Magnetically Guided Self‐Assembly and Coding of 3D Living Architectures

In nature, cells self‐assemble at the microscale into complex functional configurations. This mechanism is increasingly exploited to assemble biofidelic biological systems in vitro. However, precise coding of 3D multicellular living materials is challenging due to their architectural complexity and spatiotemporal heterogeneity. Therefore, there is an unmet need for an effective assembly method with deterministic control on the biomanufacturing of functional living systems, which can be used to model physiological and pathological behavior. Here, a universal system is presented for 3D assembly and coding of cells into complex living architectures. In this system, a gadolinium‐based nonionic paramagnetic agent is used in conjunction with magnetic fields to levitate and assemble cells. Thus, living materials are fabricated with controlled geometry and organization and imaged in situ in real time, preserving viability and functional properties. The developed method provides an innovative direction to monitor and guide the reconfigurability of living materials temporally and spatially in 3D, which can enable the study of transient biological mechanisms. This platform offers broad applications in numerous fields, such as 3D bioprinting and bottom‐up tissue engineering, as well as drug discovery, developmental biology, neuroscience, and cancer research.     

Effect of processing method on microstructure,electrical conductivity and electromagnetic wave interference (EMI) shielding performance of carbon nanofiber filled thermoplastic polyurethane composites

In this study, effect of processing method on microstructure formation and related electrical conductivity and electromagnetic interference shielding effectiveness of carbon nanofiber (CNF) filled thermoplastic polyurethane (TPU) composites, prepared via three different processing techniques; (i) melt compounding (MC) in a twin screw extruder, (ii) simple solution mixing (SM) on a magnetic stirrer, and (iii) solution mixing with sonication (SM-U) were investigated. It was found that the electrical conductivity values of samples decreased in the order of SM > SM-U > MC for a particular amount of CNF. The electromagnetic test results showed that the samples prepared with SM and SM-U methods yielded higher total shielding effectiveness (SE_T) values than those prepared with MC. SE_T values of samples including of 20 phr of CNF prepared with MC, SM-U and SM methods were varied in the range of 10–30 dB, 20–60 dB and 20–80 dB, respectively within a frequency range of 1–12 GHz.     

The impacts of water and ethanolic extracts of propolis on vacuum packaged sardine fillets inoculated with Morganella psychrotolerans during chilly storage

The impacts of water and ethanolic extracts of propolis at a dose of 0.4 or 0.8% on vacuum packaged sardine fillets inoculated with Morganella psychrotolerans DSM 17886 during storage at 3 ± 1°C for 15 days were investigated. All fish groups were inoculated with M. psychrotolerans (10⁸ cfu/ml) at a rate of 1%. Sensory, colorimetric, chemical analysis (total volatile basic nitrogen, thiobarbituric acid, peroxide values, and free fatty acids), pH value, and microbiological analysis (viable mesophilic and psychrophilic bacteria, coliform, and lactic acid bacteria count) were carried out. An enhance in L* values was found in the group treated with 0.8% ethanolic extracts of propolis on the seventh day of the storage. Application of propolis extract on fish fillets significantly inhibited bacterial growth during storage and extended shelf life of sardine for 4 and 6 days by the use of water extract and for 8 days by the use of ethanolic extract at doses of 0.4 and 0.8%, respectively. The result of the study revealed that application of propolis extracts, mainly ethanolic propolis extracts on sardine fillets resulted in lower lipid oxidation and bacterial growth, therefore, could be natural food additive for preservation of fish fillets.     

Isothermal crystallization kinetics of glass fiber and mineral-filled polyamide 6 composites

In this study, isothermal crystallization kinetics of polyamide 6 (PA6) composites reinforced with surface-treated glass fiber (GF) and natural, clay-type mineral (MN) were investigated by differential scanning calorimetry method in the presence and absence of a nucleating agent (NA). Microstructural features of the composites and interfacial interactions between filler and polyamide phases were also quantified by rheological measurements. The kinetic parameters for the isothermal melt-crystallization process of the samples were determined with the Avrami and Lauritzen–Hoffman models. The crystallization activation energies were determined by the Arrhenius method. It was found that the both fillers yielded a significant increase in the storage modulus of PA6. Kinetic calculations showed that the MN has a more pronounced acceleration effect on the crystallization rate of PA6 than the GF. Introduction of a small amount of NA significantly favored the isothermal crystallization rate of GF-reinforced PA6 but did not accelerate that of MN-reinforced one. Based on the results, it has been highlighted that PA6 composites reinforced with surface-treated GFs and including a small amount of clay-like mineral as a cheap and easy-accessible minor filler could yield the best performance for the injection-molded PA6 parts because the GF enhances the mechanical properties and the clay-like mineral accelerates the crystallization rate.     

Biogas production from municipal sewage sludge (MSS)

Biogas is produced by anaerobic (oxygen free) digestion of organic materials such as sewage sludge, animal waste, and municipal solid wastes (MSW). As sustainable clean energy carrier biogas is an important source of energy in heat and electricity generation, it is one of the most promising renewable energy sources in the world. Biogas is produced from the anaerobic digestion (AD) of organic matter, such as manure, MSW, sewage sludge, biodegradable wastes, and agricultural slurry, under anaerobic conditions with the help of microorganism. Biogas is composed of methane (55–75%), carbon dioxide (25–45%), nitrogen (0–5%), hydrogen (0–1%), hydrogen sulfide (0–1%), and oxygen (0–2%). The sewage sludge contains mainly proteins, sugars, detergents, phenols, and lipids. Sewage sludge also includes toxic and hazardous organic and inorganic pollutants sources. The digestion of municipal sewage sludge (MSS) occurs in three basic steps: acidogen, methanogens, and methanogens. During a 30-day digestion period, 80–85% of the biogas is produced in the first 15–18 days. Higher yields were observed within the temperature range of 30–60°C and pH range of 5.5–8.5. The MSS contains low nitrogen and has carbon-to-nitrogen (C/N) ratios of around 40–70. The optimal C/N ratio for the AD should be between 25 and 35. C/N ratio of sludge in small-scale sewage plants is often low, so nitrogen can be added in an inorganic form (ammonia or in organic form) such as livestock manure, urea, or food wastes. Potential production capacity of a biogas plant with a digestion chamber size of 500 m³ was estimated as 20–36 × 10³ Nm³ biogas production per year.     

