Higher Elongation Ratio Research Articles

Physicochemical Properties and Tissue Structure of High Kernel Elongation Rice (Oryza sativa L.) Varieties as Affected by Heat Treatment.

Heat treatment could affect the structure and properties of rice varieties. The present study was conducted in order to determine the effects of heat treatment on the physicochemical properties and tissue structure of Mahsuri Mutan, Basmati 370 and MR219 rice varieties. The three rice varieties were subjected to heat treatment (ageing) at 90 °C, using an oven, for 3 h. After the heat treatment, the samples were cooled at room temperature (25 °C) for 1 h. Physicochemical properties, such as alkali digestion value, water uptake ratio, solids in cooking water, high kernel elongation ratio and amylose contents, were determined. The procedure used in determining both apparent and absolute amylose involved measuring the iodine affinity of defatted whole starch. Ahigh-performance anion-exchange chromatograph was used to analyse branch chain length distribution of amylopectin quantitatively. The starch structure of the rice samples was observed under a scanning electron microscope. Data collected on physicochemical traits, heat treatment and control (ageing and non-ageing) were subjected to an analysis of variance using SAS software version 9.4. In this study, Mahsuri Mutan and Basmati 370 showed superior high kernel elongation as compared to their respective rice progenies. This study also found that heat treatment directly affected the increasingly high kernel elongation for both populations. The phenotypic correlation co-efficient indicated that there was a high positive correlation between high kernel elongation and water uptake ratio, implying that selection for water uptake ratio would increase the high kernel elongation characteristic. The heat treatment showed significant difference in all the physicochemical traits of the varieties studied. Heat treatment also affected the very long branch chains of starch, such as amylose. Observation under an electron microscope showed that the samples subjected to heat treatment had more cracks on the tissue structure compared to normal rice samples. The hexagon structure in Mahsuri Mutan produced a greater elongation effect on its kernel. The findings from this study could be useful to breeders in the selection and development of a new high kernel elongation rice variety.

Evaluation of physicochemical characteristics and genetic diversity of widely consumed rice varieties in Kyaukse area, Myanmar

Consumer preferences are greatly influenced by eating and cooking qualities of rice grains, along with the economic value of a specific rice variety. This study was to evaluate ten rice varieties including the check variety IR64 on their physicochemical, cooking and eating qualities as well as to identify their genetic diversity using SSR markers. Most rice varieties are medium-grain types based on length-breadth ratio, whereas the famous Myanmar rice variety, Paw San Bay Kyar, (PSBK) is bold. PSBK showed the best cooking and eating quality traits with intermediate amylose content (AC), intermediate gelatinization temperature (GT), soft gel consistency (GC), and the highest elongation ratio among the studied rice varieties. Seventeen SSR markers linked with cooking and eating traits were used to assess the extent of polymorphism and genetic variation among ten rice varieties. There were 49 alleles in total, with an average of 2.88 alleles per locus. RM592 had the maximum number of alleles. The average PIC value ranged from 0.22 (RM540) to 0.77 (RM592). Cluster analysis with UPGMA method based on Jaccard’s similarity coefficient divided ten rice varieties into two main groups and four sub-clusters. In multiple regression analysis, RM190 and Wx primers were discovered to be significantly associated with AC, GC and GT of cooking and eating quality traits. This study could contribute to the choice of rice varieties with superior cooking and eating qualities for rice breeding programs by implementing physicochemical characteristics and molecular analysis.

Morphometric Analysis of Baghlan Province for Amu River Basin in Afghanistan using Remote Sensing and GIS

