Selüloz ve Soya Proteininin Gama Işınlanmış Solüsyonlarından Hazırlanan Karışım Filmler

Blend solutions of cellulose and soy protein isolate were prepared by utilizing an amine/salt solvent system. The solutions were gamma irradiated before casting blend films that have more stable molecular network than the ones cast from non-irradiated solutions. Due to irradiation, the interactions between the two polymers altered and shifted that were analyzed by infrared spectroscopy. The thermal analysis showed small differences of thermal stability between the films formed from irradiated and non-irradiated solutions. Up to 10 kGy irradiation dose on the solutions, the resulting films exhibited higher elongation at break. Furthermore, their transparency lowered. Despite their transparency, the films absorbed less water indicating the effect of gamma irradiation on the molecular structure.Selüloz ve soya proteini izolatının harman çözeltileri, bir amin/tuz çözücü sistemi kullanılarak hazırlandı. Gama ışınıyla ışınlanan çözeltilerden harman filmlerin oluşturulmuş ve ışınlanmamış filmlerden daha kararlı moleküler ağa sahip oldukları gözlenmiştir. Işınlama bağlı olarak, kızılötesi spektroskopi ile analiz edilen iki polimer arasındaki etkileşimler değişti ve yayıldı. Termal analiz, ışınlanmış ve ışınlanmamış çözeltilerden oluşturulan filmler arasında küçük termal kararlılık farkları gösterdi. 10 kGy ışınlama dozu uygulanan solüsyonlardan elde edilen filmler kopmada daha yüksek uzama göstermiştir. Dahası, filmlerin şeffaflıkları azaldığı gözlendi. Şeffaflıklarındaki değişime rağmen, filmler, gama ışımasının moleküler yapı üzerindeki etkisi dolayısıyla daha az su emdiler

Novel membranes regenerated from blends of cellulose/gluten using ethylenediamine/potassium thiocyanate solvent system

Current industrial methods for dissolution of cellulose in making regenerated cellulose products are relatively expensive, toxic and dangerous and have environmental problems coming with the hazard chemical wastes. To solve these problems, a novel ethylenediamine and potassium thiocyanate (ED/KSCN) solvent system was developed, that is economical, ecofriendly, and highly efficient. The ED/KSCN solvent system was proven to be a suitable solvent for fabricating cellulose (blended with other polymers) membranes. In this study, gluten was used to develop nonporous membranes with cellulose. The method of casting these membranes provided better ones than the former researchers’ techniques. These composite membranes’ physical and mechanical properties were studied by analysis of morphology, viscosity, crystallinity, thermal behaviors, tensile properties and water absorption of membranes. Results showed that membranes are nonporous, uniform, strong, flexible, ecofriendly and renewable. Mechanical and physical properties were influenced by the ratio of cellulose/gluten. By blending 40% gluten, the tensile strength of cellulose membrane dropped to 15.89 MPa from 35.11 MPa. However, its elongation at break increased from 35.3% to 57.02% accordingly. © 2019 Tech Science Press

The impact of tomato fruits containing multi-walled carbon nanotube residues on human intestinal epithelial cell barrier function and intestinal microbiome composition

Carbon nanomaterials (CNMs) can positively regulate seed germination and enhance plant growth. However, clarification of the impact of plant organs containing absorbed CNMs on animal and human health is a critical step of risk assessment for new nano-agro-technology. In this study, we have taken a comprehensive approach to studying the effect tomato fruits derived from plants exposed to multiwalled carbon nanotubes (CNTs) have on gastrointestinal epithelial barrier integrity and their impact on the human commensal intestinal microbiota using an in vitro cell culture and batch human fecal suspension models. The effects of CNTs on selected pure cultures of Salmonella enterica Typhimurium and Lactobacillus acidophilus were also evaluated. This study demonstrated that CNT-containing fruits or the corresponding residual level of pure CNTs (0.001 mu g ml(-1)) was not sufficient to initiate a significant change in transepithelial resistance and on gene expression of the model T-84 human intestinal epithelial cells. However, at 10 mu g ml(-1) concentration CNTs were able to penetrate the cell membrane and change the gene expression profile of exposed cells. Moreover, extracts from CNT-containing fruits had minimal to no effect on human intestinal microbiota as revealed by culture-based analysis and 16S rRNA sequencing

