Fine Structure Effects Research Articles

Structure based release kinetics analysis of doxazosin mesylate sustained-release tablets using micro-computed tomography

The structures of solid dosage forms determine their release behaviors and are critical attributes for the design and evaluation of the solid dosage forms. Here, the three-dimensional (3D) structures of doxazosin mesylate sustained-release tablets (DM SRT) as reference listed drug (RLD) and a generic preparation were parallelly assessed by micro-computed tomography (micro-CT). There were no significant differences observed in the release profiles between the RLD and the generic formulation in the conventional dissolution, but the generic preparation released slightly faster in media with ethanol for an alcohol-induced dose-dumping test. With their 3D structures obtained via micro-CT determination, the unique release behaviors of both RLD and the generic were investigated for samples from dissolution tests to reveal the effects of internal fine structure on the release kinetics. The structural parameters for both preparations were similar in conventional dissolution test, whilst the dissolutions in ethanol media of RLD were more or less distinguished from that of generic preparations, attributing to their static and dynamic structures. Furthermore, the findings revealed that the presence of ethanol accelerated the dissolution and induced changes in the internal structure of both the RLD and the generic preparations. Moreover, the structure parameters like volume and area of outer contour, remaining solid volume and cavity volume were not equivalent between the two formulations in 40 % ethanol. In conclusion, the structure data obtained from this study provided valuable insights into the diverse release behaviors observed in various modified-release formulations in drug development and quality control.

Eigenvalue spectra of finely structured random matrices.

Random matrix theory allows for the deduction of stability criteria for complex systems using only a summary knowledge of the statistics of the interactions between components. As such, results like the well-known elliptical law are applicable in a myriad of different contexts. However, it is often assumed that all components of the complex system in question are statistically equivalent, which is unrealistic in many applications. Here we introduce the concept of a finely structured random matrix. These are random matrices with element-specific statistics, which can be used to model systems in which the individual components are statistically distinct. By supposing that the degree of "fine structure" in the matrix is small, we arrive at a succinct "modified" elliptical law. We demonstrate the direct applicability of our results to the niche and cascade models in theoretical ecology, as well as a model of a neural network, and a directed network with arbitrary degree distribution. The simple closed form of our central results allow us to draw broad qualitative conclusions about the effect of fine structure on stability.

On the computation of moments in the Super-Transition-Arrays model for radiative opacity calculations

In the Super-Transition-Array statistical method for the computation of radiative opacity of hot dense matter, the moments of the absorption or emission features involve partition functions with reduced degeneracies, occurring through the calculation of averages of products of subshell populations. In the present work, we discuss several aspects of the computation of such peculiar partition functions, insisting on the precautions that must be taken in order to avoid numerical difficulties. In a previous work, we derived a formula for supershell partition functions, which takes the form of a functional of the distribution of energies within the supershell and allows for fast and accurate computations, truncating the number of terms in the expansion. The latter involves coefficients for which we obtained a recursion relation and an explicit formula. We show that such an expansion can be combined with the recurrence relation for shifted partition functions. We also propose, neglecting the effect of fine structure as a first step, a positive-definite formula for the Super-Transition-Array moments of any order, providing an insight into the asymmetry and sharpness of the latter. The corresponding formulas are free of alternating sums. Several ways to speed up the calculations are also presented.

Effects of heat moisture treatment on the structure and digestibility of high amylose starch-lauric acid complexes

In this study, we investigated the effects of heat moisture treatment (HMT) on the structure and in vitro digestibility of high-amylose starch-lauric acid complexes, revealing the relationship between the effects of moisture content (MC) and fine structure in vitro digestibility of the complexes. The results showed that HMT changed the structure of the complexes, while MC significantly affected the resistant starch content, complex index, and relative crystallinity of the complexes. Compared with complexes without HMT, complexes prepared at 25% MC had the highest resistant starch content (63.97%), complex index (75.77%), and relative crystallinity (15.28%). The Fourier transform infrared spectroscopy results showed that the short-range order of the complexes was affected by the MC, particularly at 25% MC, which exhibited the highest short-range order among the complexes. Nuclear magnetic resonance spectroscopy results showed that the high amylose starch-lauric acid complexes prepared at an MC of 25% had a high V-shaped single-helix complex, which belonged to the V6-type crystalline structure. Small angle X-ray scattering data further indicated that complexes at this MC displayed a tighter structure with a larger lamellar thickness (dc) in the crystalline region. Therefore, we believe that the MC altered the fine structure of the complexes, which in turn affected their in vitro digestibility.