Baghlan province is located in north of Kabul and surrounded by Bamyan, Kunduz,Parwan, Takhar, and Samangan provinces. It lies on the core route to the north and North-eastern regions of Afghanistan, which in terms of geographical location (coordinates) 29 degrees and 31 minutes north latitude and 58 degrees and 48 minutes east longitude, it is located 230 km from Kabul along the Kabul-Mazar highway; In the past, this province had 12 districts, which has now been raised to 15 districts, but in our current study, it will discuss 12 districts, which are the same 15 districts; 15 districts were canceled because there were no changes in the calculations of morphometric analysis. The different morphometric analysis explains the physical appearance of the watershed, which are suitable for the areas of land development, soil protection, topography rise, and soil erosion (Horton, 1945). This study discloses that DEM and GIS method in calculating morphometric drainage parameters and their effect on hydrological features at the watershed level is suitable than the conservative methods. The complete basin means bifurcation ratio (Rb) is 2.43, which shows that the drainage pattern is partial by geographical structure. Doshi and Khinjan districts have a high elongation ratio (Re), Ruggedness number (Rn), basin relief (Bh). It shows that peak discharges and erosion are high in these basins. This study is very beneficial for applying rainfall aggregation and watershed management.

Laser-irradiation-induced dynamically recrystallized microstructure and properties of supersonic-particle-deposited Ni-Fe-Cr-Nb-Ti-Al high-entropy alloy coating

A recrystallization-refined Ni-Fe-Cr-Nb-Ti-Al high-entropy alloy coating was prepared by supersonic particle deposition followed by laser irradiation. The surface-interface morphology, microstructure, grain orientation, and phase were examined by scanning electron microscopy, energy-dispersive spectrometry, electron backscatter diffraction, and X-ray diffraction analyses, respectively. The inverse pole figure of the coating showed that a large number of ultrafine grains and even nanograins filled the entire microscopic image. In addition, the refined grains did not show obvious preferred orientations and indicated isotropic features. Further, the fatigue limit of the recrystallized coating was 252 MPa, and the ability to realize uniform plastic deformation and stable deformation was enhanced owing to the high tensile strength and elongation ratio, which were 3000 MPa and 14%, respectively. The coating had a friction coefficient of 0.189, residual stress of −14.3 ± 6 MPa, and microhardness of 720 kgf/mm 2 . The capacitance radius of the Nyquist plot indicated that passivation formation improved the shielding performance of the coating. • A recrystallization refining coating was prepared by LR on Al-alloy after SPD. • The UFGs and NGs showed diversified preferred orientation and isotropic feature. • The ability of uniform plastic deformation and stable deformation were enhanced. • The Nyquist showed the passivation improved coating shielding performance. • The friction coefficient was negatively correlated with the hardness.

A comparative study on the physicochemical, cooking and textural properties of fortified rice kernels prepared from raw and parboiled rice

SummaryFortified rice kernels (FRK) are extruded rice‐shaped kernels manufactured by blending broken rice flour and vitamin–mineral premix. In this study, four parboiled and three raw rice with intermediate amylose content (20–24%) were processed to manufacture FRK. The system parameters (torque and die pressure), physicochemical properties (length, lightness, water absorption index and water solubility index), cooking properties (cooking time, solid loss, elongation) and textural properties of FRK were analysed and correlated using the Pearson correlation coefficient. The torque and die pressure were 16.76–22.76 Nm and 92.56–136.41 bar, respectively. Compared to raw rice, the parboiled rice showed the highest torque, die pressure and axial expansion in uncooked FRK while longer cooking times, higher elongation ratio and hardness; lesser water absorption ratio and solid loss in cooked FRK. The raw rice FRK showed higher lightness. There was a significant difference between all FRK for water absorption index (1.74–2.52) and water solubility index (2.06–3.53%).

Inheritance of kernel elongation in F2 rice populations crossed between Indian rice basmati 370 and selected Malaysian rice varieties

