Small angle scattering is frequently applied to study the anisotropy in complex soft matter systems. One emerging application is to probe the multi-scale structure in food matrices; while few models ...are available to describe the anisotropic scattering pattern in a quantitative, yet simple manner. For this purpose, anisotropy is introduced to the Guinier–Porod model to study the scattering from non-spherical objects with a preferred orientation. This generalised anisotropic Guinier–Porod model can be adapted to approximate the sector scattering from both cylinders and ellipsoids (both prolate and oblate). In practice, it is applied to describe the anisotropic scattering from fibres in a meat analogue made of calcium caseinate. A good agreement is found between fitted dimensions of the fibres and those observed from the microscopy image. The effect of orientation distribution on the shape and intensity of the scattering pattern is further discussed and three means to obtain the orientation distribution of the symmetry axis are proposed. Given the model is straightforward and the fitting remains phenomenological, it provides a novel approach to extract information from complex food systems.
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•Anisotropy is introduced to the Guinier Porod model.•The model describes the small angle scattering from non-spherical objects with preferred orientation.•The model can study the anisotropic small angle scattering from fibres in a meat analogue.
Small angle neutron scattering (SANS) responses of particulate silica as disordered and ordered porous and non-porous powders were obtained. Each classification provided distinct scattering patterns ...which were fitted and analysed using Guinier-Porod and mass-surface fractal (msf) models. The resulting particle dimensions showed good agreement with the same from nitrogen gas adsorption analyses. Additionally, the excellent fit of the msf model to the non-porous silica scattering response resulted in an agreement between the mass and surface fractal dimension values for it and similar analyses and results published previously for fumed silica. The msf fitting gave additional insight into particle and cluster scattering dimensions with particle dimensions being consistent with those from the G-P analyses.
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•Small angle neutron scattering analyses of powdered silica.•Ordered, disordered, and nonporous silica scattering effects identified.•Particle and scattering entity dimensions defined and equated.•Fractal analysis provides insight into surface roughness.•Combined standard uncertainty defined for each derived variable.
U Državnim arhivima u Zadru i Dubrovniku čuvaju se obiteljske memorabilije i rukopisna građa na temelju kojih se rekonstruira životopis Marije Natali Zamagna (1807-1891). Njegov tijek otkriva životni ...prostor žene u 19. stoljeću ispunjen majčinskim i obiteljskim poslanjem u duhu običaja i pravila vremena. Propitivanjem različitih aspekata uloge žene i njezina statusa unutar obiteljskih i društvenih odnosa, iščitava se povijest žene i njezina mentaliteta, strategije braka i majčinstva.
Suspensions of solid lipid nanoparticles (SLNs) stabilized with emulsifiers have been extensively investigated (since the 1990s) as drug carriers, although details of their ultrastructure are poorly ...defined. Previously, a novel microwave‐assisted microemulsion‐based technique to prepare SLNs was reported. To understand the detailed internal structure of these SLNs, ultra‐small angle neutron scattering (USANS) and small angle neutron scattering (SANS) experiments are conducted on suspensions of hydrogenated stearic acid SLNs stabilized with hydrogenated Tween 20 surfactant in D2O. Together, SANS and USANS gives a combined Q range of 0.000047 to 0.6 Å−1 (corresponding to a size range of ≈1 nm–15 µm). This extended Q range allows a comprehensive understanding of the hierarchical structure of SLNs. The data are consistent with the multi‐length scale structure of SLNs having polydispersed large particles with roughened surfaces at the microscale level. At the nanoscale level, the results are consistent with the SLNs having an ellipsoidal shape intermediate between spheres and rods, with a crossover from mass fractals to surface fractals. The elucidation of this structure is particularly important given that the structure influences the stability and drug release properties of the nanoparticles. These results assist in the development of systems with desired shape and properties.
Neutron scattering techniques are successfully used to probe the hierarchical structure of solid lipid nanoparticles (SLNs). The results indicate multi‐length scale structure of SLNs having polydispersed large particles with roughened surfaces at the microscale level. At the nanoscale level, the SLNs have an ellipsoidal shape intermediate between spheres and rods, with a crossover from mass fractals to surface fractals.
To accurately model double-stranded DNA in a manner that is computationally efficient, coarse-grained models of DNA are introduced, where model parameters are selected by fitting the spectrum of ...observable DNA knots: We develop a general method to fit free parameters of coarse-grained chain models by comparing experimentally obtained knotting probabilities of short DNA chains to knotting probabilities that are computed in Monte Carlo simulations, resulting in coarse-grained DNA models which are tailored to reflect DNA topology in the best possible way. The method is exemplified by fitting ideal chain models as well as a bead-spring model with excluded volume interactions, to model double-stranded DNA for physiological as well as for high salt concentrations. The resulting coarse-grained DNA models predict the correct persistence length and effective diameter of double-stranded DNA, and can in principle be used for dynamical investigations using Molecular Dynamics. Our modelling ansatz thus provides a blueprint for building coarse-grained models of polymers, which are solely based on knotting spectra.
