Fiber-like Structures Research Articles

İskenderun Körfezi'ndeki İstilacı Diadema setosum'un Kabuk, Diken ve Aristoteles Fenerlerinin Karakterizasyonu

The invasive sea urchin Aristotle’s lanterns, shell and spines describe as biological materials. In order to confirm this suggestion, the physical and chemical properties of Aristotle lantern, shell and spine of the invasive Diadema setosum distributed in the Iskenderun Bay were explained for the first time in this study. This species was prepared for the Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS) and scanning electron microscope (SEM) evaluation of Aristotle’s lantern, shell and spine. The results showed that the shell, spine and Aristotle’s lantern are composed of rough, microporous, multilayered, rough and fiber-like structures. According to XRD results, Aristotle’s lantern, shell and spine were found to be similar to calcite. As a result, the shell, spine and Aristotle’s lantern of D. setosum are qualified biological materials that can be used in many areas such as biosorption, biocatalyst, medicine, biomedical applications and lime welding.

Irradiation-enhanced superficial modification and evolution of mechanical behavior in TaTiNbZr refractory high entropy alloy films exposed to low energy helium plasma

In this work, TaTiNbZr refractory high entropy alloy (RHEA) films constructed with nano-crystalline and amorphous composite structures were irradiated by helium (He) plasma with a fixed flux of 5 × 1022 m−2·s−1 under bias-voltage driven plasma energy (0–70 eV) to systematically explore the evolution of morphological modification and mechanical properties. The results indicated that the RHEA exhibited composite structures after He plasma irradiation, and the irradiation-enhanced surface blisters were strongly dependent on He plasma energy. After exposure to He plasma, the size and density of blisters on the surface of RHEA films gradually increased with the enhancement of plasma energy, these blisters originated from the formation of bulges underneath the surface which were induced by the large-sized bubbles. Some blister bursts were initiated at a critical energy of 50 eV (irradiation temperature was 600 K). Non-obvious superficial sputtering can be observed for the RHEA films irradiated at energy less than 50 eV. At the He plasma energy of 70 eV, cracks and abundant blister exfoliation were produced on the RHEA surface due to the synergistic effect of enhanced energy and irradiation temperature (650 K). Surface sputtering and the thermal diffusion-driven mass flow were induced by He plasma due to the sputtering threshold energies in Ti and Zr elements than that of Ta and Nb elements, which were responsible for the growth of fiber-like structures on the surface of RHEA film as the energy was fixed at 70 eV. Moreover, the maximum hardening ratio of 21.4% was revealed from the TaTiNbZr RHEA nano-film irradiated at plasma energy of 50 eV, the role of plasma energy on the evolution of mechanical properties, and the corresponding mechanisms in response to irradiation damage were also discussed in detail.

Unraveling mitotic chromosome structure using optical tweezers.

During mitosis, vertebrate chromosomes compact into X-shapes that are approximately four orders of magnitude shorter than the contour length of the DNA-molecule they consist of. Visualizing the internal structure of these chromosomes is difficult because of their high compaction, though some light has been shed on this problem using (super-resolution) fluorescence microscopy and Hi-C experiments. We developed an optical tweezers method to manipulate mitotic chromosomes and ‘unravel’ them starting from the telomeres, in a way reminiscent of unraveling a woolen sweater by pulling on a thread. The DNA-threads that are pulled from the chromosome are coated by different proteins that are involved in mitotic chromosome architecture (histones, condensins, topoisomerases). Unraveling the chromosome in this way allows us to image its contents without running into problems with the limited resolution of light microscopy, and without resorting to harsh treatments like chromosome fixation. Using immunostaining, we label several different proteins on chromosome threads, and like so, determine their distribution along the chromosomal DNA. While imaging, we measure the force exerted on the chromosome and thread by our optical tweezers. The well-defined overstretching reaction of double-stranded DNA, which occurs at ∼65pN, helps us to determine the number of parallel DNA strands in the unraveled DNA-thread. These DNA-threads show a wide range of thicknesses, with on one end of the spectrum sturdy fiber-like chromatin structures, and on the other end, fragile singular DNA strands. Imaging chromosomal proteins on both these structures will help elucidate the internal structure of mitotic chromosomes. Furthermore, observing the force-extension behavior while unravelling the chromosome gives insight in the folding structure of chromatin in mitotic chromosomes.