The speciality rice variety such as Basmati and Jasmine maybe not be very suitable to plant under the Malaysian climate because the growth may be influenced by the changes in the environmental conditions causing the changes of its physical and chemical characters and results in low yield. Thus, an attempt was made through a hybridisation program among selected Malaysian rice varieties consist of MRQ50, MRQ74, MRQ76, MR219, Mahsuri Mutant, and Mahsuri Mutant 98 with Indian traditional rice, Basmati 370 with the main objectives, to compare the kernel elongation ratio of each cross and to determine the potential and suitable combination among crosses rice for further evaluation program. The results of the study indicated that among parental lines, Basmati 370 posed the highest elongation ratio 2.00 which revealed its speciality elongation trait of cooked rice. A comparison between crosses, rice cross between Basmati 370 and Mahsuri Mutant 98 showed the highest elongation ratio with the value 2.12 and the lowest elongation ratio of about 1.96 was found in rice cross between Basmati 370 and MR219. However, all hybridised rice poses a value of elongation ratio more than 1.6 which is considered good kernel elongation. The segregation pattern of all crosses also posed a ratio 3:1 whereas three is low elongation and one is high elongation which demonstrated the Mendelian inheritance of monogenic cross. The results obtained from this study could contribute to the existing literature on speciality rice production in Malaysia and beneficial for future rice quality improvement program.

A zwitterionic terpolymer based coating potentially for antibacterial and antifouling applications

Antifouling materials are highly demanded in global marine market due to increasingly aggravated marine biofouling problem and unbalanced marine ecology. Herein, poly (vinyl imidazole-co-hydroxypropyl methacrylate-co-butyl acrylate) (P(VIm-co-HPMA-co-BA)) was prepared via free radical polymerization of commercially available monomers of vinyl imidazole (VIm), hydroxypropyl methacrylate (HPMA) and butyl acrylate (BA). Then the zwitterionic terpolymer (P(VPS-co-HPMA-co-BA)) was obtained by ionicalization of P(VIm-co-HPMA-co-BA) with 1, 3-propionate lactone (1, 3-PS) in EtOH solutions. Furthermore, the membrane samples, P(VIm-co-HPMA-co-BA) and P(VPS-co-HPMA-co-BA) were prepared by tape casting method with DI water bath. Significantly, P(VPS-co-HPMA-co-BA) membranes have shown better bactericidal activity against Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) with a mean area size of 3.5 cm2. Meanwhile, the bacterial adhesion assay showed that P(VPS-co-HPMA-co-BA) membranes were found the absence of adherent bacteria, and exhibited excellent anti-adhesion property with the increase of molar ratios of PVPS by the observation of bacteria population density. The mechanical testing results indicated that the molar ratios of 65/10/25 in P(VIm-co-HPMA-co-BA) membranes and P(VPS-co-HPMA-co-BA) membranes had high breaking elongation ratio and great tensile strength. Specifically, the maximum tensile strength of P(VPS-co-HPMA-co-BA) membrane could reach up to 10.9 MPa. The results showed that the novel P(VPS-co-HPMA-co-BA) membrane exhibited both anti-bacterial, anti-adhesion property and mechanical performance, manifesting its prospectively potential applications in new highly efficient and eco-friendly marine antifouling coatings.

Evaluation of Physicochemical and Cooking Characteristics of Rice (Oryza sativa L.) Landraces of Lamjung and Tanahun Districts, Nepal.

After the Green Revolution, the increase in the choice of modern varieties at the expense of landraces has become a major cause of varietal loss. The preference, choice, and the economy of rice (Oryza sativa L.) largely depend on its physicochemical and cooking properties, which are found to be superior for landraces than modern varieties. In this study, we assessed and evaluated milled rice of 30 rice landraces on their physicochemical and cooking characteristics which aim to promote the revival of old landraces. Six parameters of physical properties, four parameters of chemical properties, and five parameters of cooking properties were evaluated based on the standard protocols. Significant variations (p < 0.05) were found in all the properties that were evaluated. The result showed that the highest milling recovery was found in Indrabeli (75.55%) whereas the lowest was found in Kalo Masino (66.98%) and bulk density ranged from 0.81 g/cm3 to 0.88 g/cm3 showing not much variability. Although most of them were of medium grain type, their 1000 kernel weight varied between 12.62 g and 25.65 g. From the observed chemical properties, Pahelo Anadi (9.73 ± 0.55 mm) showed the highest gel consistency and lowest apparent amylose content (7.23 ± 0.36%). Also, 13% of landraces possessed strong aroma while noble cooking properties were showed by Thakali Lahare Marsi with the highest elongation ratio (2.41 ± 0.05) and by Chiniya with the lowest gruel solid loss (0.033 ± 0.03%) and minimum optimum cooking time (23.45 ± 0.03 min). In the principal component analysis, the first four principal components retained 73.8% of the variance. The first and second principal components were mostly related with the physical and chemical characteristics while the third and fourth principal components were concerned with cooking characters. Superior characters possessed by rice landraces can be further assessed for the breeding programs so that the cultivation of these cherished rice landraces can be enhanced.