Fine structure and hypoglycemic effect of a galactoglucan from the bulbs of Lanzhou lily

The present research aimed to further identify the fine structure, morphology, and thermal behaviors of a galactoglucan BHP-2 derived from Lanzhou lily bulbs through partial acid hydrolysis, methylation, 2D NMR (1H1H COSY, HSQC, and HMBC), scanning electron microscopy (SEM) and thermogravimetric-differential thermal analysis (TG-DTA). Additionally, the study assessed the potential in vitro hypoglycemic effect of BHP-2 by examining its inhibitory effect on α-glucosidase and α-amylase. The results indicated that the main backbone composition of BHP-2 consisted of →4)-α-D-Glcp-(1→, →3)-β-D-Glcp-(1 → and →6)-β-D-Galp-(1→, while the side chain composition predominantly featured →4)-α-D-Glcp-(1→, →3,5)-α-L-Araf-(1 → and →3)-β-D-Galp-(1→, attached to the C-2 and/or C-3 positions of →4)-α-D-Glcp-(1→. Terminal residues consisted of α-D-Glcp-(1 → and β-L-Araf-(1→. BHP-2 exhibited excellent thermal stability, with a microscopic surface characterized by tightly packed sheets and numerous spiral depressions, which might contribute to its remarkable in vitro hypoglycemic effect. BHP-2 showed competitive inhibition of α-amylase and mixed non-competitive inhibition of α-glucosidase, with respective IC50 values of 0.31 and 0.18 mg/mL, closely resembling to those of acarbose (0.27 and 0.12 mg/mL). These findings suggested that BHP-2 had potential as an additive for glycemic intervention.

EEG-based assessment of temporal fine structure and envelope effect in mandarin syllable and tone perception.

Abstract In recent years, speech perception research has benefited from low-frequency rhythm entrainment tracking of the speech envelope. However, speech perception is still controversial regarding the role of speech envelope and temporal fine structure, especially in Mandarin. This study aimed to discuss the dependence of Mandarin syllables and tones perception on the speech envelope and the temporal fine structure. We recorded the electroencephalogram (EEG) of the subjects under three acoustic conditions using the sound chimerism analysis, including (i) the original speech, (ii) the speech envelope and the sinusoidal modulation, and (iii) the fine structure of time and the modulation of the non-speech (white noise) sound envelope. We found that syllable perception mainly depended on the speech envelope, while tone perception depended on the temporal fine structure. The delta bands were prominent, and the parietal and prefrontal lobes were the main activated brain areas, regardless of whether syllable or tone perception was involved. Finally, we decoded the spatiotemporal features of Mandarin perception from the microstate sequence. The spatiotemporal feature sequence of the EEG caused by speech material was found to be specific, suggesting a new perspective for the subsequent auditory brain-computer interface. These results provided a new scheme for the coding strategy of new hearing aids for native Mandarin speakers. Highlights

Effects of Starch Molecular Structure and Physicochemical Properties on Eating Quality of Indica Rice with Similar Apparent Amylose and Protein Contents.

It is important to clarify the effects of starch fine structure and protein components on the eating quality of indica rice. In this study, seven indica rice varieties with similar apparent amylose content (AAC) and protein content (PC) but different sensory taste values were selected and compared systematically. It was found that except for AAC and PC, these varieties showed significant differences in starch molecular structure and protein components. Compared with rice varieties with a low sensory taste value, varieties with a higher sensory taste value showed significantly lower amylose and higher amylopectin short chains (degree of polymerization 6-12) content; the protein component showed that the varieties with good taste value had higher albumin and lower globulin and glutelin content (p < 0.05). Rice varieties with lower AC, globulin, and glutelin content, as well as a higher content of albumin and amylopectin short chains, resulted in a higher swelling factor, peak viscosity, breakdown value, and ratio of hardness to stickiness, in which condition cooked rice showed a higher sensory taste value. Moreover, this study indicated that rice varieties with a higher content of albumin and amylopectin short chains were conducive to the good appearance of cooked rice. This study lays the foundation for the taste evaluation of good-tasting indica rice.