Magnetic Systems for Regenerative Medicine

Magnetic Systems for Regenerative Medicine

Quantification methodologies on organization and morphology features of fiber-like structures: A review

Among all the structural formations, fiber-like structure is one of the most common modalities in organisms that undertake essential functions. Alterations in spatial organization of fibrous structures can reflect information of physiological and pathological activities, which is of significance in both researches and clinical applications. Hence, the quantification of subtle changes in fiber-like structures is potentially meaningful in studying structure-function relationships, disease progression, carcinoma staging and engineered tissue remodeling. In this study, we examined a wide range of methodologies that quantify organizational and morphological features of fibrous structures, including orientation, alignment, waviness and thickness. Each method was demonstrated with specific applications. Finally, perspectives of future quantification analysis techniques were explored.

DEVELOPMENT OF BIGELS CONTAINING ANTIFUNGAL AGENT FOR VAGINAL INFECTION

Objective: Bigels are unique semi-solid preparations that have piqued the focus of numerous scientists owing to their significant advantages over ordinary gels. The purpose of this study was to develop and characterize innovative Bigels for applications in drug delivery by combining Hydroxypropyl methylcellulose hydrogel and sorbitan monostearate, oils like coconut and olive-based organogel. The existence of both aqueous and oil phases as bigel was revealed by microscopy. Methods: Hydrogels and organogels were prepared separately, and bigels were formed by combining hydrogel and organogel in a predetermined ratio. They were then analyzed employing various physicochemical tests i. e in vitro drug release, microscopy, and other techniques. Microscopy, viscosity measurement, mechanical analysis, and differential scanning calorimetry were used to examine the bigel's microstructures and physicochemical properties. Results: Tube inversion tests reveal that the bigel doesn’t flow under its own weight till 167 min. The microscopy suggested that the gels exhibited fiber-like structures due to the trapping of the organogel inside hydrogel molecules; this entrapment was demonstrated to be uniformly accomplished, resulting in formulation stability, and the DSC study reveals that the terbinafine is not decomposed also after formulating in bigel, and the terbinafine bigel was also found to be stable. The drug-loaded gels demonstrated effective antibacterial activity against Candida species. The formulated bigel shows initial release in 2 h and slowly release later in 4 h. The formed bigel is found to be stable after 3 mo with a pH range of 7.07±0.04, showing good spreadability and drug content was 99.99±0.75. Conclusion: Terbinafine, the drug of preference for the treatment of bacterial vaginosis, demonstrated diffusion-mediated drug release when placed into bigels. In general, the produced bigels might be employed as delivery vehicles for drugs delivered vaginally.

On the Interfacial Behavior of Catenated Poly(l-lactide) at the Air–Water Interface

Interfacial properties of polymeric materials are significantly influenced by their architectural structures and spatial features, while such a study of topologically interesting macromolecules is rarely reported. In this work, we reported, for the first time, the interfacial behavior of catenated poly(l-lactide) (C-PLA) at the air-water interface and compared it with its linear analogue (L-PLA). The isotherms of surface pressure-area per repeating unit showed significant interfacial behavioral differences between the two polymers with different topologies. Isobaric creep experiments and compression-expansion cycles also showed that C-PLA demonstrated higher stability at the air-water interface. Interestingly, when the films at different surface pressures were transferred via the Langmuir-Blodgett method, successive atomic force microscopy imaging displayed distinct nanomorphologies, in which the surface of C-PLA exhibited nanofibrous structures, while that of the L-PLA revealed a smoother topology with less fiber-like structures.

Thin-Film Morphology and Optical Properties of Photoisomerizable Donor-Acceptor Oligothiophenes.