A Multi Criteria Approach for Morpho-tectonic Evaluation of Sai River Basin in Uttar Pradesh

Abstract The study integrates the morphometric analysis, lineament evaluation and fluvial geomorphology to investigate the morphotectonic setup of Sai basin. The Sai river basin forms an integral part of the central Ganga plain where the gentle slope is significantly controlled by intra-basinal tectonic activity. The fluvial setup of the Sai basin which comprises of vast old flood plains now is displayed as an entrenched river with straight channel symmetry with multiple sinuous bends. The structural control and geomorphic asymmetry can be well established by using multi criteria approach of morphometric parameters and lineament analysis. The morphometric analysis of the basin shows that the Sai river comprises of 5th order stream basin with high elongation ratio and high bifurcation ratio suggesting structural and tectonic controls. The form factor, drainage density, and length of overland flow shows low permeability with low infiltration rate indicating sheet erosion as a major denudational process. The lineament analysis from the stream pattern analysis indicates structural control for drainages while geomorphology corresponds to the landscape of the basin. The lineaments analysis shows a major NW-SE trend in concordance to present foreland basin. Thus, the study confirms that the Sai basin has conclusive evidences of morpho-tectonic control in the central Ganga plain indicating the role of the tectonics in basin evoluation.

A Comparison between the Grain Quality Parameters of Rice Grown under Organic and Inorganic Production System

India contributes about one-third of the world acreage under rice. Rice is available in over 5000 varieties, of which Basmati rice occupies a prime position on account of its extra long superfine slender grains, pleasant, exquisite aroma, fine cooking quality, sweet taste, soft texture, length-wise elongation with least breadth-wise swelling on cooking and tenderness of cooked rice. The present work was undertaken to compare the effect of an organic and inorganic method of cultivation on the quality of rice. The results revealed higher hardness, true density and percent porosity in inorganic grains of rice. Inorganic rice had better milling quality but cooking quality was found better of organic rice as evident from higher elongation ratio and swelling rate. Organically grown foods were found to be tastier in comparison to inorganic foods as organic samples scored higher for all the parameters of sensory. Moisture content was found higher in inorganic rice. The quantity of protein was less, but the quality was better in organic crops as measured by in-vitro protein digestibility. No definite trend was seen for effect of inorganic and organic mode of cultivation on total ash, crude fiber and carbohydrate content on rice crops. Iron was found to be significantly higher in organic rice (1.32 mg/100 g); phosphorus was significantly higher in inorganic rice (112.80 mg/100 g). No significant difference was observed in manganese, cobalt, zink and copper content of the produced from an organic and inorganic mode of cultivation.

Development of a flexible 3D printed scaffold with a cell-adhesive surface for artificial trachea

Trachea stents are widely used to treat stenosis arising from various trachea injuries. However, they are associated with inflammation, re-stenosis, and tracheal obstruction. Seeking to overcome these problems, the development of an artificial trachea using tissue engineering has been explored. However, the artificial trachea did not mimic the natural rigidity and flexibility of the trachea and provide the micro-environment necessary for re-epithelialization. In this study, we developed a thermoplastic polyurethane (TPU) trachea scaffold that possesses a restoration characteristic, using flexible 3D printed patterns, and an improved cell attachment performance, utilizing electrospun fibers. With the aim of enhancing flexibility, we compared two geometric tubes, one with a straight pattern (SP) and the other with a wave pattern (WP). Simulation results showed that the WP scaffold was more flexible than the SP scaffold. A tensile expansion and torsion experiment demonstrated lower tensile strength and elastic modulus, and higher elongation ratio and rotation angle of the WP scaffold. Addition of the electrospun layers increased the tensile strength and elastic modulus and decreased the elongation ratio and rotation angle of both the SP and WP scaffolds. The same trend was observed regardless of electrospinning. However, polycaprolactone (PCL)-based scaffolds displayed lower elongation ratio and rotation angle in simulations and experiments. Although the cell attachment capacity of TPU-based electrospun WP scaffolds was less than 10% that of PCL-based scaffolds, the former showed good initial cell attachment performance and their cell numbers increased by more than three times within a week. The improved biomechanical performance and cell affinity of the TPU trachea scaffold could be exploited in patient-customized grafts for trachea reconstruction.

