Low-angle x-ray fine structure investigation of tussah protein fiber

Low-angle x-ray methods have been used to evaluate some macromolecular parameters of the scattering particles in tussah, a silk fiber. A low-angle Kratky camera of recent design has been used for the experimental measurements of the scattering intensities. The sample under investigation is taken as a densely packed colloidal system belonging to general micelle system and the well known theories of Kratky and Kratky and Porod have been utilized. The parameters determined are specific inner surface of the dispersed phase (O/V), transverse lengths like the length of inhomogeneity (l_r) and the length of coherence (l_c), and the air fraction of the scattering particles in tussah fiber; these were found to be 7.084 × 10^?6 Å^?1, 100.6 Å, 367.7 Å, and 0.02%, respectively.     

The investigation of cancerous human bone (osteoclastoma) by small-angle X-ray scattering

Small-angle X-ray scattering methods were applied to provide a pore analysis of cancerous human bone (osteoclastoma). For experimental measurements of the scattering intensities a small-angle Kratky camera, equipped with a counterattachment and a programmable step-scanning device, was used. By applying the theories of Kratky, Porod, Debye, and Bueche, applicable to a densely packed two-phase system belonging to a general micelle system, macromolecular parameters such as specific inner surface, length of coherence, range of inhomogeneity, void percentage, and transversal lengths l?₁ and l?₂ were evaluated and found to be 4.69 × 10^?4 Å^?1, 21.39 Å, 18.01 Å, 0.21%, 18.01 Å and 8.53 × 10³ Å, respectively. A comparison of these parameters with those of pure human bone revealed a macromolecular dissociation in osteoclastoma.     

Correlation between macromolecular parameters and the average breaking strength of agave fibers

The small-angle X-ray scattering method was applied to evaluate macromolecular parameters of Agave fibers (Agave sisalana, A. cantala, A. hybrid, A. elongata, and A. ameniensis). The macromolecular parameters such as specific inner surface, percentage of void, length of coherence, range of inhomogeneity, and transversal lengths were evaluated. The correlation of macromolecular parameters with the average breaking strength of Agave fibers did not lead to a linear relation, however, the specific macromolecular organization in A. sisalana manifested higher breaking strength.     

Low-angle x-ray estimation of macromolecular parameters of the scattering particles in Agave sisalana

Various macromolecular parameters of Agave sisalana (sisal) fiber were investigated by the low-angle x-ray scattering method. The well known Kratky camera of the latest design was utilized for the experimental measurements. The sample studied was a densely packed colloidal system belonging to a general micelle system, and the theories of Kratky and Kratky and Porod were utilized to estimate the parameters. Pore analysis of the substance yields a value for the specific inner surface of the dispersed phase of 0.406 × 10^?1 m²/cm³; the transversal length is the same as the length of inhomogeneity, 107.31 Å, and the length of coherence is 342.21 Å. The air fraction of the scattering particles was found to be 0.01%.     

Small-angle x-ray investigation of a densely packed micelle system in agave hybrid

Small-angle x-ray scattering methods were applied to calculate macromolecular parameters like specific inner surface (O/V), length of coherence (l_c), and the percentage of air present in agave hybrid, treating it as a densely packed colloidal system belonging to a general micelle system. The parameters were equal to O/V = 8.50 × 10^?6 Å^?1, l_c = 150 Å, and the percentage of air = 0.03. The Kratky camera with latest design was used for the experimental measurement. Because the sample agave ybrid is a natural fiber and a highly oriented system that is celluosic in character, the theories of Kratky and Porod have been used to evaluate these parameters.     

Estimation of parameters of the scattering particles in elastoidin by low-angle X-ray methods

Low-angle x-ray scattering methods have been used to evaluate some parameters like specific inner surface of the dispersed phase, transverse lengths, the length of in homogeneity, the length of coherence, and the air-fraction of the scattering particles in Elastoidin. The low-angle Kratky camera of the latest design was used for the experimental measurements. Since the sample under investigation is a densely packed solid polymer, the theories of Kratky and Kratky and Porod have been used to evaluate these parameters.     

Small-angle X-ray scattering of air-dried kangaroo tail tendon

Air-dired kangaroo tail tendon (KTT) is a protein sample similar to collagen and has been investigated by small-angle x-ray scattering treating it as a densely packed colloidal system which belongs to a general micelle system. Pore analysis of the substance yields a specific inner surface of 0.6282 × 10^?5 Å^?1, a range of inhomogeneity of 69.11 Å, a length of coherence of 248.2 Å, and air-fraction percentage of 0.011. A Kratky camera of the latest design has been used for experimental measurements. As the log? vs. logX curve gives a slope of ?3, KTT belongs to a densely packed two-phase system. Here the theory of small-angle scattering by densely packed systems as developed by Porod has been applied to find different physical parameters of KTT.     