It was recently reported that the most popular electron-accepting units introduced to π-conjugated oligomers studied for organic photovoltaic applications are susceptible to unwanted and even destructive photochemical reactions. The consequences of Z/E photoisomerization of the popular 2-(1,1-dicyanomethylene)rhodanine (RCN) unit on the optical and morphological properties of a homologous series of RCN-functionalized oligothiophenes are studied here. Oligomers consisting of one, two, or three thiophene units were studied as pure Z isomers and with E isomer compositions of 25, 53, and 45%, respectively, for Z/E mixtures. Solutions of Z isomers and Z/E mixtures were characterized by UV-vis and photoluminescence spectroscopy, wherein changes to optical properties were evaluated on the basis of E isomer content. X-ray diffraction of thin-film Z/E mixtures reveals crystalline domains of both Z and E forms after thermal annealing for mono- and bithiophene oligomers, with greater interplanar spacing for E crystalline domains than the Z counterparts along the substrate normal direction. The surface morphology viewed by atomic force microscopy also shows fiberlike structures for the E form with a much larger aspect ratio than for the Z domains in the bithiophene oligomer. Optical characterization reveals drastic changes in the solid state upon introduction of the E form for the mono- and bithiophene derivatives, whereas subtle consequences are noted for the terthiophene analogue. Most notably, a 132 nm redshift in maximum absorption occurs for the bithiophene oligomer films containing 53% E isomer compared to the pure Z counterpart. Finally, although solid-state photoisomerization experiments find no evidence of Z → E isomerization in polycrystalline Z films, E → Z isomerization is observed and becomes more restrictive in films with higher crystallinity (i.e., after thermal annealing). This structure-property study, which elucidates the consequences of the RCN configuration on solid-state packing and optical properties, is expected to guide the development of more efficient and stable organic optoelectronic devices.

Ditetradecyldiphenylmethane- 4,4-dicarbamate supramolecular gelator: Synthesis, characterization and Oil trapping

In the present research work, supramolecular organo oil gelator was synthesized using diphenylmethane diisocyanate (DMI) and 1-Tetradecanol for the sorption of oil from oil contaminated soil/water mixture. The prepared gelator was characterized using FTIR, mass spectral techniques and SEM analysis. The FTIR and mass spectra assured the formation of oil gelator. Further, SEM analysis showed porous, fiber-like structures. In mechanism, it was proposed that the organo oil gel leads to self-assembly and further entanglements forming the fibres which finally help in oil uptake/trapping. The maximum uptake of the oil was around 50% initially and it was further increased to 92% using gasoline as the co-congealed solvent. Interestingly, the complete gelation of the oil from oil water emulsion was accomplished inside 20 min of application with good oil recovery. This research work confirmed that the oil removal by organo oil gelator could be employed for treating oil contaminated soil/water mixture.

Do Carbon Nanotubes and Asbestos Fibers Exhibit Common Toxicity Mechanisms?

During the last two decades several nanoscale materials were engineered for industrial and medical applications. Among them carbon nanotubes (CNTs) are the most exploited nanomaterials with global production of around 1000 tons/year. Besides several commercial benefits of CNTs, the fiber-like structures and their bio-persistency in lung tissues raise serious concerns about the possible adverse human health effects resembling those of asbestos fibers. In this review, we present a comparative analysis between CNTs and asbestos fibers using the following four parameters: (1) fibrous needle-like shape, (2) bio-persistent nature, (3) high surface to volume ratio and (4) capacity to adsorb toxicants/pollutants on the surface. We also compare mechanisms underlying the toxicity caused by certain diameters and lengths of CNTs and asbestos fibers using downstream pathways associated with altered gene expression data from both asbestos and CNT exposure. Our results suggest that indeed certain types of CNTs are emulating asbestos fiber as far as associated toxicity is concerned.

Exploring reflectance confocal microscopy as a non-invasive diagnostic tool for genital lichen sclerosus.