CO 52 (IET 25487): A highly remunerative medium duration fine grain rice variety

In Department of Rice, Tamil Nadu Agricultural University, Coimbatore, a medium duration fine grain rice variety CO52 was released for cultivation in transplanted situation for late samba / thaladi season . CO52 rice variety recorded a mean grain yield of 6191 kg/ha and possessess quality grain traits comparable to the predominantly cultivated fine grain types. It is a derivative of the cross between BPT 5204 and CO(R) 50 which matures in 130-135 days. The variety was tested in the station trial for three (2009-2011)years, Multi Location Trial for two (2011-12 and 2012-13) years, Adaptive Research Trial for two (2013-14 and 2014-15) years, OFT for three (2013-14, 2014-15 and 2015-16) years and in AICRIP trial for two (2011 and 2015) years. CO52 variety is moderately resistant to insect pests viz., plant hoppers and leaf hoppers and diseases viz., blast, sheath rot, brown spot and sheath blight. It produces medium slender white rice with high milling percentage, high head rice recovery, high linear elongation ratio, intermediate amylose content, soft gel consistency and moderate gelatinization temperature indicating its suitability for cooking with a remunerative market price and consumer preference similar to Improved White Ponni and BPT 5204.

Development and Introduction of Technology and Equipment for Multiple Drawing of Copper Alloy Thin-Walled Tube on a Long Movable Mandrel Without Intermediate Heat Treatment

Thin-walled and extremely thin-walled tubes made of copper alloys, i.e., brass grades L96, L68, L63, LANKMts, and the bronze grades BrOF6.5-0.15, BrOF4-0.25, are in great demand in the aircraft, shipbuilding, automotive, defense, diesel-locomotive building, and instrument-making industries. A promising manufacturing method is multiple drawing on a long movable mandrel without intermediate heat treatment due to such advantages as high total elongation ratios (λ = 3.0–6.0), simplicity of the equipment of the flow line, high productivity equal to 1200–1600 m/h, as well as good pipe surface quality and size precision. These advantages of the new method of manufacturing cold-deformed pipes make it possible to reduce the cyclic nature of manufacturing and processing costs. The work provides a methodological basis of theoretical analysis and design of rational routes for manufacturing colddeformed pipes by multiple deformation without intermediate heat treatment. As an example, the results are presented for calculation of three-fold drawing of thin-walled pipes made of brass grades L96, L68 and L63. Research results are used in the development of innovative technology for pipe manufacture from copper alloys at the PAO Revda Non-Ferrous Metal Processing Plant using a highly efficient three-fold drawing line on a long movable mandrel. One of the versions for line equipment layout is provided.

Crystal engineering of lactose using electrospray technology: carrier for pulmonary drug delivery