Effects of freeze-thawing cycles on the physical and mechanical properties of basaltic and dolomitic rocks evaluated with a decay function model

Basalts from Çorlu Karatepe and dolomite from Kırklareli subjected to freeze-thawing (F-T) cycles were studied, and the resulting changes were analyzed. The unweathered rocks and those subjected to 50 F-T cycles after every 10 cycles were tested for the water absorption by weight and volume, P-wave velocity, uniaxial compression strength, point load strength index, and Schmidt hardness values under laboratory conditions. In addition, the relationship between physical and mechanical properties was examined after every 10 cycles, and an exponential model was proposed for the mechanical properties. Two model-generated parameters, i.e., the decay constant and half-life value for each mechanical property, were used to evaluate the disintegration rate of the rocks under the cyclical action of F-T. The evaluation suggests that disintegration behavior was not comparable between the two types of rocks. However, the basalt samples had similar mechanical properties, which indicated a high degree of correlation. © 2021, Springer-Verlag GmbH Germany, part of Springer Nature

Aliphatic Polyester Nanofibers Functionalized with Cyclodextrins and Cyclodextrin-Guest Inclusion Complexes

The fabrication of nanofibers by electrospinning has gained popularity in the past two decades; however, only in this decade, have polymeric nanofibers been functionalized using cyclodextrins (CDs) or their inclusion complexes (ICs). By combining electrospinning of polymers with free CDs, nanofibers can be fabricated that are capable of capturing small molecules, such as wound odors or environmental toxins in water and air. Likewise, combining polymers with cyclodextrin-inclusion complexes (CD-ICs), has shown promise in enhancing or controlling the delivery of small molecule guests, by minor tweaking in the technique utilized in fabricating these nanofibers, for example, by forming core–shell or multilayered structures and conventional electrospinning, for controlled and rapid delivery, respectively. In addition to small molecule delivery, the thermomechanical properties of the polymers can be significantly improved, as our group has shown recently, by adding non-stoichiometric inclusion complexes to the polymeric nanofibers. We recently reported and thoroughly characterized the fabrication of polypseudorotaxane (PpR) nanofibers without a polymeric carrier. These PpR nanofibers show unusual rheological and thermomechanical properties, even when the coverage of those polymer chains is relatively sparse (~3%). A key advantage of these PpR nanofibers is the presence of relatively stable hydroxyl groups on the outer surface of the nanofibers, which can subsequently be taken advantage of for bioconjugation, making them suitable for biomedical applications. Although the number of studies in this area is limited, initial results suggest significant potential for bone tissue engineering, and with additional bioconjugation in other areas of tissue engineering. In addition, the behaviors and uses of aliphatic polyester nanofibers functionalized with CDs and CD-ICs are briefly described and summarized. Based on these observations, we attempt to draw conclusions for each of these combinations, and the relationships that exist between their presence and the functional behaviors of their nanofibers

Controlled Assembly Of Lignocellulosic Biomass Components And Properties Of Reformed Materials

