Cell-laden microengineered pullulan methacrylate hydrogels promote cell proliferation and 3D cluster formation

The ability to encapsulate cells in three-dimensional (3D) environments is potentially of benefit for tissue engineering and regenerative medicine. In this paper, we introduce pullulan methacrylate (PulMA) as a promising hydrogel platform for creating cell-laden microscale tissues. The hydration and mechanical properties of PulMA were demonstrated to be tunable through modulation of the degree of methacrylation and gel concentration. Cells encapsulated in PulMA exhibited excellent viability. Interestingly, while cells did not elongate in PulMA hydrogels, cells proliferated and organized into clusters, the size of which could be controlled by the hydrogel composition. By mixing with gelatin methacrylate (GelMA), the biological properties of PulMA could be enhanced as demonstrated by cells readily attaching to, proliferating, and elongating within the PulMA/GelMA composite hydrogels. These data suggest that PulMA hydrogels could be useful for creating complex, cell-responsive microtissues, especially for applications that require controlled cell clustering and proliferation.     

Synthesis and characterization of poly(p‐phenylene)‐graft‐poly(ε‐caprolactone) copolymers by combined ring‐opening polymerization and cross‐coupling processes

2,5‐Dibromo‐1,4‐(dihydroxymethyl)benzene was used as initiator in ring‐opening polymerization of ε‐caprolactone in the presence of stannous octoate (Sn(Oct)₂) catalyst. The resulting poly(ε‐caprolactone) (PCL) macromonomer, with a central 2,5‐dibromo‐1,4‐diphenylene group, was used in combination with 1,4‐dibromo‐2,5‐dimethylbenzene for a Suzuki coupling in the presence of Pd(PPh₃)₄ as catalyst or using the system NiCl₂/bpy/PPh₃/Zn for a Yamamoto‐type polymerization. The poly(p‐phenylenes) (PPP) obtained, with PCL side chains, have solubility properties similar to those of the starting macromonomer, ie soluble in common organic solvents at room temperature. The new polymers were characterized by ¹H and ¹³C NMR and UV spectroscopy and also by GPC measurements. The thermal behaviour of the precursor PCL macromonomer and the final poly(p‐phenylene)‐graft‐poly(ε‐caprolactone) copolymers were investigated by thermogravimetric analysis and differential scanning calorimetry analyses and compared. Copyright © 2004 Society of Chemical Industry     

Effect of fabrication parameters on the pore concentration of the aluminum metal foam, manufactured by powder metallurgy process

In this paper, the effect of fabrication parameters on the pore concentration of aluminum metal foam manufactured by powder metallurgy process is studied. Aluminum metal foam specimens were fabricated from the mixture of aluminum powders (mean particle size 60 μm) and NaCl at 10,20,30,40(wt) % content under 200, 250, 300, MPa Pressures. All specimens were then sintered at 630°C for 2.5 hours in an argon atmosphere. For pore formation (foaming), sintered specimens were immersed into 70°C hot running water. Finally the pore concentration of specimens was recorded to analyze the effect of fabrication parameters (namely NaCl ratio, NaCl particle size and compacting pressure) on the foaming behavior of compacted specimens. As a result of the study, it has been recorded that the above mentioned fabrication parameters are effective on pore concentration profile while pore diameters remained unchanged.     

Sulfated Hydrogel Matrices Direct Mitogenicity and Maintenance of Chondrocyte Phenotype through Activation of FGF Signaling

Deciphering the roles of chemical and physical features of the extracellular matrix (ECM) is vital for developing biomimetic materials with desired cellular responses in regenerative medicine. Here, it is demonstrated that sulfation of biopolymers, mimicking the proteoglycans in native tissues, induces mitogenicity, chondrogenic phenotype, and suppresses catabolic activity of chondrocytes, a cell type that resides in a highly sulfated tissue. Through tunable modification of alginate it is shown that increased sulfation of the microenvironment promotes fibroblast growth factor (FGF) signaling‐mediated proliferation of chondrocytes in a 3D matrix independent of stiffness, swelling, and porosity. Furthermore, for the first time it is shown that a biomimetic hydrogel acts as a 3D signaling matrix to mediate a heparan sulfate/heparin‐like interaction between FGF and its receptor leading to signaling cascades inducing cell proliferation, cartilage matrix production, and suppression of dedifferentiation markers. Collectively, this study reveals important insights on mimicking the ECM to guide self‐renewal of cells via manipulation of distinct signaling mechanisms.     

