investigate the relationship between a greater female presence and school performance in three positions: a) as principal; b) on the management team; and c) as teachers. We also investigate if having a female leader exerts a significant mediator role on the relationship between greater female representation on the management team and teachers, respectively, and school performance. Our results reveal a positive and significant relationship between having a woman principal or a greater proportion of women teachers and school performance. However, the relationship between a high proportion of women on the management team and school performance is negative. We also find that a female principal does not play a significant role as mediator in the relationship between having a greater proportion of women on the management team and as teachers and school performance. [ABSTRACT FROM AUTHOR]

The cabbage stem flea beetle (CSFB), Psylliodes chrysocephala (Coleoptera: Chrysomelidae), has recently become a major pest species in winter oilseed rape in the Czech Republic. The susceptibility of CSFB populations from two localities to six pyrethroids, two neonicotinoids, one organophosphate and one oxadiazine was evaluated in 2015–2018 in glass vial experiments. The susceptibility of CSFB to thiacloprid and thiamethoxam was evaluated in feeding experiment in 2017 and 2018. High susceptibility of CSFB populations to lambda-cyhalothrin, cypermethrin, esfenvalerate, tau-fluvalinate, etofenprox, deltamethrin, chlorpyrifos, indoxacarb and acetamiprid was observed in the glass vial experiments. The LC50 and LC90 data obtained for pyrethroids in these experiments in 2015 represent baseline for CSFB resistance monitoring to pyrethroids in the Czech Republic. High tolerance of CSFB to thiacloprid of CSFB was demonstrated in glass vial and the feeding experiment, too. [ABSTRACT FROM AUTHOR]

In the area of laser material processing, versatile applications for cutting glasses and transparent polymers exist. However, parasitic effects such as the creation of step-like structures appear when laser cutting inside a transparent material. To date, these structures were only described empirically. This work establishes the physical and chemical mechanisms behind the observed effects and describes the influence of process and material parameters onto the creation of step-like structures in hydrogel, Dihydroxyethylmethacrylat (HEMA). By focusing laser pulses in HEMA, reduced pulse separation distance below 50 nm and rise in pulse energy enhances the creation of unintended step-like structures. Spatial resolved Raman-spectroscopy was used to measure the laser induced chemical modification, which results into a reduced breakdown threshold. The reduction in threshold influences the position of optical breakdown for the succeeding laser pulses and consequently leads to the step-like structures. Additionally, the experimental findings were supplemented with numerical simulations of the influence of reduced damage threshold onto the position of optical breakdown. In summary, chemical material change was defined as cause of the step-like structures. Furthermore, the parameters to avoid these structures were identified. [ABSTRACT FROM AUTHOR]

We evaluated the durability of cadmium telluride (CdTe) solar cells upon proton beam irradiation as well as the possibility of achieving a dosimeter usable in proton beam therapy by applying 100 MeV of pencil beam scanning (PBS) irradiation. Specifically, a 100 MeV proton PBS beam was applied at irradiation doses of 0, 1012, 1013, 1014, and 1015 cm-2. According to the results, the remaining factors (defined as the ratio of the degraded value to the initial value) of open-circuit voltage (Voc), short-circuit current (Jsc), fill-factor (FF), and efficiency (ƞ) which are solar cell performance parameters, were approximately 89%, 44%, 69%, and 30%, respectively, compared to those of the reference cell (without irradiation) at the highest dose of 1×1015 cm-2. In particular, the conversion efficiency, which is the main factor, was approximately 70% of that of the reference cell even at a high fluence of 1×1014 cm-2. In addition, we observed the projected range of the hydrogen atoms based on the PBS beam energy using the Tool for Particle Simulation software and assessed the amount of fluence accumulated in a CdTe cell. As the energy increased, the fluence accumulated inside the cell tended to decrease owing to the characteristics of the Bragg peak of the proton. Thus, the radiation damage to the cell induced by the proton beam was reduced. The results of this study are expected to provide valuable reference information for research on dosimetry sensors composed of thin-film solar cells, serving as the basis for future application in proton beam therapy with CdTe solar cells. [ABSTRACT FROM AUTHOR]

