RSC Advances

Rozmysłowska-Wojciechowska, A.; Karwowska, E.; Poźniak, S.; Wojciechowski, T.; Chlubny, L.; Olszyna, A.; Ziemkowska, W.; Jastrzębska, A. M.

doi: 10.1039/c8ra07633bpmid: 35520208

The number of investigations regarding the application of 2D nanosheets of MXenes in different technological areas is growing rapidly. Different surface modifications of MXenes have been introduced to date in order to tailor their properties. As a result, surface-modified MXenes could be released in the environment from filtration membranes, adsorbents, or photocatalysts. On the other hand, assessment of their environmental impact is practically unexplored. In the present study, we examined how modification of the antimicrobial Ti3C2 MXene with ceramic oxide and noble metal nanoparticles affects its toxic behavior. The expanded 2D sheets of the Ti3C2 MXene phase were modified with Al2O3/Ag, SiO2/Ag, and SiO2/Pd nanoparticles using the sol–gel method and extensively characterized. The obtained 2D nanocomposite structures were characterized by antibacterial properties. The ecotoxicological assays considered green algae (Desmodesmus quadricauda) as well as two higher plants: sorghum (Sorghum saccharatum) and charlock (Sinapis alba). Our results revealed that obtained nanomaterials can cause both stimulating and inhibiting effects towards algae, and the ecotoxicity depended on the concentration and the type of modification. The study reveals the intriguing property of pristine Ti3C2 which highly stimulated green algae growth at low concentrations. It also shows that modification of pristine Ti3C2 MXene with different nanoparticles changes the ecotoxicological effects of the resulting nanocomposite 2D structures. We have also indicated nanocomposite structures that does not revealed the toxic effect on tested organisms i.e. the Ti3C2 MXene surface-modified with Al2O3/Ag was not phyto- and eco-toxic. This work helps with better understanding of the reactivity of surface-modified MXenes towards chosen organisms, giving more information concerning the potential impact of tested nanocomposites on the ecosystems.

Huang, Tzu-Yen; Yan, Hongping; Abdelsamie, Maged; Savikhin, Victoria; Schneider, Sebastian A.; Ran, Niva A.; Nguyen, Thuc-Quyen; Bazan, Guillermo C.; Toney, Michael F.

doi: 10.1039/c8ra10488cpmid: 35520181

The performance of organic solar cells (OSCs) depends crucially on the morphology in bulk heterojunctions (BHJs), including the degree of crystallinity of the polymer and the amount of each material phase: aggregated donor, aggregated acceptor, and molecular mixed donor : acceptor phase. In this paper, we report the BHJ morphology of as-cast blend films incorporating the polymer PIPCP as the donor and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) as the acceptor. Tracking the scattering intensity of PC61BM as a function of PC61BM concentration shows that PC61BM aggregates into donor-rich domains and there is little to no phase where the PC61BM and PIPCP are intimately mixed. We further find that on blending the scattering peak due to PIPCP ordering along the backbone increases with decreasing PIPCP fraction, which is attributed to improved ordering of PIPCP due to the presence of PC61BM. Our results suggest that the improved ordering of PIPCP along the backbone (consistent with an increased conjugation length) with blending contributes to the observed low open-circuit voltage energy loss.

Gao, Mei; Han, Xiaomin; Sun, Ying; Chen, Hongjiang; Yang, Yun; Liu, Yangyang; Meng, Hui; Gao, Zhihui; Xu, Yanhong; Zhang, Zheng; Han, Jianping

doi: 10.1039/c8ra09409hpmid: 35520206

The main chemical constituents of agarwood are sesquiterpenes and chromones, which can be divided into different categories depending on their molecular skeletons. Agarwoods are obtained from different plant species: Aquilaria sinensis, A. malaccensis, A. crassna, and A. subintegra. In this review, we systematically summarized the structures of 367 compounds isolated from agarwoods originating from four main species. We structurally classified all the components into 11 different types and summarized the number of compounds in each type. Different and identical components were obtained by enumerating the chemical compositions of the different species. Knowledge regarding the chemical constituents of agarwoods of different species will aid understanding of the chemical compositions of agarwoods and will subsequently identify similar compounds that can serve as standards for quality control to provide a reference for future studies on agarwoods from different species and to increase their usefulness.