Context: Dry powder inhalers (DPIs) consisting of a powder mixture containing coarse carrier particles (generally lactose) and micronized drug particles are used for lung drug delivery. The effective drug delivery to the lungs depends on size and shape of carrier particles. Thus, various methods have been proposed for engineering lactose particles to enhance drug delivery to lungs.Objective: The objective of current work was to assess suitability of electrospray technology toward crystal engineering of lactose. Further, utility of the prepared lactose particles as a carrier in DPI was evaluated.Materials and methods: Saturated lactose solutions were electrosprayed to obtain electrosprayed lactose (EL) particles. The polymorphic form of EL was determined using Fourier transform infrared spectroscopy, powder X-ray diffractometry, and differential scanning calorimetry. In addition, morphological, surface textural, and flow properties of EL were determined using scanning electron microscopy and Carr’s index, respectively. The aerosolization properties of EL were determined using twin-stage impinger and compared with commercial lactose particles [Respitose® (SV003, Goch, Germany)] used in DPI formulations.Results and discussion: EL was found to contain both isomers (α and β) of lactose having flow properties comparable to Respitose® (SV003). In addition, the aerosolization properties of EL were found to be significantly improved when compared to Respitose® (SV003) which could be attributed to morphological (high elongation ratio) and surface characteristic (smooth surface) alterations induced by electrospray technology.Conclusion: Electrospray technology can serve as an alternative technique for continuous manufacturing of engineered lactose particles which can be used as a carrier in DPI formulations.

Effects of mechanical stretching on space charge behaviors of PP/POE blend for HVDC cables

Polypropylene (PP) blended with polyolefin elastomer (POE) has been considered as a potential choice to replace XLPE as HVDC cable insulating material, which shows excellent performance in electrical, mechanical and thermal properties. The space charge accumulation, formed under dc stress in PP/POE blend, would distort the local electric field, and furtherly lead to partial discharge or premature breakdown. During the processes of fabrication, installation and operation, the cable insulating material may be exposed to mechanical stress. In order to study the influence of mechanical stretching on space charge behaviors, PP/POE blends were prepared and stretched to different ratios of 1, 1.1, 1.2, 1.3 and 1.4, and the space charge behaviors in polarization and depolarization processes were measured and analyzed. The results indicate that a larger number of space charges accumulate in stretched specimens after polarization for the same time, and they decay faster than those in original specimens during depolarization process. Besides, the trap depth decreases with the increasing elongation ratio and then increases at a higher elongation ratio. The microstructure changes of PP/POE blend after mechanical stretching is considered to be responsible for the observed phenomena.

Glacial geomorphology of the northwestern Weddell Sea, eastern Antarctic Peninsula continental shelf: Shifting ice flow patterns during deglaciation

During the Last Glacial Maximum, grounded ice from the expanded Antarctic Peninsula Ice Sheet extended across the continental shelf. Grounded and flowing ice created a distinctive array of glacial geomorphic features on the sea floor, which were then exposed as the ice sheet retreated. The recent disintegration of the northern parts of the Larsen Ice Shelf (Larsen A and B) have permitted acquisition of marine geophysical data in previously inaccessible and unmapped areas. We present a reconstruction of the evolving ice-flow path and ice sheet geometry of the eastern Antarctic Peninsula, with particular focus paid to newly surveyed areas that shed light on the dynamics of a marine-terminating glacial geomorphic environment, where ice shelves play a major role in grounding line stability. Shifting flow directions were mapped in several areas, including across the Seal Nunataks, which divide Larsen A and B, and offshore of Larsen C, indicating flow reorientation that reflects the changing ice sheet geometry as retreat neared the modern coastline. The measured flow indicators in this area reveal comparatively high elongation ratios (>20), indicating rapid ice flow. Evidence of possible previous ice-shelf collapses are noted near the shelf break, further illustrating the critical, protective effect that ice shelves impart to marine-terminating glacial environments. Modern ice retreat is governed in part by reorganization of flow patterns accompanying grounding line movement; such reorganizations happened in the past and can aid understanding of modern processes.

Experimental study on uniaxial tensile and welding performance of a new coated fabric for airship envelopes

This paper investigated the mechanical properties of GQ-6 subjected to a tremendous amount of uniaxial tests. Such material is a new kind of ultra high molecular weight polyethylene fiber and aimed to be adopted in stratospheric airship. To begin with, mono-uniaxial tensile tests were conducted. The cycling-uniaxial tensile experiments were then carried out on the basis of the mono-uniaxial tensile tests data. Finally, performances of welding seams were thoroughly investigated with forty welding specimens. Results of mono-uniaxial tensile tests revealed that such woven fabric possesses high tensile strength and low elongation ratio at break. Meanwhile, the stress–strain behaviors were fitted by the Ogden model and a good agreement between such model and experimental data was obtained. Influences of the uniaxial loading cycle on such woven stiffness were discussed and the elastic moduli were defined with a standard hysteresis loop. For the welding tests, four types of overlapping welding failures were discovered. Compared with intact specimens, an appropriate welding width of 60 mm and an approximate 15% discount of the ultimate tensile stress on the intact textile were obtained.

