Functional Bi2O3/Gd2O3 Silica-Coated Structures for Improvement of Early Age and Radiation Shielding Performance of Cement Pastes.

This study presents a new approach towards the production of sol-gel silica-coated Bi2O3/Gd2O3 cement additives towards the improvement of early mechanical performance and radiation attenuation. Two types of silica coatings, which varied in synthesis method and morphology, were used to coat Bi2O3/Gd2O3 structures and evaluated as a cement filler in Portland cement pastes. Isothermal calorimetry studies and early strength evaluations confirmed that both proposed coating types can overcome retarded cement hydration process, attributed to Bi2O3 presence, resulting in improved one day compressive strength by 300% and 251% (depending on coating method) when compared to paste containing pristine Bi2O3 and Gd2O3 particles. Moreover, depending on the type of chosen coating type, various rheological performances of cement pastes can be achieved. Thanks to the proposed combination of materials, both gamma-rays and slow neutron attenuation in cement pastes can be simultaneously improved. The introduction of silica coating resulted in an increment of the gamma-ray and neutron shielding thanks to the increased probability of radiation interaction. Along with the positive early age effects of the synthesized structures, the 28 day mechanical performance of cement pastes was not suppressed, and was found to be comparable to that of the control specimen. As an outcome, silica-coated structures can be successfully used in radiation-shielding cement-based composites, e.g. with demanding early age performances.

Facile Strategy for Boosting of Inorganic Fillers Retention in Paper.

Achieving the desired properties of paper such as strength, durability, and printability remains challenging. Paper mills employ calcium carbonate (CaCO3) as a filler to boost paper's brightness, opacity, and printability. However, weak interaction between cellulose fibers and CaCO3 particles creates different issues in the papermaking industry. Therefore, this study explores the influence of various inorganic additives as crosslinkers such as mesoporous SiO2 nanospheres, TiO2 nanoparticles, h-BN nanoflakes, and hydroxylated h-BN nanoflakes (h-BN-OH) on inorganic fillers content in the paper. They were introduced to the paper pulp in the form of a polyethylene glycol (PEG) suspension to enable bonding between the inorganic particles and the paper pulp. Our findings have been revealed based on detailed microscopic and structural analyses, e.g., transmission and scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and N2 adsorption/desorption isotherms. Finally, the inorganic fillers (CaCO3 and respective inorganic additives) content was evaluated following ISO 1762:2001 guidelines. Conducted evaluations allowed us to identify the most efficient crosslinker (SiO2 nanoparticles) in terms of inorganic filler retention. Paper sheets modified with SiO2 enhance the retention of the fillers by ~12.1%. Therefore, we believe these findings offer valuable insights for enhancing the papermaking process toward boosting the quality of the resulting paper.

Sandwich-type architecture film based on WS2 and ultrafast self-expanded and reduced graphene oxide in a Li-ion battery.

Since its discovery, graphene has been widely considered a great material that has advanced the Li-ion battery field and allowed development in its performance. However, most current graphene-related research is focused on graphene-based composites as electrode materials, highlighting the role of graphene in composite materials. Herein, we focused on a three-dimensional composite film with unique sandwich-type architecture based on ultrafast self-expanded and reduced graphene oxide (userGO) and exfoliated WS2. This strategy allows non-active agents [e.g., carbon black and poly (vinylidene fluoride)] free electrodes in LIBs in the form of a film. The ultra-quick exothermal nature of the USER reaction allows the rapid release of internally generated gases to create highly porous channels inside the film. Hence, the improved Li-ion transport in the LIBs boosted the electrochemical performance of both film components (ex-WS2 and reduced graphene), resulting in a high specific capacity of 762 mAh/g at .05 A/g and high Coulombic efficiency (101%) after 1,000 cycles. Overall, userGO showed the highest capacity at a low current, and ex-WS2 provided a higher reversible capacity. These results showed that the expanded graphene layer is an excellent shield for ex-WS2 to protect against pulverization, promoting both stability and capacity.