Comparison of multiple regression analysis using dummy variables and a NARX network model: an example of a heavy metal adsorption process

In the present study, the adsorption characteristics of coal fly ash obtained from the Kangal Power Plant, Turkey and activated fly ash in the planetary ball mill were investigated to remove the heavy metal ions from aqueous solutions. The adsorption capacity was compared for the first time using a multiple regression analysis with dummy variables and a non‐linear auto regressive exogenous (NARX) network model. An equation was obtained for all types of adsorbents or heavy metals using the regression of q_e on the dummy variables. The predictive ability of NARX was found to be better than that of multiple regression using dummy variables. These models can also be successfully implemented on the experimental data to evaluate the adsorption process. In addition, fly ash is a low cost alternative since it is a more economical and environmentally friendly adsorbent and it is abundant in both nature and from waste material from industry.     

Genetic algorithm with local search for the unrelated parallel machine scheduling problem with sequence-dependent set-up times

In this paper, a genetic algorithm (GA) with local search is proposed for the unrelated parallel machine scheduling problem with the objective of minimising the maximum completion time (makespan). We propose a simple chromosome structure consisting of random key numbers in a hybrid genetic-local search algorithm. Random key numbers are frequently used in GAs but create additional difficulties when hybrid factors are implemented in a local search. The best chromosome of each generation is improved using a local search during the algorithm, but the better job sequence (which might appear during the local search operation) must be adapted to the chromosome that will be used in each successive generation. Determining the genes (and the data in the genes) that would be exchanged is the challenge of using random numbers. We have developed an algorithm that satisfies the adaptation of local search results into the GAs with a minimum relocation operation of the genes’ random key numbers – this is the main contribution of the paper. A new hybrid approach is tested on a set of problems taken from the literature, and the computational results validate the effectiveness of the proposed algorithm.     

Shungite/poly(vinyl alcohol) hybrid hydrogels: An efficient adsorption material for rare earth metals in aqueous media

Rare earth elements play a pivotal role in modern technologies, thereby driving an escalating demand for their procurement. To effectively extract these elements from aqueous solutions, it is imperative to explore innovative sorbent materials. In this context, a hydrogel sorbent material was developed by employing poly(vinyl alcohol) (PVA) and shungite—an economical, naturally occurring, easily processable, and sustainable material. This was achieved through the freezing–thawing method, employing sodium borate as a crosslinking agent. The physicochemical characteristics of the hydrogels were determined through scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) analysis, Zetasizer analysis, and elemental analysis. The shungite-incorporated PVA hydrogels displayed notable characteristics, including a substantial swelling capacity of 61% and a specific surface area of 32.8 m²/g. Most significantly, these hydrogels exhibited a remarkable affinity for La³⁺ ions, with an uptake ratio of 134 mg/g. This was followed by Nd³⁺, Dy³⁺, and Er³⁺ ions, which displayed uptake ratios of 79, 74, and 73 mg/g, respectively.     

Synthesis and Characterization of Lipophilic Polymeric Adsorbent Resins for Recovery of Anthocyanins from Black Carrot

The aim of this study was to synthesize and characterize the various polymeric adsorbents which are used in the recovery of black carrot anthocyanins by the solid-phase extraction technique. In this context, acrylic and methacrylic monomers were polymerized with the free radical polymerization technique. In resin synthesis, four different crosslinker monomers, different monomer/crosslinker and monomer/diluent ratios were studied. The characterizations of the polymeric adsorbents were designed by size distribution, polymerization yield, scanning electron microscope images and swellability ratio in water and ethanol. In order to determine the best production conditions for polymer adsorbents, they were tested in a model batch system. The T-10-coded adsorbent demonstrated the best performance. The anthocyanins of the black carrot were recovered successfully from carrot juice by using the packed bed adsorption column system which is prepared with T-10. At the end of the study, 3.01 g color components were obtained from 1 L of black carrot juice.     

Production of SrCO3 and (NH4)2SO4 by the dry mechanochemical processing of celestite

A SrCO₃ formation starting from activated SrSO₄–(NH₄)₂CO₃ mixtures as a result of dry mechanochemical treatment for 180 min in a planetary ball mill of celestite together with (NH₄)₂CO₃ was studied. The phases that formed during milling were successfully characterized by X-ray diffraction measurement (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and chemical analysis. A novel hydrometallurgical process to convert both SrCO₃ (product) and (NH₄)₂SO₄ (by-product) from celestite via dry mechanochemical conversion with (NH₄)₂CO₃ was developed for the first time in this work. Under optimum conditions, the conversion of SrCO₃ was 98.1%. The (NH₄)₂SO₄ leach solution was crystallized.