Effect of ultrasound on the microstructure of polystyrene in cyclohexane: a synchrotron small-angle X-ray scattering study

Synchrotron small-angle X-ray scattering technique has been used to study the effect of ultrasound on the microstructure of polystyrene (PS) in cyclohexane solutions. The results show that the intramolecular radius of gyration (R _g) decreases with ultrasound, indicating the shrinkage and collapse of PS chains. There is an exponential relationship between R _g and the molecular weight of PS (M _w), and the exponent changes from 0.5 to 0.417, as the ultrasound time is increased. This means that the shape of PS chain changes from random coil to shrunken form. The Kratky plots also confirm the shape transformation of PS chains induced by ultrasound. Moreover, the intermolecular correlation length increases with the ultrasound time, which is indicative of the entanglement of PS chains.     

再生蚕丝的制备及其结构和性能初探

在制备高浓度高分子量蚕丝素蛋白水溶液的基础上, 采用湿法纺丝技术, 在一定条件下纺制出力学性能优于天然蚕(茧)丝的再生蚕丝纤维, 其断裂强度及断裂伸长率分别达到0.5 GPa和20%. 扫描电镜观察结果显示: 初生纤维具有典型的“皮芯”结构, 而纤维内部则为疏松多孔的网状或蜂窝状结构; 经过一定的后拉伸处理后, 纤维的表面变得光滑, 且内部结构也趋于致密. 固体 13C核磁共振及拉曼光谱分析结果表明, 后拉伸及热湿处理均有利于提高纤维内部β-折叠结构的含量, 分子链的规整度和取向性也随之改善, 从而使再生蚕丝纤维的力学性能得到进一步提高.     

甲基丙烯酸双酯改性真丝的热性质

众所周知 ,真丝绸因具有柔和的光泽、细腻的手感、良好的舒适性和保健性而素有“纤维皇后”的美称 .但其极易起毛起皱 ,尤其是湿态下更为严重 ,这大大影响了它的实用价值 .70年代以来 ,人们就开始用化学整理的方法提高和改善真丝绸的各种性能 ,但所用整理剂含有游离甲醛 ,或经其整理后织物会释放对人体有害的甲醛 .随着人们生活水平的提高 ,人们对“绿色纺织品”的需求越来越迫切 ,要求整理向低甲醛、无甲醛方向发展 .近年来 ,人们对用单烯类和环氧化合物对真丝进行改性的研究作了大量的工作[1～ 4] ,这些改性在某种程度上能够改善真丝的性…     

The implication of chemical extraction treatments on the cell wall nanostructure of softwood

Spruce wood was subjected to well-defined extraction treatments with sodium chlorite (NaClO₂) for delignification, as well as with sodium hydroxide (NaOH) at different concentrations for extraction of hemicelluloses. The corresponding changes of the macromolecular polymer assembly were investigated by small-angle X-ray scattering (SAXS). Measurements with Fourier-transform infrared (FTIR) spectroscopy and wide-angle scattering (WAXS) gave qualitative information about the effectiveness of the extraction process, while the scattering experiments provided information about the regularity and typical dimensions of the molecular structures. The scattering data indicated that delignification had only a moderate effect on the structural organisation of the cell wall, while further extraction with NaOH induced considerable nanostructural changes.     

Molecular dimensions and chain conformation in glassy syndiotactic polystyrene

For the first time the small-angle neutron scattering (SANS) from mixtures of protonated and totally deuterated syndiotactic polystyrene (sPS) has been studied. Two amorphous samples with similar molecular weights have been measured at various concentrations of the protonated part. All measurements were performed at room temperature using the scattering equipment of two different laboratories. The molecular weight M_w evaluated from SANS data agreed with those obtained by gel permeation analysis (GPC). In the Kratky representation the scattering contribution due to the contrast scattering shows a plateau behavior up to q = 0.45 Å^?1, where q is magnitude of the scattering vector. This observation is in evident contrast to what is expected from the rotational isomeric state (RIS) model. In addition the characteristic ratios C_∞, derived either from the plateau height or from radii of gyration of the Zimm regime and being in reasonable agreement with each other, show strong deviations from the predictions of the RIS model. © 1994 John Wiley & Sons, Inc.     

Estimation of parameters of the scattering particles in horn keratin by low-angle X-ray scattering

Low-angle x-ray scattering methods have been applied to determine the parameters of the scattering materials in horn keratin. A low-angle camera of Kratky's latest design has been used for the experimental measurements. By treating the substance as a densely packed system, the evaluation of the parameters has been made after theories of Porod and Kratky. Pore analysis of the substance yields a specific inner surface of 4.7 × 10^?1m²/cm³, a heterogeneity distance l_c = 290.2Å and a reduced inhomogeneity length l_r = 99.4Å. The volume of the pores has also been determined approximately.     