Reforming whole lignocellulosic biomass into value-added materials has yet to be achieved mainly due to the infusible nature of biomass and its recalcitrance to dissolve in common organic solvents. Recently, the solubility of biomass in ionic liquids (ILs) has been explored to develop all-lignocellulosic materials; however, efficient dissolution and therefore production of value-added materials with desired mechanical properties remain a challenge. This article presents an approach to producing high-performance lignocellulosic films from hybrid poplar wood. An autohydrolysis step that removes ≤50% of the hemicellulose fraction is performed to enhance biomass solvation in 1-ethyl-3-methyl imidazolium acetate ([C2mim][OAc]). The resulting biomass-IL solution is then cast into free-standing films using different coagulating solvents, yet preserving the polymeric nature of the biomass constituents. Methanol coagulated films exhibit a cocontinuous 3D-network structure with dispersed domains of less than 100 nm. The consolidated films with controllable morphology and structural order demonstrate tensile properties better than those of quasi-isotropic wood. The methods for producing these biomass derivatives have potential for fabricating novel green materials with superior performance from woody and grassy biomass

Carbon nanofibers based carbon–carbon composite fibers

Abstract Textile grade polyacrylonitrile (PAN) was used as a precursor material for carbon fiber preparation. E-beam irradiated polyacrylonitrile grafted carbon nanofibers were dispersed in polyacrylonitrile solution (dissolved in dimethyl formamide). Carbon nanofibers (CNF) infused polyacrylonitrile solution was wet spun on a lab-scale wet-spinning setup to form 50 to 70 µm diameter fibers with 3.2 wt.% CNF-PAN, 6.4 wt.% CNF-PAN, and neat PAN. Precursor fibers were characterized for thermal, mechanical and morphological properties using various techniques. Drawing the precursor fibers further enhanced polymer chain orientation and coalesced the voids, enhancing tensile strength and modulus by more than 150% compared to those of the undrawn fibers. Precursor composite fibers on carbonization showed enhanced strength, compared to that of pristine PAN fibers, by four times and stiffness by 14 times. The carbon–carbon composite fibers were further characterized with SEM/FIB, XRD and tensile strength. The property improvements were dependent on the uniform distribution of carbon nanofibers, and surface modification of carbon nanofibers further enabled their dispersion in the composite fibers. Furthermore, 3.2 wt.% CNFs in PAN fibers showed maximum improvement in properties compared to 6.4 wt.% CNF in PAN fibers, indicating that the property enhancements go through a maximum and then drop off due to challenge in getting uniform distribution of nanofibers

Thermal, mechanical, and topographical evaluation of nonstoichiometric alpha-cyclodextrin/poly(epsilon-caprolactone) pseudorotaxane nucleated poly(epsilon-caprolactone) composite films

Three pseudorotaxanes (PpR) comprised of poly (epsilon-caprolactone) (PCL) and alpha-cyclodextrin (alpha-CD) with varying stoichiometric ratios were synthesized and characterized. Wide-angle X-ray diffraction (WAXD) and thermogravimetric (TGA) analyses provided conclusive evidence for complexation between the guest PCL and host alpha-CD. The as-synthesized and characterized PpRs were used at 10 and 20% concentrations as nucleants to promote the bulk PCL crystallization in composite films. Both WAXD and TGA provided evidence for intact PpR structures in the composite films. Isothermal differential scanning calorimetric (I-DSC) analyses, performed at various crystallization temperatures demonstrated significant differences in the crystallization patterns among the composite films. In addition, I-DSC analyses showed higher Avrami constant values (n) in the PpR-nucleated composite PCL films (n similar to 3), indicating 3-dimensional crystal growth. In the case of neat PCL films, however, lower n values indicated crystal growth in 1-dimensions or 2-dimensions. Moreover, atomic force microscopic analyses showed large crests and pits in PpR-nucleated PCL composites, with irregular morphologies leading to higher surface roughness. To the contrary, the crests and pits were much smaller in the neat PCL films, resulting in lower surface roughness values. Finally, mechanical testing revealed higher tensile strength for PpR-nucleated PCL composites films, demonstrating larger load bearing capabilities. (c) 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018, 56, 1529-1537College of Textiles, North Carolina State University; Department of Science and Technology (DST), IndiaDepartment of Science & Technology (India); State of North Carolina; National Science FoundationNational Science Foundation (NSF) [ECCS-1542015]The authors acknowledge the financial support provided by the College of Textiles, North Carolina State University. I. Matai is thankful to the Department of Science and Technology (DST), India for providing the financial support. This work was performed in part at the Analytical Instrumentation Facility (AIF) at North Carolina State University, which is supported by the State of North Carolina and the National Science Foundation (Award No. ECCS-1542015). The AIF is a member of the North Carolina Research Triangle Nanotechnology Network (RTNN), a site in the National Nanotechnology Coordinated Infrastructure (NNCI)