This article proposes the coupling of the recombinant protein avidin to the polysaccharide gellan gum to create a modular hydrogel substrate for 3D cell culture and tissue engineering. Avidin is capable of binding biotin, and thus biotinylated compounds can be tethered to the polymer network to improve cell response. The avidin is successfully conjugated to gellan gum and remains functional as shown with fluorescence titration and electrophoresis (SDS-PAGE). Self-standing hydrogels were formed using bioamines and calcium chloride, yielding long-term stability and adequate stiffness for 3D cell culture, as confirmed with compression testing. Human fibroblasts were successfully cultured within the hydrogel treated with biotinylated RGD or biotinylated fibronectin. Moreover, human bone marrow stromal cells were cultured with hydrogel treated with biotinylated RGD over 3 weeks. We demonstrate a modular and inexpensive hydrogel scaffold for cell encapsulation that can be equipped with any desired biotinylated cell ligand to accommodate a wide range of cell types. [ABSTRACT FROM AUTHOR]

This study investigated how the presence of others and anticipated distributions for self influence children’s fairness-related decisions in two different socio-moral contexts. In the first part, three- and five-year-old children (N = 120) decided between a fair and an unfair wheel of fortune to allocate resources (procedural justice). In the second part, they directly chose between two distributions of resources (distributive justice). While making a decision, each child was either observed by the affected group members (public), alone (private), or no others were introduced (non-social control). Children choose the fair option more often when others were affected (independently of their presence) only in the procedural justice task. These results suggest that using a fair procedure to distribute resources allows young preschoolers to overcome selfish tendencies. [ABSTRACT FROM AUTHOR]

Because of the inherent complexity of bioprocesses, mathematical models are more and more used for process design, control, optimization, etc. These models are generally based on a set of biochemical reactions. Model equations are then derived from mass balance, coupled with empirical kinetics. Biological models are nonlinear and represent processes, which by essence are dynamic and adaptive. The temptation to embed most of the biology is high, with the risk that calibration would not be significant anymore. The most important task for a modeler is thus to ensure a balance between model complexity and ease of use. Since a model should be tailored to the objectives, which will depend on applications and environment, a universal model representing any possible situation is probably not the best option. [ABSTRACT FROM AUTHOR]

The whiskey industry is dominated by whiskey styles with recipes that contain corn as the primary grain. However, little research has been conducted to investigate whiskey specific distinctions arising from different corn varieties and growing environments (i.e. terroir). Further, no studies have investigated the aroma or flavor impacts of different varieties and terroirs. Here, three different commodity yellow dent hybrid corn varieties were grown on different farms in Texas, spanning from the Texas Panhandle to the Mexico-United States border. Using novel small-batch mashing techniques, a newly developed new-make (i.e. unaged whiskey,immediate by-product of distillation) bourbon sensory lexicon, a trained sensory panel, high-performance liquid chromatography, and gas chromatography-mass spectrometry/olfactometry (GC-MS/O), we report for the first time a method for evaluating sample effects on alcohol yield and flavor in new-make bourbon whiskey. We discover that variety, terroir and their interactions, previously ignored, can substantially affect valuable sensory aspects of whiskey, suggesting the importance of scientifically evaluating corn genetics and agronomy for developing better whiskey. Excitingly, our data suggest milled corn with higher levels of benzadehyde, readily measured by GC-MS/O, correlates with improved sensory aspects of distillate, which must be expensively evaluated using a trained human sensory panel. [ABSTRACT FROM AUTHOR]