The diagnosis of genital lichen sclerosus (LS) is often confirmed by obtaining a skin biopsy, which can lead to unwanted complications and is uncomfortable in the sensitive genital area. Thus, there is a need of finding novel, non-invasive techniques that can rapidly and accurately diagnose LS. The present study investigated the potential for reflectance confocal microscopy (RCM) to diagnose LS compared with healthy penile skin and other common penile skin disorders in males. A total of 30 male patients, including patients with LS, nonspecific balanoposthitis, plasma cell balanitis and psoriasis, and healthy individuals were included and were subject to non-invasive RCM investigation. Prominent fiber-like structures, representing hyaline sclerosis, were observed in the RCM images for almost half of the patients. Differences between healthy penile skin and LS were confirmed by identifying the edged papillae on healthy skin and their absence or obscureness in patients with LS. Notably, RCM could detect the atypical honeycomb pattern referring to dysplasia in 1 patient with LS with penile intraepithelial neoplasia. In conclusion, the present study demonstrated that RCM can detect sclerosis in penile LS. RCM can potentially become a valuable tool for monitoring patients with LS for dysplasia providing a useful non-invasive diagnostic tool for genital disorders.

Adaptive Anisotropic Morphological Filtering Based on Co-Circularity of Local Orientations

The algorithm presented in this paper is an application of a general framework for morphological processing of signals on weighted graphs. Here we apply it to images by defining what we call a co-circularity graph. In this graph, the vertices are the pixels and the weighted edges depend on a consistency criterion (co-circularity) between local orientations estimated from the structure tensors. This graph induces anisotropic adaptive morphological operators which are related both to anisotropic diffusion in images and path optimality in graphs. We present several applications such as the enhancement of fiber-like structures, completion of interrupted edges and the regularization of grayscale images. We also discuss the parameters setting depending on the application.

Magnetic Nanoparticle-Mediated Orientation of Collagen Hydrogels for Engineering of Tendon-Mimetic Constructs.

Despite the high incidence of tendon injuries worldwide, an optimal treatment strategy has yet to be defined. A key challenge for tendon repair is the alignment of the repaired matrix into orientations which provide maximal mechanical strength. Using oriented implants for tissue growth combined with either exogenous or endogenous stem cells may provide a solution. Previous research has shown how oriented fiber-like structures within 3D scaffolds can provide a framework for organized extracellular matrix deposition. In this article, we present our data on the remote magnetic alignment of collagen hydrogels which facilitates long-term collagen orientation. Magnetic nanoparticles (MNPs) at varying concentrations can be contained within collagen hydrogels. Our data show how, in response to the magnetic field lines, MNPs align and form string-like structures orientating at 90 degrees from the applied magnetic field from our device. This can be visualized by light and fluorescence microscopy, and it persists for 21 days post-application of the magnetic field. Confocal microscopy demonstrates the anisotropic macroscale structure of MNP-laden collagen gels subjected to a magnetic field, compared to gels without MNP dosing. Matrix fibrillation was compared between non- and biofunctionalized MNP hydrogels, and different gels dosed with varying MNP concentrations. Human adipose stem cells (hASCs) seeded within the magnetically aligned gels were observed to align in parallel to MNP and collagen orientation 7 days post-application of the magnetic field. hASCs seeded in isotropic gels were randomly organized. Tenocyte-likeness of the cells 7 days post-seeding in collagen I scaffolds was confirmed by the positive expression of tenomodulin and scleraxis proteins. To summarize, we have developed a convenient, non-invasive protocol to control the collagen I hydrogel architecture. Through the presence or absence of MNP dosing and a magnetic field, collagen can be remotely aligned or randomly organized, respectively, in situ. Tendon-like cells were observed to organize in parallel to unidirectionally aligned collagen fibers and polydirectionally in non-aligned collagen constructs. In this way, we were able to engineer the constructs emulating a physiologically and pathologically relevant tendon niche. This can be considered as an innovative approach particularly useful in tissue engineering or organ-on-a-chip applications for remotely controlling collagen matrix organization to recapitulate the native tendon.

Production of Plant-Based Seafood: Scallop Analogs Formed by Enzymatic Gelation of Pea Protein-Pectin Mixtures.