Distribution of Fatty Acids and Their Ratios in Indian Rapeseed-Mustard Germplasm

A germplasm collection of 49 entries comprising 44 germplasm of Brassica juncea (Indian mustard), 3 low erucic acid varieties of B. juncea and two double zero varieties of Brasssica napus (gobhi sarson) were analyzed for fatty acid composition of their seed oil. All the 44 germplasm of B. juncea showed high level of erucic acid content. The highest erucic acid content (46.82%) was observed in germplasm UP-II-127. The u-6/u-3 ratio varied from 0.83–2.84. Oleic to linoleic acid ratio (stability index) ranged from 0.58–2.90 in different genotypes. The genotypes with high elongation ratio accumulated high amount of erucic acid and high desaturation efficiency was observed in B. juncea varieties low in erucic acid content. Low erucic varieties of B. juncea showed increase in oleic and linoleic acid content while double zero varieties of B. napus showed proportional increase in oleic acid content with reduction of erucic acid content.

Self‐Healing Poly(acrylic acid) Hydrogels: Effect of Surfactant

SummaryPhysical poly(acrylic acid) gels were prepared by micellar copolymerization of hydrophilic monomer acrylic acid with large hydrophobic monomer stearyl methacrylate (C18) in solutions of worm‐like anionic surfactant (sodium dodecyl sulfate, SDS) and cationic surfactant (cetyltrimethyl ammonium bromide, CTAB) micelles. Hydrophobe content of the monomer mixtures was 2 mol.% and total monomer concentration in gels was 20 w/v%. Gelation reactions were monitored by rheometry using oscillatory deformation tests. Hydrogel samples were also subjected to uniaxial elongation and compression tests after preparation and swelling. The physical gels with SDS and CTAB showed similar properties as long as they are at the state of preparation, such as insoluble in water and exhibit time‐dependent dynamic moduli, high Young's modulus, high fracture stress, high elongation ratios at break. Also self‐healing was evidenced by mechanical measurements. Physical gels formed in SDS solution were stable, exhibited high equilibrium swelling ratios and SDS progressively extracted from the network in water. On the other hand, gels with CTAB formed a complex and resulted in shrinkage after gels were immersed in a large excess of water because both electrostatic interactions between the charged components and hydrophobic interactions between the polymer backbone and the alkyl chains of the surfactant are important in driving the self‐assembly of molecules to form ordered structures. These structures of the polyelectrolyte surfactant complexes have unusual mechanical properties. Also, the hydrogel samples with CTAB self‐healed via heating and surfactant treatment of the damaged areas withstand up to 1.05 MPa stresses and rupture at a stretch of 800%.

In vitro evaluation of random and aligned polycaprolactone/gelatin fibers via electrospinning for bone tissue engineering

Scaffold, as an essential element of tissue engineering, should provide proper chemical and structural cues to direct tissue regeneration. In this study, aligned and random polycaprolactone (PCL)/gelatin fibrous scaffolds with different mass ratio were electrospun. Chemical, structural, and mechanical properties of PCL/gelatin fibrous scaffolds were characterized by FTIR and tensile measurements. The average diameters of different groups were between 334.96 ± 41.43 nm and 363.78 ± 50.49 nm. Blending PCL with gelatin increased the mechanical properties of the scaffolds. The cell culture results demonstrated that the mass ratio of PCL and gelatin showed no obvious effects on cell behavior, whereas the cell growth behavior was affected by the fibers orientation. Higher elongation ratio, enhanced cell proliferation and elevated alkaline phosphatase activity were observed for cells cultured on aligned fibers. The findings in our research provide insightful information for the design and fabrication of scaffolds for bone tissue engineering.