Dynamic response of a multi-scale layered saturated porous half-space due to seismic dislocation source by using a revised dynamic stiffness matrix method

The study investigating the dynamic response of seismic dislocation source in a layered saturated porous half-space, particularly the multi-scale characteristic of half-space, from crustal to geotechnical scale, is still lacking in the literature. particularly in will lead to the computation bottlenecks for multi-scale seismic wave propagation. Based on Biot's theory of wave propagation in a fluid-saturated porous solid, a dynamic stiffness matrix method is proposed to investigate the dynamic response of a multi-scale layered saturated porous half-space due to the seismic dislocation source. Assembling each layer stiffness matrix in the frequency-wavenumber domain, the global dynamic stiffness matrix is constructed to avoid errors accumulative compared to the reflection and transmission matrix method. The divergent index terms of the stiffness matrix with respect to thickness and wavenumber are extracted to revise the dynamic stiffness matrix adapted for multi-scale half-space. The seismic dislocation source action is equal to the external forces imposed on the total saturated porous half-space, which can obtain the dynamic response by using revised dynamic stiffness matrix method. The accuracy of the proposed method is verified via the comparison between the calculated results and of three published literatures. The multi-scale model with realistic near-surface fine structure is selected to investigate the effects of superficial fine structures on the dynamic responses. The numerical simulations results show that the presence of low-velocity saturated porous layers has a prominent impact on ground motion. The dynamic response seems to be sensitive to the porosity conditions, especially for high frequency, which cause the difference in variation of peak displacement value.

Effect of fine structure and pore volume in the Marimo-like carbon cathode material on the oxygen reduction reaction for the polymer electrolyte fuel cell

We measured the rotating ring-disk electrode (RRDE) voltammetry curves of a Pt catalyst supported on Marimo-like carbon (MC) to clarify the effect of carbon nanofilaments (CNFs) morphology and fine structures consisting of MC cathode material on the oxygen reduction reaction (ORR) activity for Polymer electrolyte fuel cells. The specific surface area and pore volume of MCs are influenced by their morphology and fine structures. MCs grown with Ni–Cu bimetal catalyst (represented as Ni80Cu20MC), having an octopus-like morphology, yielded four times larger total pore volume than that measured from the MC grown with Ni catalyst (Ni100MC). In the case of Ni80Cu20MC, coin-stacked graphenes perpendicular to the filament axis formed CNFs. Ni100MC consists of cup-stacked CNFs. The difference in the graphene stacked fine structure resulted in a different number of graphene edges covering the CNF surface; however, both supported Pt particle sizes and their distributions were similar. Linear sweep voltammetry with a RRDE revealed that the Pt/Ni80Cu20MC ORR onset potential was higher than that observed from the Pt/Ni100MC. This value is suggested to be correlates with the ORR activity. The origin of the ORR difference was discussed on the basis of the structural difference in the MCs.

Numerical Simulation Study of the Effect of Fine View Pore Structure on Rock Burst

With the gradual shift of coal mining to deeper levels in recent years, rock burst has become one of the primary dynamic hazards faced in deep mining. It has been shown that the pore structure in rocks affects the mechanical properties, but the relationship with the rock burst phenomenon still needs to be clarified. In this paper, we investigated the causes and effects of pore structure on impact mechanical properties using RFPA2D numerical simulation software, established several numerical models with different porosities and pore diameters, and analyzed the stress-strain curves, the relationships between porosity and pore diameter and each the bursting liability indices of the coal rock body were elaborated, and the fitting equations in the range of porosity (0%~10%) and pore diameter (0.25~2.0 mm) were obtained. The results showed that the increase in porosity and pore diameter effectively attenuated the bursting ability of coal rocks, which has some reference significance for the study of early warning and prevention of rock burst phenomenon.

The parallel-transported (quasi)-diabatic basis.

This article concerns the use of parallel transport to create a diabatic basis. The advantages of the parallel-transported basis include the facility with which Taylor series expansions can be carried out in the neighborhood of a point or a manifold such as a seam (the locus of degeneracies of the electronic Hamiltonian), and the close relationship between the derivative couplings and the curvature in this basis. These are important for analytic treatments of the nuclear Schrödinger equation in the neighborhood of degeneracies. The parallel-transported basis bears a close relationship to the singular-value basis; in this article, both are expanded in power series about a reference point and are shown to agree through second order but not beyond. Taylor series expansions are effected through the projection operator, whose expansion does not involve energy denominators or any type of singularity and in terms of which both the singular-value basis and the parallel-transported basis can be expressed. The parallel-transported basis is a version of Poincaré gauge, well known in electromagnetism, which provides a relationship between the derivative couplings and the curvature and which, along with a formula due to Mead, affords an efficient method for calculating Taylor series of the basis states and the derivative couplings. The case in which fine structure effects are included in the electronic Hamiltonian is covered.