This study investigated the possibility of using a phase separation, mixing, and enzymatic gelation approach to construct seafood analogs from plant protein-polysaccharide mixtures with properties mimicking real seafood. Heat-denatured pea protein (10%, w/w) and pectin (0–1%, w/w) were mixed to produce phase separated biopolymer blends. These blends were then subjected to mild shearing (350 rpm) to obtain fiber-like structures, which were then placed in molds and set by gelling the pea proteins using transglutaminase (2%, w/w). The appearance, texture, and cooking properties of the resulting scallop analogs were characterized and compared to those of real scallop. The presence of the pectin promoted the formation of a honeycomb structure in the scallop analogs, and microscopic orientation of the proteins was observed in the plane parallel to the applied shear flow. Lower pectin concentrations (0.5%, w/w) led to stronger gels with better water holding capacity than higher ones (1.0%, w/w). The appearance and texture of the plant-based scallop analogs were like those of real scallop after grilling, indicating the potential of using this soft matter physics approach to create plant-based seafood analogs. One of the main advantages of this method is that it does not require any expensive dedicated equipment, such as an extruder or shear cell technology, which may increase its commercial viability.

A gel lattice alters the phase state of a solvent.

Some low-molecular-weight substances are able to self-assemble into fiber-like structures (strings) to form gels. One of the examples of such substances is trifluoroacetylated alpha-aminoalcohols (TFAAAs) able to gelate in many organic solvents. Here we report the formation and describe the properties of a layer of an altered solvent covering the strings' surface. The altered solvent layer has a different refractive index and melts at a temperature about several degrees lower than that of the bulk solvent. Moreover, the bulk solvent's melting temperature was also decreased by values far beyond the one expected according to Raoult's law. Based on the Gibbs-Thomson equation it is possible to derive the thickness of the special layer as well as the average gel lattice parameters, which were very stable across the variety of systems investigated.

On photostability of acrylate and polymethyl methacrylate planar fiber-like structures with CUMARIN 7, 47, 120; POPOP; NOL8 luminophores for UV information systems

Studies of photostability of planar fiber-like structures in the form of films 600-800 μm thick made of high-purity polymethyl methacrylate (PMMA) and acrylic resin, in which CUMARIN 7, 47, 120; POPOP, NOL8 luminophores were introduced, were carried out under long-term ultraviolet (UV) irradiation. NOL12 (KNL12) luminophore was in polymer fibers produced by "Engineering Centre for Polymer Optical Fibers" LLC. PMMA fiber-optic guides were attached to the ends of the films, from the output of these guides the luminescence radiation power was measured as a function of the UV irradiation power and time. The prospects of applying Cumarin-type luminophores for using planar fiber-like structures in UV information systems as receiving antennas for optical telecommunications and optical sensors for monitoring physical fields are shown. Keywords: photostability, planar fiber-like structures, luminophores, information systems.

Characterization of the Kisspeptin and GnRH expression in the hypothalamus of the male and female taiep rat, an animal model of demyelination.

Reproductive alterations have been reported in patients with demyelinating diseases, these alterations can lead to infertility. In the hypothalamus we can find two neuronal types that regulate reproductive function; kisspeptidergic and GnHergic neurons. At the present moment, the relation between demyelination and reproductive alterations it is yet unknown; in order to elucidate this relation, we used the taiep rat, an animal that presents demyelination of the central nervous system and that also shows reproductive issues. We characterized the immunofluorescent expression of kisspeptin and GnRH in the hypothalamus of the male and female taiep rats using Sprague-Dawley rats as control. We obtained the brains of the females during oestrous and adult males; the brains were cut at 10mm. Performed immunofluorescence of kisspeptin and GnRH (bs-0749r-cy5, bs-10369R-A488; Bioss Antibodies) and analysed the intensity of the fluorescence in the hypothalamus using the software ImageJ1.50i. Fluorescence is concentrated in fiber-like structures with neuron shape. An increment in the intensity of the fluorescence of kisspeptin was observed in said structures in male taiep rats compared with SD (0.37±0.02 vs 0.28±0.01, p< 0.001). Female taiep rats during oestrus showed a decrease in the intensity of the fluorescence of kisspeptin structures compared with SD (0.44±0.02 vs 0.57±0.03, p< 0.001). We could not observe any significant changes in the expression of GnRH fibers in the hypothalamus of the taiep rat compared with SD. Demyelination in the taiep rat affects kisspeptin expression at hypothalamic level, but this does not affect the expression of GnRH in either males or females, this effect is probably related with the availability of receptors in the GnRHergic neuron, we will evaluate this in the future. The decrease in kisspeptin expression in the female taiep rat, could be caused by previously reported low concentrations of oestrogen, given that it is capable of stimulating kisspeptin expression.