Wang, Xinxing; Lin, Tiejun; Li, Jie; Yu, Fei; Lv, Dong; Qi, Xingzhen; Wang, Hui; Zhong, Liangshu; Sun, Yuhan

doi: 10.1039/c8ra10477hpmid: 35520170

Direct production of olefins via syngas conversion over a Co2C-based catalyst was investigated in a slurry bed reactor (SBR). It was found that the total selectivities to olefins and oxygenates reached 88.8C% at a CO conversion of 29.5% at 250 °C, 5 bar and H2/CO = 0.5. The hydrocarbon distribution greatly deviated from the classical Anderson–Schulz–Flory (ASF) distribution, with only 2.6C% methane selectivity was obtained. XRD and TEM characterization verified that the Co2C nanoprisms with special exposed facts of (101) and (020) constitutes the Fischer–Tropsch to olefins (FTO) active site. The catalytic activity increased gradually with rising the reaction temperature, while the product distribution almost kept unchanged under various reaction condition in SBR. Compared to the reaction in FBR, the Co2C-based catalyst exhibited relative better catalytic performance during FTO process in SBR. Specifically, a higher CO conversion, a lower methane selectivity and a higher total selectivities to olefins and oxygenates were achieved in SBR. In addition, the catalyst can be in situ reduced in slurry bed reactor at mild temperature (300 °C) and no obvious deactivation was found within nearly 100 h time-on-stream, which suggested a promising route for the direct production of olefins via syngas in industrial application.

Li, Yue-Lan; Zhu, Rong-Xiu; Li, Gang; Wang, Ning-Ning; Liu, Chun-Yu; Zhao, Zun-Tian; Lou, Hong-Xiang

doi: 10.1039/c8ra10329apmid: 35520149

The isolation of the cytotoxic fractions from the endolichenic fungus Ophiosphaerella korrae yielded six new metabolites, including five polyketides (ophiofuranones A (1) and B (2), with unusual furopyran-3,4-dione-fused heterocyclic skeletons, ophiochromanone (3), ophiolactone (4), and ophioisocoumarin (5)), one sesquiterpenoid ophiokorrin (10), and nine known compounds. Their structures were established on the basis of the analysis of HRESIMS and NMR spectroscopic data. ECD calculations, GIAO NMR shift calculations and single-crystal X-ray diffraction were employed for the stereo-structure determination. A plausible biogenetic pathway for the ophiofuranones A (1) and B (2) was proposed. The cytotoxic assay suggested that the five known perylenequinones mainly contributed to the cytoxicity of the extract. Further phytotoxic studies indicated that ophiokorrin inhibited root elongation in the germination of Arabidopsis thaliana with an IC50 value of 18.06 μg mL−1.

Xue, Dongyang; Zhou, Rui; Lin, Xiaoping; Duan, Xiaochuan; Li, Qiuhong; Wang, Taihong

doi: 10.1039/c8ra07365apmid: 35520162

Cr-doped α-Fe2O3 nanoparticles were synthesized by a low-cost and environmentally friendly hydrothermal route. Their gas sensing properties were investigated and the sensor showed high sensitivity and selectivity to H2S gas. Different Cr doping levels from 0 to 8.0 wt% were studied, and the sensor of 4.0 wt% Cr-doped α-Fe2O3 showed the largest response, with a response of 213 to 50 ppm H2S at 100 °C. The incorporation of Cr ions within α-Fe2O3 nanocrystals increases the specific surface area, and promotes the oxidation of H2S and oxygen adsorption in the air. Thus, the doping of Cr into α-Fe2O3 nanostructures would be a promising method for designing and fabricating high performance H2S gas sensors.

He, Kun; Xie, Pu; Zu, Chengkui; Wang, Yanhang; Li, Baoying; Han, Bin; Rong, Min Zhi; Zhang, Ming Qiu

doi: 10.1039/c8ra08401gpmid: 35520197

Solid-state electrolytes have emerged as a promising alternative to existing liquid electrolytes for next-generation flexible Li metal batteries with enhanced safety and stability. Nevertheless, the brittleness and inferior room temperature conductivity are major obstacles for practical applications. Herein, for the first time, we have fabricated a flexible lithium ion conductive glass-ceramic fiber by using a melt-spun homogeneous NASICON-type structured Li1.5Al0.5Ge1.5(PO4)3 (LAGP) glass melt and annealed at 825 °C. The annealed samples exhibited a higher lithium ion conductivity than the air-quenched sample due to the presence of a well-crystallized crystal grain in the annealed sample. Meanwhile, the ionic conductivity has shown an inverse relationship with the diameter of annealed LAGP glass-ceramic fibers. The results revealed that the annealed glass-ceramic fiber, with a diameter of 10 μm, resulted in lithium ion conductivity of 8.8 × 103 S cm−1 at room temperature.