Kin-biased behavior (that is responding differentially to kin and non-kin) is thought to be adaptive in many social interactions. One example of this kin bias is behaving less aggressively toward a relative than a non-relative, a behavior which yields inclusive fitness benefits. However, data are lacking about the ability of animals to weigh their preference for kinship and the density of conspecifics simultaneously and to respond accordingly. Fire salamanders (Salamandra infraimmaculata) larviposit in high densities in ponds. Thus, larvae of different females confront competition and predation by other larvae. We studied whether larvae prefer their kin over particular density or vice versa. We experimentally used a transparent glass aquarium with inner chambers to test the responses of a focal larva toward its siblings and non-siblings. Specifically, we quantified the time a focal larva spent near its siblings or non-siblings, presented in varying densities, and the aggression level it demonstrated. We found that focal larvae spent more time near non-siblings if non-sibling and sibling groups were of equal density. The focal larvae were also more aggressive toward non-siblings. The results may be explained by the cannibalistic nature of these larvae: high density may provide more opportunities for food, especially when non-siblings are present. Further explanations for these findings may include other advantages of staying in a larger group and/or the stronger olfactory and visual stimulation offered by groups compared to a single individual. These findings suggest that larvae make differential responses toward conspecifics depending simultaneously on the level of relatedness and the density of the group. Such responses have important implications for social—aggregation decisions and may especially affect the fitness of cannibalistic species. [ABSTRACT FROM AUTHOR]

Measurements of Young’s moduli are mostly evaluated using strong assumptions, such as sample homogeneity and isotropy. At the same time, descriptions of measurement parameters often lack detailed specifications. Many of these assumptions are, for soft hydrogels especially, not completely valid and the complexity of hydrogel microindentation demands more sophisticated experimental procedures in order to describe their elastic properties more accurately. We created an algorithm that automates indentation data analysis as a basis for the evaluation of large data sets with consideration of the influence of indentation depth on the measured Young’s modulus. The algorithm automatically determines the Young’s modulus in indentation regions where it becomes independent of the indentation depth and furthermore minimizes the error from fitting an elastic model to the data. This approach is independent of the chosen elastic fitting model and indentation device. With this, we are able to evaluate large amounts of indentation curves recorded on many different sample positions and can therefore apply statistical methods to overcome deviations due to sample inhomogeneities. To prove the applicability of our algorithm, we carried out a systematic analysis of how the indentation speed, indenter size and sample thickness affect the determination of Young’s modulus from atomic force microscope (AFM) indentation curves on polyacrylamide (PAAm) samples. We chose the Hertz model as the elastic fitting model for this proof of principle of our algorithm and found that all of these parameters influence the measured Young’s moduli to a certain extent. Hence, it is essential to clearly state the experimental parameters used in microindentation experiments to ensure reproducibility and comparability of data. [ABSTRACT FROM AUTHOR]

Considering the essential role of chemotaxis of adherent, slow-moving cells in processes such as tumor metastasis or wound healing, a detailed understanding of the mechanisms and cues that direct migration of cells through tissues is highly desirable. The state-of-the-art chemotaxis instruments (e.g. microfluidic-based devices, bridge assays) can generate well-defined, long-term stable chemical gradients, crucial for quantitative investigation of chemotaxis in slow-moving cells. However, the majority of chemotaxis tools are designed for the purpose of an in-depth, but labor-intensive analysis of migratory behavior of single cells. This is rather inefficient for applications requiring higher experimental throughput, as it is the case of e.g. clinical examinations, chemoattractant screening or studies of the chemotaxis-related signaling pathways based on subcellular perturbations. Here, we present an advanced migration assay for accelerated and facilitated evaluation of the chemotactic response of slow-moving cells. The revised chemotaxis chamber contains a hydrogel microstructure–the migration arena, designed to enable identification of chemotactic behavior of a cell population in respect to the end-point of the experiment. At the same time, the assay in form of a microscopy slide enables direct visualization of the cells in either 2D or 3D environment, and provides a stable and linear gradient of chemoattractant. We demonstrate the correctness of the assay on the model study of HT-1080 chemotaxis in 3D and on 2D surface. Finally, we apply the migration arena chemotaxis assay to screen for a chemoattractant of primary keratinocytes, cells that play a major role in wound healing, being responsible for skin re-epithelialization and a successful wound closure. In direction of new therapeutic strategies to promote wound repair, we identified the chemotactic activity of the epithelial growth factor receptor (EGFR) ligands EGF and TGFα (transforming growth factor α). [ABSTRACT FROM AUTHOR]