Experimental comparison of acoustic backscattered field from a single fiber and media with pseudo-aligned fibers in longitudinal and transverse planes

Acoustic backscatter spectrum analyses of soft tissues are being developed to provide quantitative information beyond that offered by B-mode images. Common assumptions used in some approaches are that the medium is homogeneous, isotropic, and produces diffuse scattering conditions. However, in some soft tissues, the presence of fiber-like structures causes the acoustic backscatter to be anisotropic. In this work, we compare the backscattered fields produced by a single fiber, a phantom containing many pseudo-aligned fibers, and biceps muscle. Measurements were performed with single-element immersion transducers using a laboratory benchtop pulse-echo setup, and different linear array transducers on a Siemens Acuson S3000 scanner. The phantom and muscle were imaged in longitudinal and transverse planes to study the effect of fiber orientation on the backscattered field. The results showed that the normalized backscattered power is different in longitudinal and transverse planes. This can result from differences in the sonicated portion of the fibers when varying their orientation with respect to the 3D diffraction pattern. Future work will further study this phenomenon with single fibers and transducers with different focal configurations, and investigate the use of the point-wise signal-to-noise ratio and the generalized spectrum to detect the presence of coherent scattering conditions.

Structural Plasticity of LL-37 Indicates Elaborate Functional Adaptation Mechanisms to Bacterial Target Structures.

The human cathelicidin LL-37 is a multifunctional peptide of the human innate immune system. Among the various functions of LL-37, its antimicrobial activity is important in controlling the microorganisms of the human body. The target molecules of LL-37 in bacteria include membrane lipids, lipopolysaccharides (LPS), lipoteichoic acid (LTA), proteins, DNA and RNA. In this mini-review, we summarize the entity of LL-37 structural data determined over the last 15 years and specifically discuss features implicated in the interactions with lipid-like molecules. For this purpose, we discuss partial and full-length structures of LL-37 determined in the presence of membrane-mimicking detergents. This constantly growing structural database is now composed of monomers, dimers, tetramers, and fiber-like structures. The diversity of these structures underlines an unexpected plasticity and highlights the conformational and oligomeric adaptability of LL-37 necessary to target different molecular scaffolds. The recent co-crystal structures of LL-37 in complex with detergents are particularly useful to understand how these molecules mimic lipids and LPS to induce oligomerization and fibrillation. Defined detergent binding sites provide deep insights into a new class of peptide scaffolds, widening our view on the fascinating world of the LL-37 structural factotum. Together, the new structures in their evolutionary context allow for the assignment of functionally conserved residues in oligomerization and target interactions. Conserved phenylalanine and arginine residues primarily mediate those interactions with lipids and LPS. The interactions with macromolecules such as proteins or DNA remain largely unexplored and open a field for future studies aimed at structures of LL-37 complexes. These complexes will then allow for the structure-based rational design of LL-37-derived peptides with improved antibiotic properties.

Epoxy Nanocomposites with Carbon Nanotubes Produced by Floating Catalyst CVD.

Epoxy nanocomposites with float catalysis-produced CNT felt as a filler were prepared. Parameters such as the curing process, glass transition of epoxynanocomposites, structure and morphology of CNT felt, initial epoxy composition, and epoxy nanocomposites were investigated. The influence of CNT felt on curing process in epoxy nanocomposites with different amounts of curing agent was determined. An exothermic reaction between the curing agent and the surface of CNTs was established. It was found that the structure of epoxy nanocomposites has a high degree of heterogeneity: the presence of fiber-like structures and individualized CNTs is observed together with the regions that are typical for CNTs that are fabricated via a catalytic chemical vapor deposition (CVD). Based on the studies performed, it is possible to predict the production of epoxy nanocomposites with outstanding mechanical and thermophysical properties. In particular, the uncured compositions already obtained in this work can be used for the manufacture of electrically conductive glass and carbon fiber reinforced plastics and functional coatings.