High Dispersion Research Articles

Foraging Segregation Between Adult Female Northern Elephant Seals (Mirounga angustirostris) from Guadalupe Island and the San Benito Archipelago, Mexico

Female northern elephant seals (Mirounga angustirostris) are migratory animals that form colonies along the coasts of California and the Baja California Peninsula, Mexico. A recent decline in abundance has been recorded in this species Mexican distribution, which is an important reason to investigate the different ecological processes operating in these colonies. The aim of this study was to determine values of stable isotope ratios (δ13C and δ15N) in pup fur as foraging maternal indicators. During the same breeding season (2015), pup fur samples were collected to investigate these foraging variations between the two major Mexican colonies—Guadalupe Island (GI) and the San Benito Archipelago (SBA). Isotopic areas were built using the ‘SIBER’ package in R, and a custom hierarchical Bayesian model was used to compare the values from both localities. Mean (± standard deviation [SD]) δ13C values for individuals from GI and the SBA were -16.9 ± 0.8‰ and -17.3 ± 0.4‰, respectively, while δ15N values were 17.4 ± 1.1‰ and 16.7 ± 1.1‰, respectively. The difference between the posterior means indicated a high probability (P > 99%) of GI having higher stable isotope ratio values than the SBA. For the posterior SDs, there were highly probable differences (P = 100%) only for δ13C, where GI had a higher dispersion. Such differences explained why GI presented a wider isotopic niche area than the SBA, indicating more diverse foraging habits along GI’s offshore-inshore gradient. Additionally, GI showed higher δ15N values than the SBA. Although this could be related to a slightly higher trophic position for GI individuals, the latitudinal effects of foraging grounds with distinct isotopic baselines remain a plausible explanation for the variations in both isotope ratios, suggesting that individuals from the SBA foraged in a more northerly location than those from GI. This study provides valuable knowledge about how females from both colonies partition resources, especially regarding habitat use.

Hidden Impurities Generate False Positives in Single Atom Catalyst Imaging.

Single-atom catalysts (SACs) are an emerging class of materials, leveraging maximum atom utilization and distinctive structural and electronic properties to bridge heterogeneous and homogeneous catalysis. Direct imaging methods, such as aberration-corrected high-angle annular dark-field scanning transmission electron microscopy, are commonly applied to confirm the atomic dispersion of active sites. However, interpretations of data from these techniques can be challenging due to simultaneous contributions to intensity from impurities introduced during synthesis processes, as well as any variation in position relative to the focal plane of the electron beam. To address this matter, this paper presents a comprehensive study on two representative SACs containing isolated nickel or copper atoms. Spectroscopic techniques, including X-ray absorption spectroscopy, were employed to prove the high metal dispersion of the catalytic atoms. Employing scanning transmission electron microscopy imaging combined with single-atom-sensitive electron energy loss spectroscopy, we scrutinized thin specimens of the catalysts to provide an unambiguous chemical identification of the observed single-atom species and thereby distinguish impurities from active sites at the single-atom level. Overall, the study underscores the complexity of SACs characterization and establishes the importance of the use of spectroscopy in tandem with imaging at atomic resolution to fully and reliably characterize single-atom catalysts.

Intra- and interspecies variation and population dynamics of Fasciola gigantica among ruminants in Sudan.

Fasciola gigantica is a widespread parasite that causes neglected disease in livestock worldwide. Its high transmissibility and dispersion are attributed to its ability to infect intermediate snail hosts and adapt to various mammalian definitive hosts. This study investigated the variation and population dynamics of F. gigantica in cattle, sheep, and goats from three states in Sudan. Mitochondrial cytochrome c oxidase subunit I (COI) and NADH dehydrogenase subunit 1 (ND1) genes were sequenced successfully to examine intra and interspecific differences. ND1 exhibited higher diversity than COI, with 15 haplotypes and 10 haplotypes, respectively. Both genes had high haplotype diversity but low nucleotide diversity, with 21 and 11 polymorphic sites for ND1 and COI, respectively. Mismatch distribution analysis and neutrality tests revealed that F. gigantica from different host species was in a state of population expansion. Maximum likelihood phylogenetic trees and median networks revealed that F. gigantica in Sudan and other African countries had host-specific and country-specific lineages for both genes. The study also indicated that F. gigantica-infected small ruminants were evolutionarily distant, suggesting deep and historical interspecies adaptation.

Keplerate-Type Polyoxometalates-Based Triboelectric Nanogenerator for Higher Performance via the Morphology Modulation of Blackberry Structure.