We analyzed the structure of horseradish peroxidase (HRP) under denaturing conditions of 9 M urea or 6 M guanidine hydrochloride (GdnHCl). Far-UV circular dichroism (CD) spectra indicated the ...existence of native-like secondary structure of holo-HRP in 9 M urea. In addition, slight changes in near-UV and Soret region CD spectra of holo-HRP in 9 M urea suggest that the tertiary structure of holo-HRP and the binding of heme remain partially intact in this condition. A transition in the thermal unfolding transition curve of holo-HRP in 9 M urea indicated the existence of a considerable amount of secondary structure. However, no secondary structure, tertiary structure, or interaction between heme and HRP were observed in holo-HRP in 6 M GdnHCl. Small-angle X-ray scattering indicated that although distal and proximal domains of holo-HRP in 9 M urea might be partially unfolded, the central region that contains the heme might maintain its tertiary structure. Our results suggest that retention of the heme is essential for maintenance of the structure of HRP under highly denaturing conditions.
The angular scattered-light intensity, or scattering curve, for a spherical particle is known to display approximate power-law structures when formulated in terms of the scattering wave vector and ...plotted in log–log scale. Empirically based studies reveal that the structures have common behavior across a wide variety of particle size and refractive index. These patterns, as they are called, are useful as they can relate the scattering curve to particle properties in some cases. The cause of the patterns, however, has not been satisfactorily derived from first principles until recently and the formal analysis has yet to be applied to nonspherical particles. This paper reviews the patterns for spherical particles and shows how they can be derived from the Maxwell equations for weakly refracting particles. The derivation is then extended to spheroidal particles where similar patterns are seen. A graphically based technique is used to show how interference between particular regions within a particle can account for so-called crossovers, which are transitions from one power-law to another in a given curve. Application of the phasor analysis to strongly refractive spheres and spheroids demonstrates that the interference interpretation remains valid despite the absence of a direct analytical derivation from the Maxwell equations. Finally, several laboratory experiments are discussed that demonstrate how the patterns are seen in measurements and how they may be used in practice to size particles.
► Power-law patterns in scattering from spherical particles is reviewed. ► New patterns for nonspherical particles are discussed. ► The patterns are derived from first principles. ► Explanations for the patterns are given and interpreted. ► Laboratory measurements displaying the patterns are discussed.
Baghouse dust collectors are using in the drying unit of Beni Idir situated in Beni-Idir Khouribga city, Morocco, to retrieve phosphates particles from dust air-drying before its expulsion through ...the smokestacks. The phosphate dust samples used in this study were taken from the filtration chamber of the baghouse dust collectors. The first sample (S1) is untreated calcium phosphate dust, the second (S2) is the calcium phosphate dust from the outside of filter media while the third one (S3) is the calcium phosphate dust from the inside of filter media which causes clogging depth. In this paper, the rheology and the small-angle X-ray scattering (SAXS) of the three samples were investigated to elucidate the changes in terms of local structure, the viscosity, and the shear stress parameters. The rheological behavior of the dust samples was investigated for a solid mass concentration ranging from 50 to 60%, the three samples (S1) (S2) and (S3) had a solid mass concentration of C1=60%, C2=55% and C3=50% and a shear rate in the range from 1 to 1000 s
. The results indicated that during the filtration process, the pseudo-plastic behavior of the dust phosphate changed to that of Bingham. Comparing the results of the sample’s viscosity, we found that the viscosity decreased during the process filtration. The SAXS results suggested that the dust phosphate samples possess a fractal surface structure of enormous dust particles with a rough surface interface. This new study highlights the rheological behavior of grain phosphates that could be extrapolated to other mining powder as grains material or in solution. It is important to understand the rheological characteristics of materials, their flow, and the subsequent deformation of matter as a result of the flow.
The article examines the medicalization of pregnancy and childbirth and the tendency to humanize or demedicalize childbirth. The concept of childbirth dramatically changed in Western countries over ...the last century. Pregnancy and childbirth were still considered to be a natural phenomenon at the beginning of the 20th century. In the second half of the 20th century, which coincides with more intense development of gynaecology and obstetrics and the related technology, pregnancy and childbirth became the subject of the jurisdiction of medicine. Medicalization in Peter Conrad's terms is a process by which non-medical problems become defined as medical, which is also related to the implementation of medical interventions. A descriptive research method was used to perform a literature review related to the medicalization of pregnancy and childbirth. In addition to a general overview of the theme, the review focused on the Slovenian context. Discussions about the medicalization of pregnancy and childbirth and natural childbirth create ambivalence, since technological advances also help to save lives. The feminist critique sees the medicalization of pregnancy and childbirth in the function of control over women's bodies and reproduction. The process of humanization therefore focuses on woman and her ability to make independent decisions related to pregnancy and childbirth. Through the literature review, it is indicated that there is a need for further empirical research to explain more clearly the interweaving of these two perspectives, especially in Slovenia, where such studies are extremely limited. Adapted from the source document.
The interaction of proteins bound at distant sites on a nucleic acid chain plays an important role in many molecular biological processes. Contact between the proteins is established by looping of ...the intervening polymer, which can comprise either double- or single-stranded DNA or RNA, or interphase or metaphase chromatin. The effectiveness of this process, as well as the optimal separation distance, is highly dependent on the flexibility and conformation of the linker. This article reviews how the probability of looping-mediated interactions is calculated for different nucleic acid polymers. In addition, the application of the equations to the analysis of experimental data is illustrated.
This article describes how the probability of looping-mediated interactions is calculated for different nucleic acid polymers such as double- or single-stranded DNA or RNA, or interphase or metaphase chromatin.
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