Thermal, mechanical, and topographical evaluation of nonstoichiometric α‐cyclodextrin/poly(ε‐caprolactone) pseudorotaxane nucleated poly(ε‐caprolactone) composite films

Three pseudorotaxanes (PpR) comprised of poly (epsilon-caprolactone) (PCL) and alpha-cyclodextrin (alpha-CD) with varying stoichiometric ratios were synthesized and characterized. Wide-angle X-ray diffraction (WAXD) and thermogravimetric (TGA) analyses provided conclusive evidence for complexation between the guest PCL and host alpha-CD. The as-synthesized and characterized PpRs were used at 10 and 20% concentrations as nucleants to promote the bulk PCL crystallization in composite films. Both WAXD and TGA provided evidence for intact PpR structures in the composite films. Isothermal differential scanning calorimetric (I-DSC) analyses, performed at various crystallization temperatures demonstrated significant differences in the crystallization patterns among the composite films. In addition, I-DSC analyses showed higher Avrami constant values (n) in the PpR-nucleated composite PCL films (n similar to 3), indicating 3-dimensional crystal growth. In the case of neat PCL films, however, lower n values indicated crystal growth in 1-dimensions or 2-dimensions. Moreover, atomic force microscopic analyses showed large crests and pits in PpR-nucleated PCL composites, with irregular morphologies leading to higher surface roughness. To the contrary, the crests and pits were much smaller in the neat PCL films, resulting in lower surface roughness values. Finally, mechanical testing revealed higher tensile strength for PpR-nucleated PCL composites films, demonstrating larger load bearing capabilities. (c) 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018, 56, 1529-1537College of Textiles, North Carolina State University; Department of Science and Technology (DST), IndiaDepartment of Science & Technology (India); State of North Carolina; National Science FoundationNational Science Foundation (NSF) [ECCS-1542015]The authors acknowledge the financial support provided by the College of Textiles, North Carolina State University. I. Matai is thankful to the Department of Science and Technology (DST), India for providing the financial support. This work was performed in part at the Analytical Instrumentation Facility (AIF) at North Carolina State University, which is supported by the State of North Carolina and the National Science Foundation (Award No. ECCS-1542015). The AIF is a member of the North Carolina Research Triangle Nanotechnology Network (RTNN), a site in the National Nanotechnology Coordinated Infrastructure (NNCI)

Fabrication and Characterization of Poly(ε-caprolactone)/α-Cyclodextrin Pseudorotaxane Nanofibers

Multifunctional scaffolds comprising neat poly­(ε-caprolactone) (PCL) and α-cyclodextrin pseudorotaxanated in α-cyclodextrin form have been fabricated using a conventional electrospinning process. Thorough in-depth characterizations were performed on the pseudorotaxane nanofibers prepared from chloroform (CFM) and CFM/dimethylformamide (DMF) utilizing scanning electron microscopy (SEM), transmission electron microscopy (TEM), rheology, differential scanning calorimetry (DSC), thermogravimetric analyses (TGA), wide-angle X-ray diffraction (WAXD), and Instron tensile testing. The results indicate the nanofibers obtained from chloroform retain the rotaxanated structure; while those obtained from CFM/DMF had significantly dethreaded during electrospinning. As a consequence, the nanowebs obtained from CFM showed higher moduli and lower elongations at break compared to neat PCL nanowebs and PCL/α-CD nanowebs electrospun from CFM/DMF