Edible Biopolymers-Based Materials for Food Applications—The Eco Alternative to Conventional Synthetic Packaging

The problem of waste generated by packaging obtained from conventional synthetic materials, often multilayer, has become more and more pressing with increasing consumption. In this context, nature and humanity have suffered the most. In order to address this phenomenon, global and European organizations have launched and promoted programs and strategies. Replacing petroleum-based packaging with biopolymer packaging has proven to be a real alternative. Thus, the substitution of plastics with biodegradable, non-toxic, edible materials, which can be obtained from marine or agro-industrial waste, is of interest. In the present study, we aimed to develop natural edible materials, obtained entirely from biopolymers such as agar and sodium alginate and plasticized with glycerol and water. Designed to be used for food and food supplements packaging, they can be completely solubilized before consumption. The films were developed through a casting method and were tested in order to identify the physical, optical, and solubility properties. According to the results, the most suitable composition for use as a hydrosoluble packaging material contains agar:alginate:glycerol in a 2:1:1 ratio. The microstructure indicates a homogeneous film, with low roughness values (Rz = 12.65 ± 1.12 µm), high luminosity (92.63), above-average transmittance (T = 51.70%), and low opacity (6.30 A* mm−1). The obtained results are of interest and highlight the possibility of substituting intensely polluting materials with those based on biopolymers.

Tuning crumpled sheets for an enhanced flexoelectric response

Flexoelectricity is a universal phenomenon present in all dielectrics that couples electrical polarization to strain gradients and vice-versa. Thus, structures and configurations that permit large strain gradients facilitate the design of an enhanced electromechanical coupling. In a recent work, we demonstrated the prospects for using crumpling of essentially arbitrary thin sheets for energy harvesting. Crumples, with their defect-like nature, admit singular and rapidly varying deformation fields and are thus ideal for engineering sharp non-uniformities in the strain field. In this work, we consider how to tune the design of crumpled sheets for a significant flexoelectric response. Specifically, we analytically derive the electromechanical coupling for a thin crumpled sheet with varying thickness and graded Young’s modulus as key design variables. We show that, the electromechanical coupling of such crumpled sheets can be tuned to be nearly five times those of the homogeneous film.

A Swelling Study in Different PH and Mechanical Properties of Biodegradable Films Based on Pluronic F-127/ Poly-Vinyl Alcohol

PluronicF-127/PVA polymeric biomaterials blend films plasticized with glycerin were prepared by solvent molding method. The polymer blend films were characterized using Fourier transform infrared (FTIR) spectroscopy, Field Emission Scanning Electron Microscopy and mechanical measurements. The FTIR spectra of the two polymers and their blends show that there is no chemical interaction between the PVA and the PluronicF-127. FESEM images indicate that blend homogeneous film can easily be prepared. Mechanical and swelling properties of the studied blends indicate that these can be used for medical application such as biodegradable materials and biodegradable drugs carriers and as food packaging materials.

Synthesis and photocatalytic degradation ability evaluation for rhodamine B of ZnO@SiO2 composite with flower-like structure

ZnO@SiO2 composite with flower-like structure was successfully prepared with molar ratio of ZnO/SiO2 = 1:1 based on the optimized synthesizing parameters of spherical SiO2 and flower-like ZnO. SiO2 particles were coated on the flower-like ZnO to form a homogeneous film through the multidimensional polycondensation of Si(OH)4. The photocatalytic degradation ability of ZnO@SiO2 composite for rhodamine B (RhB) obtained at different ZnO/SiO2 molar ratio and the comparison to that of flower-like ZnO showed that ZnO@SiO2 composite with ZnO/SiO2 molar ratio of 1:1 displayed a relatively good photocatalytic degradation ability to degrade RhB, but it was weaker than that of flower-like ZnO. Twenty millilitres of RhB solution at a concentration of 15 mg·L−1 could be completely degraded by 300 mg flower-like ZnO powder within 3 h, while the degrading efficiency was only 82.5% by 300 mg ZnO@SiO2 composite. But ZnO@SiO2 composite showed a better photocatalytic activity than flower-like ZnO at a lower pH value of 4.5.

