RSC Advances

Joiner, Kevin L.; Tukeman, Gabriel L.; Obraztsova, Anna Y.; Arias-Thode, Yolanda Meriah

doi: 10.1039/d0ra03459bpmid: 35519731

The benthic microbial fuel cell (BMFC) is a promising technology for harvesting renewable energy from marine littoral environments. The scientific community has researched BMFC technology for well over a decade, but the in situ performance remains challenging. To address this challenge, BMFC power experiments were performed on sediment collected from San Diego Bay (CA, USA), La Spezia (Italy) and Honolulu (HI, USA) in the ever-changing littoral environment. Analysis of BMFC laboratory data found the power density varied substantially across 11 sites in San Diego Bay. In addition, data from experiments repeated at four locations in San Diego Bay showed significant differences between experiments performed in 2014, 2016 and 2019. Multivariable linear analysis showed BMFC 90 day cumulative power density was positively correlated with the total organic carbon (p < 0.05) and negatively correlated with the black carbon in the sediment (p < 0.05). Regression coefficients trained on the San Diego Bay data from 2014 facilitated accurate predictions of BMFC performance in 2016 and 2019. The modeling paradigm accurately explained variations in BMFC power performance in La Spezia and showed sediment parameters can impact BMFC performance differently across geographic regions. The results demonstrate a great potential to use sediment parameters and statistical modeling to predict BMFC power performance prior to deployment in oceanographic environments, thereby reducing cost, work force and resources.

Vogt, Linda I.; Cotelesage, Julien J. H.; Dolgova, Natalia V.; Titus, Charles J.; Sharifi, Samin; George, Simon J.; Pickering, Ingrid J.; George, Graham N.

doi: 10.1039/d0ra04653apmid: 35519739

Organic sulfoxides, a group of compounds containing the sulfinyl SO group, are widespread in nature, important in health and disease, and used in a variety of applications in the pharmaceutical industry. We have examined the sulfur K-edge X-ray absorption near-edge spectra of a range of different sulfoxides and find that their spectra are remarkably similar. Spectra show an intense absorption peak that is comprised of two transitions; a S 1s → (S–O)σ* and a S 1s → [(S–O)π* + (S–C)σ*] transition. In most cases these are sufficiently close in energy that they are not properly resolved; however for dimethylsulfoxide the separation between these transitions increases in aqueous solution due to hydrogen bonding to the sulfinyl oxygen. We also examined tetrahydrothiophene sulfoxide using both the sulfur and oxygen K-edge. This compound has a mild degree of ring strain at the sulfur atom, which changes the energies of the two transitions so that the S 1s → [(S–O)π* + (S–C)σ*] is below the S 1s → (S–O)σ*. A comparison of the oxygen K-edge X-ray absorption near-edge spectra of tetrahydrothiophene sulfoxide with that of an unhindered sulfoxide shows little change, indicating that the electronic environment of oxygen is very similar.

Li, Yubin; Xie, Ling; Yuan, Jiaming; Liu, Huazhong

doi: 10.1039/d0ra04202apmid: 35519757

In this work, an efficient and sensitive fluorometric sensor was developed to detect silver ions (Ag+). It is based on the cytosine–Ag+–cytosine (C–Ag+–C) structure via a dual-signal amplification strategy using glucose oxidase (GOx) and the hybridization chain reaction (HCR). A silver-coated glass slide (SCGS) acts as an ideal material for separation. Cytosine rich (C-rich) capture DNA (C-DNA) assembled themselves on the SCGS via Ag–S bonds and hybridized with signal DNA (S-DNA) to trigger the HCR. With specific base-pairing, the S-DNA and HCR products bind on the SCGS. Then, the GOx–biotin–streptavidin (SA) complexes bind to the HCR products through SA–biotin interactions. Owing to the formation of a particular C–Ag+–C structure between two neighboring C-rich C-DNA on the SCGS, the C-DNA/S-DNA/HP1-GOx/HP2-GOx complex gradually moved away from the SCGS as the concentration of Ag+ increased and the combined GOx fell into the buffer. H2O2 could be generated during the oxidation of glucose, catalyzed by GOx in the buffer. Afterward, H2O2 could oxidize the substrate (3-(p-hydroxyphenyl)-propanoic acid) when Horseradish peroxidase was present, giving rise to blue fluorescence. The proposed strategy reached a limit of detection (LOD) of 1.8 pmol L−1 with a linear detection range of 5 to 1000 pmol L−1 for Ag+. Moreover, this assay has been commendably used for the detection of Ag+ in actual samples with fairly good results.