Zhao, Zhendong; Wu, Qianqian; Nie, Tiantian; Zhou, Wenjun

doi: 10.1039/c8ra08544gpmid: 35520176

Atrazine (ATZ) adsorption in two natural soils amended with biochars produced from different feedstocks at 300, 500, and 700 °C were investigated; further, the relationships between the surface and partition adsorption capacities of ATZ in biochar-amended soils with biochar characteristics were quantitatively evaluated. The results revealed that high aromaticity, hydrophobicity, and low polarity of biochar facilitated ATZ adsorption. The addition of selected biochars significantly increased the adsorption of ATZ on paddy soil (PS) and black soil (BS) by 5.2–7.5 times and 2.3–4.2 times, respectively. On the contrary, the degree of increase in surface adsorption was much higher than that in partition adsorption, mainly due to the role of the specific adsorption of ATZ on biochar. Meanwhile, the respective contributions of surface and partition adsorptions to the total ATZ adsorption on biochar-amended soil changed with different addition amounts of biochar. The multiple nonlinear regression analysis demonstrated the linear dependence of H/C ratio, (O + N)/C ratio, and specific surface area (SSA) of biochar on the surface adsorption capacity of biochar-amended PS and BS, as well as the linear dependence of organic carbon and ash contents on the partition adsorption capacity of biochar-amended PS and the linear dependence of the H/C ratio and SSA on the partition adsorption capacity of biochar-amended BS. In biochar-amended soil systems, interactions between biochar and soil could affect ATZ adsorption, and organic matter in biochar might compensate for the role of soil organic matter in the competition for adsorption sites with a decrease in the biochar pyrolysis temperature.

Liu, Hai-Xiao; Li, Lianzhi; Yang, Xin-Zhi; Wei, Chuan-Wan; Cheng, Hui-Min; Gao, Shu-Qin; Wen, Ge-Bo; Lin, Ying-Wu

doi: 10.1039/c8ra10390apmid: 35520156

Human neuroglobin (Ngb) forms an intramolecular disulfide bond between Cys46 and Cys55, with a third Cys120 near the protein surface, which is a promising protein model for heme protein design. In order to protect the free Cys120 and to enhance the protein stability, we herein developed a strategy by designing an additional disulfide bond between Cys120 and Cys15 via A15C mutation. The design was supported by molecular modeling, and the formation of Cys15–Cys120 disulfide bond was confirmed experimentally by ESI-MS analysis. Molecular modeling, UV-Vis and CD spectroscopy showed that the additional disulfide bond caused minimal structural alterations of Ngb. Meanwhile, the disulfide bond of Cys15–Cys120 was found to enhance both Gdn·HCl-induced unfolding stability (increased by ∼0.64 M) and pH-induced unfolding stability (decreased by ∼0.69 pH unit), as compared to those of WT Ngb with a single native disulfide bond of Cys46–Cys55. Moreover, the half denaturation temperature (Tm) of A15C Ngb was determined to be higher than 100 °C. In addition, the disulfide bond of Cys15–Cys120 has slight effects on protein function, such as an increase in the rate of O2 release by ∼1.4-fold. This study not only suggests a crucial role of the artificial disulfide in protein stabilization, but also lays the groundwork for further investigation of the structure and function of Ngb, as well as for the design of other functional heme proteins, based on the scaffold of A15C Ngb with an enhanced stability.

Li, Yuzhou; Zhang, Yufan; Zhang, Haoran; Xing, Tie-ling; Chen, Guo-qiang

doi: 10.1039/c9ra00171apmid: 35520148

In recent years, the energy supply problem of wearable electronic equipment has become a topic of increasing concern. It is necessary to develop energy storage equipment with environmental protection, flexibility, a light quality and excellent performance. In this work, a solid, flexible and symmetrical supercapacitor based on graphene coated cotton fabric was fabricated. The flexible electrode materials were prepared through an environmentally friendly “dry-coating” method and subsequent “two step reduction” method of chemical and microwave reduction, the method is simple and convenient. The morphology and structure of prepared flexible electrode materials were characterized by scanning electron microscopy, X-ray diffraction, and Raman spectrometry. The supercapacitor was assembled in a sandwich structure and packaged and its electrochemical performance was investigated. The flexible sandwich structure (FSS) supercapacitor exhibits high capacitance (464 F g−1 at 0.25 A g−1), good cycling stability (91.6% capacitance retention after 1000 charge and discharge cycles) and excellent electrochemical stability. This supercapacitor with easy fabrication, flexible and excellent electrochemical performance has potential to be used as a wearable device.