Microleakage in class V cavities prepared using conventional method versus Er:YAG laser restored with glass ionomer cement or resin composite

This study evaluated the effect of tooth preparation method (diamond bur vs. Er:YAG laser) on the microleakage levels of glass ionomers and resin composite. Human permanent premolars (N = 80) were randomly divided into two groups (n = 40). Cavities on half of the teeth were prepared using diamond bur for enamel and carbide bur for dentin and the other half using Er:YAG laser. The teeth were randomly divided into four groups according to the restoration materials, namely (a) ChemFil Rock (CFR), (b) IonoluxAC (IAC), (c) EQUIA system (EQA) and one resin composite (d) AeliteLS (ALS) (n = 10 per group). Microleakage (μm) was assessed at the occlusal and gingival margins after dye penetration (0.5% basic fuchsine for 24 h). On the occlusal aspect, while the cavity preparation types significantly affected the microleakage for CFR (p = 0.015), IAC (p = 0.001) glass ionomer restorations, it did not show significant effect for glass ionomer EQA (p = 0.09) and resin composite ALS (p = 0.2). Er:YAG laser presented less microleakage compared to bur preparation in all groups except for EQA. On the gingival aspect, microleakage decreased significantly for CFR (p = 0.02), IAC (p = 0.001), except for EQA where significant increase was observed (p = 0.001) with the use of Er:YAG laser. Microleakage decrease was not significant at the gingival region between diamond bur and Er:YAG laser for ALS (p = 0.663). At the occlusal and gingival sites in all groups within each preparation method, microleakage level was not significant.     

The effect of using an exopolysaccharide‐producing culture on the physicochemical properties of low‐fat and reduced‐fat Kasar cheeses

A mixed starter culture containing exopolysaccharide (EPS)‐producing strains of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus was combined with Lactobacillus helveticus LH301 and used in the manufacture of low‐fat and reduced‐fat Kasar cheeses. For comparison, low‐fat (C10) and reduced‐fat (C20) cheeses were made using EPS‐producing (EPS⁺) starter strain and EPS‐non‐producing (EPS^?) starter strain. The physicochemical properties of the cheeses were assessed in terms of chemical composition, texture, microstructure and microbial content over 90 days. Cheeses made with EPS‐producing culture (EPS10 and EPS20) had lower protein contents than control cheeses with 10% and 20% fat in dry basis (C10 and C20). Scanning electron microscopy images showed that using EPS‐producing culture resulted in a less compact protein matrix and sponge‐like structure in the cheese samples. In general, cheeses made using EPS‐producing culture had lower total viable counts. This could be related to the reduced survivability of EPS‐producing cells in the cheese matrix during ripening due to autolysis ability.     

Rheological and Sensory Properties of Spray Dried Pekmez Mixtures with Wheat Starch-Gum

Pekmez, known also as grape molasses, was spray dried in the laboratory-type pilot drying unit to obtain pekmez powder. The flow characteristics of diluted pekmez powder (DPP), wheat starch (WS), and some hydrocolloids (locust bean gum, LBG; gum tragacanth, GT, and guar gum, GG) systems in double- or triple-mixed combinations were studied. The empirical power law model fitted the apparent viscosity-rotational speed data. DPP-gum and WS-gum mixed solutions exhibited a shear-thinning behaviour at 21°C with flow behaviour index (n) values of 0.88 ≤ n ≤ 0.94 and 0.17 ≤ n ≤ 0.32, respectively. WS-gum mixed solutions showed high shear-thinning behaviour with the highest consistency index (k = 49.93–214.24 Pa sⁿ). However, DPP-WS and DPP-WS-gum mixed solutions at the same temperature exhibited the shear-thickening behaviour with flow behaviour index (n) values of 1.02 ≤ n ≤ 1.07.     

Synthesis,conductivity and dielectric characterization of salicylic acid–Fe3O4 nanocomposite

We report on the synthesis of water dispersible salicylic acid –Fe₃O₄ nanocomposites via a co-precipitation route by using Fe(III) and Fe(II) chloride salts, and salicylic acid. Crystalline phase was identified as Fe₃O₄ and the crystallite size was obtained as 13 ± 6 nm from X-ray line profile fitting. As compared to the particle size of 20 nm obtained from TEM analysis these particles show polycrystalline nature. The capping of salicylic acid around Fe₃O₄ nanoparticles was confirmed by FTIR spectroscopy, the interaction being via bridging oxygens of the carboxylate and the nanoparticle surface. ac and dc conductivity measurements performed on the nanocomposite revealed semiconductor characteristics and varying trends with temperature due to reorganization of the nanocomposite. Permittivity measurements showed increasing dielectric constant with increasing temperature as expected from semiconductors. Analysis of electrical modulus and dielectric permittivity functions suggest that ionic and polymer segmental motions are strongly coupled in the nanocomposite.