Influence of Fine Structures on Gyrosynchrotron Emission of Flare Loops Modulated by Sausage Modes

Sausage modes are a leading mechanism for interpreting short-period quasi-periodic pulsations (QPPs) of solar flares. Forward modeling their radio emission is crucial for identifying sausage modes observationally and for understanding their connections with QPPs. Using the numerical outputs from three-dimensional magnetohydrodynamic simulations, we forward model the gyrosynchrotron emission of flare loops modulated by sausage modes and examine the influence of fine structures of loops. The temporal evolution of the emission intensity is analyzed for an oblique line of sight crossing the loop center. We find that the low- and high-frequency intensities oscillate in phase in the periods of sausage modes for models with or without fine structures. For low-frequency emissions where the optically thick regime arises, the modulation magnitude of the intensity is dramatically reduced by the fine structures at some viewing angles. On the contrary, for high-frequency emissions where the optically thin regime holds, the effects of fine structures or the viewing angle are marginal. Our results show that the periodic intensity variations of sausage modes are not wiped out by fine structures, and that sausage modes remain a promising candidate mechanism for QPPs, even when the flare loops are fine-structured.

Rice noodle quality is structurally driven by the synergistic effect between amylose chain length and amylopectin unit-chain ratio

Chewiness, slipperiness, and rapid rehydration are satisfactory qualities for rice noodles. These qualities are dependent on rice starch structure. However, the synergistic effect of fine structure of amylose (AM) and amylopectin (AP) on rice noodle quality remains unclear. In this work, six rice varieties, three from early indica and three from late indica, with similar amylose content for each pair were analyzed to assess the synergistic effects between AM and AP fine structures. The results showed that the combination of amylose long-chains and a low amylopectin unit-chain (APC) ratio favored the maintenance of relatively intact starch granules, resulting in a higher die expansion ratio and improvement of the mechanical properties of rice noodles (Hardness varied from 403 g to 1627 g). Meanwhile, higher die expansion was associated with a larger rehydration ratio. These results suggest that the synergistic effect between AM and AP fine structures significantly affects rice noodles' quality.

Combined effects of starch fine molecular structures and water content on starch digestibility of cooked white rice

Although the starch digestibility of cooked white rice has been investigated with regard to its relation to starch structure, it is not yet clear how starch molecular structure and water content affect its digestion rate. To investigate this, the in vitro starch digestibility and molecular structure of 10 rice varieties with a range of rice-to-water cooking ratios were investigated. As expected, starch digestibility varied with different conditions. Typically, a higher amylose content resulted in a lower maximum digestion extent for a given water content. Having relatively more and longer amylopectin intermediate chains caused a slower starch digestion rate, but only with rice-to-water ratios between 1:1 and 1:1.2. These results could prove useful to find combinations of starch fine molecular structures and water contents to produce cooked rice with low glycemic index.

Effect of Fine Grain Structure and Nano Oxide Dispersoids on Improved Strength and Ductility of Iron Aluminide Based Intermetallics

Effect of Fine Grain Structure and Nano Oxide Dispersoids on Improved Strength and Ductility of Iron Aluminide Based Intermetallics

Combined effects of starch fine molecular structures and storage temperatures on long-term rice amylopectin retrogradation property

Though the retrogradation property as affected by starch fine molecular structures has been widely investigated, it remains largely unexplored how concurrent starch structures and storage conditions e.g. temperature tailor the starch retrogradation property. The amylopectin long-term retrogradation for 8 different rice starches with a broad range of amylose content was thus investigated under different storage temperatures. Results showed that gelatinized starch stored at −20 °C generally had a narrower melting temperature range from differential scanning calorimetry, while larger cells and thicker cell walls in the gel matrix than that stored at 4 °C. Different linear correlations were found between starch fine molecular structures and amylopectin retrogradation parameters when starch was stored under different temperatures. For example, the melting enthalpy of retrograded starch double helices was negatively correlated with the amount of amylose intermediate chains at 4 °C, while positively correlated with the relative length of amylopectin short chains at −20 °C. Under both temperatures, rice starch R250 had the highest retrogradation enthalpy. These results could help the rice industry improve both the nutritional and textural attributes of cooked rice by selecting starch with desirable molecular structures and optimizing the storage conditions for rice after cooking.