Influence of Hydrogenation on Morphology, Chemical Structure and Photocatalytic Efficiency of Graphitic Carbon Nitride.

In this contribution, the effect of hydrogenation conditions atmosphere (temperature and time) on physicochemical properties and photocatalytic efficiency of graphitic carbon nitride (g-C3N4, gCN) was studied in great details. The changes in the morphology, chemical structure, optical and electrochemical properties were carefully investigated. Interestingly, the as-modified samples exhibited boosted photocatalytic degradation of Rhodamine B (RhB) with the assistance of visible light irradiation. Among modified gCN, the sample annealed at 500 °C for 4 h (500-4) in H2 atmosphere exhibited the highest photocatalytic activity-1.76 times higher compared to pristine gCN. Additionally, this sample presented high stability and durability after four cycles. It was noticed that treating gCN with hydrogen at elevated temperatures caused the creation of nitrogen vacancies on gCN surfaces acting as highly active sites enhancing the specific surface area and improving the mobility of photogenerated charge carriers leading to accelerating the photocatalytic activity. Therefore, it is believed that detailed optimization of thermal treatment in a hydrogen atmosphere is a facile approach to boost the photoactivity of gCN.

Poly(vinylidene fluoride) and Carbon Derivative Structures from Eco-Friendly MOF-5 for Supercapacitor Electrode Preparation with Improved Electrochemical Performance.

Electrodes from carbonized Zn4O(1,4-benzodicarboxylic acid) (MOF-5) structures were prepared successfully via evaporating the solvent with a poly(vinylidene fluoride) (PVDF) binder. The solvent used for a nanocomposite cast was easily removed. Such an elegant method for preparing electrodes provides a facile, cost-effective, and void/cracking-free nanocomposite distribution on the current collector. The highly porous nanoparticles containing pure carbon attach well to the PVDF membrane which results in an increased active surface area of the electrode to 847 m²/g. The electrochemical analysis shows that the best weight ratio of CMOF-5 to PVDF equals 85:15, 80:20, and 75:25, respectively. The specific capacitance of these samples is 218 F/g, 210 F/g, and 180 F/g, correspondingly. An additional advantage of the electrode prepared from the carbonized MOF-5 is the possibility to synthesis MOF structures from recovered substrates used in its synthesis (distilled N,N-Dimethylformamide DMF and terephthalic acid recovered from polyethylene terephthalate waste). We will demonstrate this in this contribution as well. Furthermore, the carbonized MOF-5 can be recovered from the spent electrode and reused again in the electrochemical device.

Comparative evaluation of the direct analgesic efficacy of selected physiotherapeutic methods in subjects with knee joint degenerative disease - preliminary report.

BACKGROUND: The goals of the study were to evaluate the efficacy of two physiotherapeutic procedures: low energy laser therapy and low frequency transcutaneous electric nerve stimulation (TENS) and to compare these modalities with regard to their therapeutic effects in patients with knee osteoarthritis. MATERIAL AND METHODS: Fifty (50) subjects were enrolled into the study and divided into two groups of 25 subjects. Group A received 10 MLS laser therapy sessions with a synchronised laser beam at doses of 12 J per treated site. Group B received ten sessions of low frequency TENS. The procedures were carried out every day for two weeks (5 times a week). All patients completed a personal data questionnaire and underwent an examination of knee joint motion range and circumference. Subjective pain intensity was assessed using the VAS pain scale and the modified Laitinen questionnaire. RESULTS: An analysis of the results of the treatment demonstrated statistically significant pain reduction in both groups. This improvement was significantly higher in the two-phase laser therapy group vs. the LF-TENS group. No statistically significant improvement was noted in either of the groups regarding the knee joint range of motion. CONCLUSIONS: 1. Synchronised laser beam (MLS) therapy and low-frequency TENS contribute to direct pain relief effects in subjects with knee osteoarthritis. 2. The study confirmed better analgesic effects of two-phase laser therapy vs. LF-TENS.