Ding, Zhu; Wang, Shuo; Chang, Xue; Wang, Dan-Hong; Zhang, Tianhao

doi: 10.1039/d0ra03562apmid: 35519729

Photocatalytic nitrogen fixation has attracted extensive attention in recent years. Studies have shown that catalytic materials with O, N and other defects can effectively reduce the bond energy of NN triple bond when N2 is adsorbed on the defects. As an outstanding non-metallic catalyst, g-C3N4 has been widely studied in the field of photocatalytic catalysis, and the nitrogen-defected C3N4 shows promoted photocatalytic activity. Herein, nano-size MOF-74 particles (<20 nm) was dispersed on nitrogen-defected C3N4 thin film (∼4 nm) via a simple sol–gel method. The combination of Nano-MOF and defected film C3N4 could effectively improve the photocatalytic activity of nitrogen fixation through Z-scheme mechanism compared with pure defected film C3N4.

Lin, Jiaqi; Li, Yang; Liu, Xinmei; Li, Yuanshuo; Zheng, Weijie; Yang, Wenlong

doi: 10.1039/d0ra03859hpmid: 35519746

KTa1−xNbxO3 with different Ta/Nb ratios (x = 0.15, 0.25, 0.5, 0.75, 0.85) were engineered and prepared by a facile hydrothermal synthesis method to acquire KTN nanoparticles with varied polarity. To investigate the effect of KTN filler with varied polarity on the dielectric performance of polymer matrix composites, KTN/PVDF films were fabricated. The experiment demonstrated the polarity of KTN affected the dielectric performance of the composites. KTa0.5Nb0.5O3 possesses larger polarity with permittivity of 3780 at 1 kHz due to its Curie temperature is closer to room temperature, which contributes 30 wt% doped KTa0.5Nb0.5O3/PVDF composite achieving higher permittivity of 19.5 at 1 kHz than those of the others. Additionally, KTa0.75Nb0.25O3/PVDF composite presents higher breakdown strength than those of the others with an Eb value of 164 kV mm−1 when 20 wt% filler is doped. The significant improved dielectric performance by Ta/Nb ratio engineering has the potential of providing new insight on enhancing the energy storage in ceramic-polymer nanocomposites.

Kim, Dukeun; Lee, Taeheon; Kwon, Minho; Paik, Hyun-jong; Han, Jong Hun; Kang, Min; Choi, Jueun; Hong, Seungki; Kim, Yoong Ahm

doi: 10.1039/d0ra04061dpmid: 35519752

SWCNTs were individually dispersed in ethylne glycol (EG) via mild bath-type sonication using quaternized poly(furfuryl methacrylate)-co-(2-(dimethylamino)ethyl methacrylate) p(FMA-co-QDMAEMA) as a dispersing agent. QDMAEMA, which has alkyl groups, was more favorable to the dispersion ability of single walled carbon nanotubes (SWCNTs). The dispersion mechanism of SWCNTs in EG via helical wrapping of polymer chains along their sidewalls was suggested based on transmission electron microscopic observation.

Silva, Michael Jackson Ferreira da; Rodrigues, Alisson Mendes; Vieira, Italo Rennan Sousa; Neves, Gelmires de Araújo; Menezes, Romualdo Rodrigues; Gonçalves, Eloisa da Graça do Rosário; Pires, Maria Célia Costa

doi: 10.1039/d0ra00647epmid: 35519748

A stable moisturizing cosmetic emulsion was developed from babassu nut oil and high concentrations of sunscreens. Babassu nut oil was chosen because within the laboratory time-scale, this vegetable oil showed stable physicochemical properties (relative density, acidity index, and refracted index) and a good ratio between lauric and myristic fatty acids. The presence of these saturated fatty acids can confer specific activities to the cosmetic emulsion, such as antiviral, bactericidal, and anti-inflammatory activity. The prepared cosmetic emulsion, even after the centrifugation test (3000 rpm for 15 min), showed a creamy appearance with stable light-yellow coloration and the typical odor of babassu nut oil-based products. In the accelerated stability assays (pH, viscosity, and globule homogeneity), the cosmetic emulsion was kept at different temperatures (2.0 ± 0.2 °C (TG), 25 ± 2 °C (TA), and 40 ± 2 °C (TE)) and time durations (24 hours (t0), 7 days (t7), 15 days (t15), and 30 days (t30)). Finally, developed the cosmetic emulsion was investigated for occlusive properties and in vitro sun protection factor (SPF). Both were measured at room temperature and did not change significantly under the experimental conditions employed. The maximum experimental value measured in the in vitro occlusive test was equal to 34.2 ± 2.8, and the SPF was 39 ± 1.6 (t0) and 38 ± 2.9 (t30). In agreement with European and Brazilian legislations, the obtained babassu oil-based cosmetic emulsion is classified to have a high sun protection factor.