Silk fibroin-derived polypeptides (FDPs) are polypeptides resulting from the enzymatic separation of the hydrophobic crystalline (Cp) and hydrophilic electronegative amorphous (Cs) components of silk fibroin (SF). The role of these polypeptides in promoting the nucleation of hydroxyapatite (HA) has been previously investigated, yet is still not fully understood. Here we study the potential of HA mineralization via FDPs incorporated at 1:10, 1:2 and 1:1 in a plastically compressed (PC) and dense collagen (DC) scaffold. Scaffolds were immersed in simulated body fluid (SBF) at physiological conditions (pH = 7.4, 37°C) to promote biomineralization. The effect of Cs and Cp to promote HA nucleation was investigated at different time points, and compared to pure DC scaffolds. Characterization of Cs and Cp fragments using Liquid Chromatography–Mass Spectrometry (LCMS) showed little difference in the amino acid composition of the FDPs. Results obtained in vitro using Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR), Scanning Electron Microscopy (SEM) X-Ray Diffraction (XRD) and mass analysis showed little difference between scaffolds that incorporated Cs, Cp, and DC hydrogels. These results demonstrated that silk FDPs incorporation are not yet suitable to promote HA nucleation in vivo without further refining the collagen-FDP system. [ABSTRACT FROM AUTHOR]

Development of eye tissue is initiated by a conserved set of transcription factors termed retinal determination network (RDN). In the fruit fly Drosophila melanogaster, the zinc-finger transcription factor Glass acts directly downstream of the RDN to control identity of photoreceptor as well as non-photoreceptor cells. Tight control of spatial and temporal gene expression is a critical feature during development, cell-fate determination as well as maintenance of differentiated tissues. The molecular mechanisms that control expression of glass, however, remain largely unknown. We here identify complex regulatory mechanisms controlling expression of the glass locus. All information to recapitulate glass expression are contained in a compact 5.2 kb cis-acting genomic element by combining different cell-type specific and general enhancers with repressor elements. Moreover, the immature RNA of the locus contains an alternative small open reading frame (smORF) upstream of the actual glass translation start, resulting in a small peptide instead of the three possible Glass protein isoforms. CRISPR/Cas9-based mutagenesis shows that the smORF is not required for the formation of functioning photoreceptors, but is able to attenuate effects of glass misexpression. Furthermore, editing the genome to generate glass loci eliminating either one or two isoforms shows that only one of the three proteins is critical for formation of functioning photoreceptors, while removing the two other isoforms did not cause defects in developmental or photoreceptor function. Our results show that eye development and function is largely unaffected by targeted manipulations of critical features of the glass transcript, suggesting a strong selection pressure to allow the formation of a functioning eye. [ABSTRACT FROM AUTHOR]

Silicon double-paddle oscillators (DPOs) have been successfully used for measuring the elastic properties of amorphous films down to 10 mK (see, e.g., Fefferman et al. in (J Low Temp Phys 187:654, 2017); Liu et al. in (Phys Rev Lett 113:025503, 2014). Until now, our group has used a wet dilution refrigerator for the lowest temperature measurements. We present measurements taken on a BlueFors cryogen-free dilution refrigerator that demonstrate an extreme sensitivity of the thermal coupling of the DPO to its environment. These measurements show that it is necessary to enclose the DPO in a shield at the mixing chamber (MXC) temperature. Any gaps in the shield limit its effectiveness, even if there is no line-of-sight path to the DPO. In the absence of a cryogenic hermetic shield surrounding the DPO, turning off the pulse tube while maintaining the MXC and still temperatures leads to heating of the DPO. This demonstrates that any heating of the sample due to pulse tube vibrations is a less important effect. [ABSTRACT FROM AUTHOR]