The underlying starch structures of rice grains with different digestibilities but similarly high amylose contents

Six rice cultivars with similarly high amylose contents but significant differences in resistant starch (RS) contents were employed to investigate factors affecting rice starch digestibility. Results of scanning electron microscopy, differential scanning calorimetry, and X-ray diffraction analyses revealed that the enzymolysis resistance and high gelatinization temperature (GT) of the starch granules were the main reasons for the different starch digestibilities. Furthermore, starch fine structure analysis showed that RS content has a positive correlation with intermediate chain amylopectin (DP 13–24) content and a negative correlation with short chain amylopectin (DP 6–12) content. Moreover, under normal cooking conditions, some starch granules within the endosperm do not gelatinize completely due to the high GT of the starch, leading to a lower starch digestibility. Overall, this work provides useful information for understanding the effects of starch fine structure as well as GT on starch digestibility.

The effects of molecular fine structure on rice starch granule gelatinization dynamics as investigated by in situ small-angle X-ray scattering

Dynamic changes of rice starch granules selected for different amylose contents were analyzed in excess water while heated in-situ in a small-angle X-ray scattering (SAXS) instrument. Normal rice starch (NS) and rice starch with high amylopectin (HAP) and high amylose (HAM) were used as models. A 1D linear correlation function and a combination power-law and Gaussian function were used to extract the starch lamellar structure parameters and the fractal dimension, ordering and distribution of starch lamellae from SAXS data. For the resulting starch paste/gels, a model of two-correlation length was fitted to afford the correlation length (ξ) for the paste/gel system. The results showed that HAM exhibited higher long period (LP) and thickness of the crystalline layers (dc) values than HAP and NS. However, HAP showed the highest ordering lamellar structure. HAP granules were more thermostable than the amylose containing starches. For the gelatinized starches, HAM showed the highest correlation length values but these notably decreased with increasing temperature indicating strong chain segment interaction. This research reveals essential structural changes in lamellae of rice starch granules and rice starch gel structure, which provides potentially useful in the working of starch-based foods and materials.

Microscopic calculation of fission product yields with particle-number projection

Fission fragments' charge and mass distribution is an important input to applications ranging from basic science to energy production or nuclear non-proliferation. In simulations of nucleosynthesis or calculations of superheavy elements, these quantities must be computed from models, as they are needed in nuclei where no experimental information is available. Until now, standard techniques to estimate these distributions were not capable of accounting for fine-structure effects, such as the odd-even staggering of the charge distributions. In this work, we combine a fully-microscopic collective model of fission dynamics with a recent extension of the particle number projection formalism to provide the highest-fidelity prediction of the primary fission fragment distributions for the neutron-induced fission of $^{235}$U and $^{239}$Pu. We show that particle number projection is an essential ingredient to reproduce odd-even staggering in the charge yields and benchmark the performance of various empirical probability laws that could simulate its effect. This new approach also enables for the first time the realistic determination of two-dimensional isotopic yields within nuclear density functional theory.

Inelastic processes in copper–hydrogen collisions including fine-structure effects

Abstract Inelastic processes in low-energy Cu + H and Cu+ + H− collisions, 306 partial processes in total, are investigated taking fine-structure effects into account. We use the asymptotic approach to model the adiabatic potentials and adapt a recently proposed method to include the copper fine structure. The nuclear dynamics is performed by the multichannel analytical approach and the Landau–Zener model. The rate coefficients are calculated for the temperature range of 1000–10 000 K. The largest rate coefficient is obtained for the mutual neutralization process Cu+ + H− → Cu(3d105s 2S1/2) + H with a value of $3.81 \times 10^{-8}\, {\rm cm}^3\,{\rm s^{-1}}$ at a temperature of 6000 K . It is shown that the practice to redistribute LS-coupling rate coefficients among fine-structure sublevels can give rates that deviate significantly from those calculated in the JJ-coupling scheme, that is with account for the fine-structure effects.