Interactions of cartilage extracellular matrix macromolecules

Articular cartilage is a low-friction, load-bearing tissue located at joint surfaces. The extracellular matrix (ECM) of cartilage consists of a fibrous collagen network, which is prestressed by the osmotic swelling pressure exerted by negatively charged proteoglycan (PG) aggregates embedded in the collagen network. The major PG is the bottlebrush-shaped aggrecan, which forms complexes with linear hyaluronic acid (HA) chains. We quantify microscopic and macroscopic changes resulting from self-assembly between aggrecan and HA using a complementary set of physical measurements to determine structure and interactions by combining scattering techniques, including small-angle X-ray scattering, small-angle neutron scattering, and dynamic light scattering with macroscopic osmotic pressure measurements. It is demonstrated that the osmotic pressure that defines the load-bearing ability of cartilage is primarily governed by the main macromolecular components (aggrecan and collagen) of the ECM. Knowledge of the interactions between the macromolecular components of cartilage ECM is essential to understand biological function and to develop successful tissue engineering strategies for cartilage repair. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012     

A novel application of small-angle scattering techniques: Quality assurance testing of virus quantification technology

Small-angle scattering (SAS) techniques, like small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS), were used to measure and thus to validate the accuracy of a novel technology for virus sizing and concentration determination. These studies demonstrate the utility of SAS techniques for use in quality assurance measurements and as novel technology for the physical characterization of viruses.     

Nonspherical assemblies generated from polystyrene-b-poly(L-lysine) polyelectrolyte block copolymers

This report describes the aqueous solution self-assembly of a series of polystyrene(m)-b-poly(L-lysine)n block copolymers (m = 8-10; n = 10-70). The polymers are prepared by ring-opening polymerization of epsilon-benzyloxycarbonyl-L-lysine N-carboxyanhydride using amine terminated polystyrene macroinitiators, followed by removal of the benzyloxycarbonyl side chain protecting groups. The critical micelle concentration of the block copolymers determined using the pyrene probe technique shows a parabolic dependence on peptide block length exhibiting a maximum at n = approximately 20 (m = 8) or n = approximately 60 (m = 10). The shape and size of the aggregates has been studied by dynamic and static light scattering, small-angle neutron scattering (SANS), and analytical ultracentrifugation (AUC). Surprisingly, Holtzer and Kratky analysis of the static light scattering results indicates the presence of nonspherical, presumably cylindrical objects independent of the poly(L-lysine)n block length. This is supported by SANS data, which can be fitted well by assuming cylindrical scattering objects. AUC analysis allows the molecular weight of the aggregates to be estimated as several million g/mol, corresponding to aggregation numbers of several 10s to 100s. These aggregation numbers agree with those that can be estimated from the length and diameter of the cylinders obtained from the scattering results.     

Morphology and tensile property relations of high-strength/high-modulus polyethylene fiber

High-strength/high-modulus polyethylene (PE) fibers have been obtained from linear polymers by melt-spinning the polyethylene followed by hot-drawing the spun filaments. Fibers with different tensile properties were made by changing the extrusion, solidification, and drawing conditions and by use of different types of polyethylene. Potential correlations of fiber strength with morphological parameters such as crystallite dimensions, and crystalline and amorphous orientation were examined. The integrated meridional small-angle x-ray scattering intensity is the only morphological parameter which was found to correlate well with the strength of fibers prepared under different conditions and from different polymer types. Implications with respect to the molecular mechanism of PE fiber drawing are also discussed.     

Surface fractal and structural properties of layered clay minerals monitored by small-angle X-ray scattering and low-temperature nitrogen adsorption experiments

Small-angle X-ray scattering of the clay minerals kaolinite, montmorillonite and illite was studied with a compact Kratky camera. From the scattering function, the correlation length, the Porod constant and the specific surface area were determined. The scattering functions also led to the surface fractal dimension. The pore volume distribution, the adsorption/desorption hysteresis, the specific surface area and the surface fractal dimension of the same samples were also determined by nitrogen adsorption at 77 K.     

The preparation of novel nanofilled polymer composites using poly(l-lactic acid) and protein fibers

In this communication, we present novel nanofilled polymer composites prepared using a poly(l-lactic acid) (PLLA) matrix and amyloid fibers. Amyloid fibers are made from protein sources’ and share many of the same material properties as spider silk, but exist at significantly smaller length scales with diameters of 5–10 nm. This work highlights the potential use of amyloid fibers as nanofillers in the development of renewable polymeric materials with tuneable properties. Improvements in the glass transition temperature (T_g), elongation at break and Young’s modulus was measured, while the yield strength of the new materials was not seriously hampered.