The triboelectric material is the key factor affecting the performance of triboelectric nanogenerators (TENGs). Inorganic materials have higher heat resistance and stability than widely used organic materials. However, the weaker triboelectric property limits the application of TENGs. Modulating surface roughness by changing particle shape and size is a simple way to increase performance for TENGs. Polyoxometalates (POMs) have unrivalled structural diversity and can self-assemble to form different nanostructures. In this study, we propose [{(NH4)42[Mo72VIMo60VO372(CH3COO)30(H2O)7.ca.300H2O.ca.CH3COONH4)]}-Mo132] and [{Na8K14(VO)2[{(MoVI)(Mo5VIO21)(H2O)3]}10{(MoVI)Mo5VIO21(H2O)3(SO4)}2{VIVO(H2O)20}{VIVO}10({KSO4}5)2]·150H2O)}-Mo72V30] with blackberry structure which are cured and prepared into film by spin-coating technique, are used as triboelectric positive materials for the first time in the field of TENGs. Keplerate-type polyoxometalates can form blackberry structures with higher dispersibility and flexibility, which can be used to control surface roughness by regulating the size of particles. The discovery proves that the particle size influences the surface roughness, which adjusts the output of TENGs. According to our findings, Mo132-h-TENG generates an output voltage of 29.3 V, an output charge of 8 nC 2-3 folds higher than Mo132-TENG, and a maximum power density of 6.25 mW·m-2 at 300 MΩ. Our research provides that altering the dimensional size can be an available way to raise the output of TENGs.

Amidoximated‐Wood Derived Carbons as Advanced Self‐Standing Electrodes for Supercapacitor and Water Splitting

AbstractWood‐derived carbons demonstrate great potential as self‐standing electrodes in energy storage/conversion applications, including supercapacitors and water‐splitting devices. However, the key challenge remains the rational customization of surface functionalities for optimized performance. This study introduces an innovative approach to self‐standing wood‐derived carbons with tailored nitrogen and metal functionalities. In contrast to traditional impregnation techniques, which offer limited precision in surface modification, this approach entails the intentional attachment of amidoxime groups to the wood substrates. These groups serve as nitrogen sources, and create abundant surface anchoring sites for metal ions due to the chelation between the amidoxime groups and metals. The resulting carbons feature uniform and high dispersion of nitrogen and metal functionalities, along with a distinctive hierarchical porosity combining interconnected open channels with abundant mesopores. As a proof‐of‐concept, different metals are incorporated (i.e., Mn, Co, Ni) into the amidoximated‐wood precursors, and the resulting self‐standing carbons showcase excellent performance in both supercapacitors and water‐splitting applications. Leveraging the specific chelating ability of amidoxime groups toward metal ions, this strategy holds great potential as a generic approach to systematically tailoring the surface functionalities of carbon‐based materials for various electrochemical energy storage/conversion processes.

A modified truss-arch model for shear strength evaluation of corroded reinforced concrete columns

Under seismic loading, corroded reinforced concrete (RC) columns are prone to brittle shear failure, which poses a significant threat to existing structures. However, due to the mechanical defects and insufficient parameters included in the equations available in codes, the literature exhibits a lack of precision in predicting the shear strength of such columns. In this paper, a shear strength equation for the RC column was established based on the truss-arch model theory. On this basis, the effect of corrosion on key parameters such as the cross-sectional area of rebar, yield strength, compressive strength of concrete, and displacement ductility was fully considered to establish the shear strength equation of corroded RC columns. To assess the accuracy and applicability of the proposed equation, a database consisting of 215 specimen parameters was compiled. Comparative analyses were conducted with existing equations from the literature. The results indicate that the mean values and coefficient of variation for the ratio of calculated values to the tested values of the equation were 1.098 and 0.601, respectively, which proves the equation’s high computational accuracy and low dispersion. Consequently, the proposed equation offers a more effective calculation method for predicting and assessing the shear strength of corroded RC columns. This method holds significant potential for enhancing the resilience of structures in seismic-prone regions.

A Tape-Wrapping Strategy towards Electrochemical Fabrication of Water-Dispersible Graphene.