Benefits of the Hydrophobic Surface for CH3NH3PbI3 Crystalline Growth towards Highly Efficient Inverted Perovskite Solar Cells

In inverted perovskite solar cells (PSCs), high-quality perovskite film grown on hole-transporting material (HTM) with pinhole-free coverage and a large grain size is crucial for high efficiency. Here, we report on the growth of pinhole-free and large grain CH3NH3PbI3 crystals favored by a hydrophobic small molecular HTM, namely, 4,4′-Bis(4-(di-p-toyl)aminostyryl)biphenyl (TPASBP). The hydrophobic surface induced by TPASBP suppressed the density of the perovskite nuclei and heterogeneous nucleation, thus promoting the perovskite to grow into a dense and homogeneous film with a large grain size. The CH3NH3PbI3 deposited on the TPASBP exhibited better crystallization and a lower trap density than that on the hydrophilic surface of indium tin oxide (ITO), resulting in a significant reduction in carrier recombination. Combined with the efficient hole extraction ability of TPASBP, a high efficiency of 18.72% in the inverted PSCs fabricated on TPASBP was achieved.

Кинетика фототока УФ-сенсора на основе нанонитей индий-цинк оксида

The paper presents an analysis of the experiments on current rise and fall kinetics under the influence of hard ultraviolet radiation on the indium-zinc oxide fibrous layer obtained by electrospinning. It is shown that the photocurrent increase rate can be varied by the radiation intensity, and its decrease – by the oxygen partial pressure on the nanofibers’ surface. The proposed UV sensor with a layer of nanoscale fibers possesses a higher response rate as compared to that of homogeneous film structures due to the significantly larger area of the active surface, where the centers of oxygen adsorption are concentrated.

EFFECTS OF VARIOUS TREATMENTS ON SILICONE RUBBER SURFACE

ABSTRACTHydroxy groups were generated on a poly(dimethylsiloxane) (PDMS) surface using different methods. Attempts were made to prepare a homogeneous film on the PDMS surface and eliminate microwrinkles from the surface. Because the hydroxylation process changes the chemical composition of the PDMS surface, resulting in a cracked surface, selecting the best method for surface treatment with minimized surface microwrinkles and cracks was attempted. The results obtained from scanning electron microscopy showed that using the pulsed ultraviolet-ozone (UVO) radiation method with a controlled duration time, ozone treatment, continuous UVO treatment using a glass filter, and water media in UVO treatment was more effective than other methods evaluated in this study to prevent microwrinkles. The results obtained from contact angle measurements and attenuated total reflectance Fourier transform infrared spectroscopy revealed that the UVO treatment in the presence of a water medium created more hydroxy groups compared with other methods.

Single-molecule magnet behavior in 2,2’-bipyrimidine-bridged dilanthanide complexes

A series of 2,2’-bipyrimidine-bridged dinuclear lanthanide complexes with the general formula [Ln(tmhd)3]2bpm (tmhd = 2,2,6,6-tetramethyl-3,5-heptanedionate, bpm = 2,2’-bipyrimidine, Ln = Gd(III), 1; Tb(III), 2; Dy(III), 3; Ho(III), 4 and Er(III), 5) has been synthesized and characterized. Sublimation of [Tb(tmhd)3]2bpm onto a Au(111) surface leads to the formation of a homogeneous film with hexagonal pattern, which was studied by scanning tunneling microscopy (STM). The bulk magnetic properties of all complexes have been studied comprehensively. The dynamic magnetic behavior of the Dy(III) and Er(III) compounds clearly exhibits single molecule magnet (SMM) characteristics with an energy barrier of 97 and 25 K, respectively. Moreover, micro-SQUID measurements on single crystals confirm their SMM behavior with the presence of hysteresis loops.