Mir, Shabir Ahmad; Gupta, Dinesh C.

doi: 10.1039/d0ra02817gpmid: 35519779

A cohesive study using density functional theory simulations is performed to reveal and understand the structural stability, optoelectronic and magnetic properties of Cs2NaMCl6 (M = Mn, Co and Ni) halide double perovskites. The exchange-correlation potential, which is the only unknown parameter in the state-of-the-art formulism is determined through the well-known generalized gradient approximation and integration of the mBJ potential to it. The structural optimization, mechanical stability criteria and tolerance factor confirmed the stability of the double perovskites in a cubic structure with Fm3̄m symmetry. The elastic constants endorsed the mechanical stability and justify the brittle character of these double perovskites. The spin polarized electronic band profile and behaviour of the dielectric constant and absorption coefficient in the spin up and down channels revealed the presence of half-metallic nature in these materials. Moreover, herein, we have discussed the origin of the half-metallic gap and magnetism. The unpaired electrons in the crystal field splitted d-orbitals of the M-sited constituents are responsible for the half-metallic and magnetic character. The total magnetic moment was determined to be 4μB, 4μB and 1μB for the Mn-, Co- and Ni-based double perovskites, respectively, with main contributions solely coming from the transition metal atoms. The perfect spin polarization at the Fermi level suggests the application of double perovskites in spintronic technology.

Ryabochkina, P. A.; Khrushchalina, S. A.; Yurlov, I. A.; Egorysheva, A. V.; Atanova, A. V.; Veselova, V. O.; Kyashkin, V. M.

doi: 10.1039/d0ra04776gpmid: 35519758

We studied the features of the appearance of broadband “white” emission in CaF2-x mol% ErF3 and ZrO2-x mol% Er2O3 (x = 0–25) nanosized dielectric particles upon their excitation by intense laser radiation with λexc = 1550 nm. Comparison of the results of this study with the results obtained previously for other materials doped with Er3+ ions confirmed the thermal nature of the observed emission and made it possible to identify the main factors affecting its occurrence. These include the band gap of the material and the presence of defects in its structure. A method of applying the effect in dermatology is proposed.

Yu, Meihong; Zheng, Yongjie; Tian, Jingzhi

doi: 10.1039/d0ra00274gpmid: 35519735

In this work, polylactic acid/thermoplastic acetylated starch (PLA/TPAS) composites were prepared using PLA as a matrix material and TPAS as a modifier. TPAS is based on acetylated starch, which is plasticized using glycerin. Analysis of the mechanical, thermal, and dynamic mechanical properties, and morphological structures of the PLA/TPAS composites shows that with an increase in the TPAS content, the toughness of the PLA/TPAS composites significantly improves. When the amount of TPAS added is 40% by weight, the elongation at break is increased 4 times. At the same time, the addition of TPAS has little effect on the thermal stability of the composites. Differential scanning calorimetry (DSC), dynamic mechanical analysis and scanning electron microscopy (SEM) analysis results show that PLA is incompatible with TPAS. The addition of TPAS promotes the crystallization of PLA, resulting in a decrease in the thermal stability but limits the degradation behavior during the processing of the material, which has little effect on the performance of the material. High temperature and high humidity soil degradation and ultraviolet radiation aging experiments on PLA/TPAS composites show that the PLA/TPAS composites have good biodegradability. In soil burial degradation experiments, the degradation rate of the pure PLA material is slow, and its final mass retention rate is high. The PLA/TPAS composites degrade fast. In ultraviolet radiation aging experiments, the tensile strength of the PLA/TPAS composites was improved to a certain extent after exposure to ultraviolet radiation. With an increase in the ultraviolet irradiation time, the tensile properties of the PLA/TPAS composites gradually decreased.