Graphene has achieved mass production via various preparative routes and demonstrated its uniqueness in many application fields for its intrinsically high electron mobility and thermal conductivity. However, graphene faces limitations in assembling macroscopic structures because of its hydrophobic property. Therefore, balancing high crystal quality and good aqueous dispersibility is of great importance in practical applications. Herein, we propose a tape-wrapping strategy to electrochemically fabricate water-dispersible graphene (w-Gr) with both excellent dispersibility (~4.5 mg/mL, stable over 2 months), and well-preserved crystalline structure. A large production rate (4.5 mg/min, six times faster than previous electrochemical methods), high yield (65.4% ≤5 atomic layers) and good processability are demonstrated. A mechanism investigation indicates that the rational design of anode configuration to ensure proper oxidation, deep exfoliation and unobstructed mass transfer is responsible for the high efficiency of this strategy. This simple yet efficient electrochemical method is expected to promote the scalable preparation and applications of graphene.

Efficient catalysis of acetylene semi-hydrogenation through synergistic action of supported ionic liquid-nickel catalyst

In the semi-hydrogenation of acetylene, nickel-based catalysts offer a promising alternative to precious metal palladium catalysts. Despite the positive hydrogenation activity of nickel-based catalysts, there is still room for improvement in terms of their selectivity and stability. In this study, a simple incipient wetness impregnation method was employed to prepare Ni(OAC)2-IL/Al2O3 catalyst and its performance in the selective hydrogenation of acetylene was investigated. It was found that under the conditions of 170 °C and a space velocity of 600 h−1, the 3 % Ni(OAC)2-IL/Al2O3 catalyst achieved a 95.3 % acetylene conversion with an 85.6 % ethylene selectivity. Furthermore, the catalyst exhibited outstanding stability over a 100 hour test. TEM, XPS and C2H4-TPD experiments showed that the Ni species were encapsulated in the ionic liquids (ILs), and the interaction between the metal ions, nickel, and the ILs ensured a high dispersion and stability of the actives on the carriers, and the electronic effect between the ionic nickel and the ionic liquids increased the electron cloud density of the Ni, which improved the catalyst selectivity, which is the main reason for its excellent catalytic performance.

Synthesis and characterization of α-(4-(2,3-hydroxylpropoxy)phenylimino)-o-cresol Schiff base as an effective UV-absorber for ink systems

Schiff base is a diverse group of organic compounds and has potential as a UV absorber for ink systems due to its high UV protection, simple synthesis, and high dispersion in organic matrices. In this work, a novel Schiff base α-(4-(2,3-dihydroxylpropoxy)phenylimino)-o-cresol (named GMA-I) was synthesized and investigated as a UV absorber for ink system. The UV-protection of GMA-I was evaluated on ink-coated duplex substrate samples via color measurement using an accelerated UV test chamber. The results showed that the GMA-I exhibited strong absorption in both UVA and UVB regions with an extra high molar absorption coefficient of 43,554 M−1 cm−1, and high thermal stability of 271.4 °C. Interestingly, the GMA-I showed high UV protection for ink platform at low content of 2 wt% thank to the intramolecular proton transfer mechanism and therefore potential as a UV absorber additive for ink systems.

Nanoplastics enhance the stability of kaolinite and affect the sorption of Pb2+ in aquatic environments

The heteroaggregation of nanoplastics with minerals has been widely investigated. However, few studies have focused on the interaction between similar negatively charged clay minerals and nanoplastics, especially how their interactions affect the migration of heavy metals. This study investigated heteroaggregation of kaolinite (a model of natural mineral) with polystyrene nanoplastics (PSNPs) and the effect of heteroaggregates on lead (Pb2+) sorption. Dynamic light scattering (DLS) measurement highlighted that PSNPs owned higher colloidal stability than kaolinite in aquatic environments. Due to the surface charge heterogeneity of kaolinite, the heteroaggregation behavior between kaolinite and PSNPs was highly pH-dependent. At pH 3.0 and 6.0, kaolinite particles with positively charged edge surfaces favored the association of PSNPs. PSNPs were found to be primarily attached on the kaolinite edge (010) surface, followed by Al-terminated (001) and Si-terminated (00 1¯) surfaces based on density functional theory (DFT) calculations. At pH 10.0, they had negligible interaction due to the strong electrostatic repulsion. Interestingly, kaolinite carried more negative charges after heteroaggregation with PSNPs, resulting in slower edge-to-face homoaggregation and higher dispersibility, and thus increasing the sorption capacity for Pb2+. This investigation provided a new understanding of nanoplastics interactions with negatively charged minerals and highlighted the vital role of nanoplastics in mineral stability and contaminant migration.

Wave setup estimation at regional scale: Empirical and modeling-based multi-approach analysis in the Mediterranean Sea

Wave setup is a physical process that induces a temporal increase of the mean water level due to wave dissipation by bottom friction and breaking in the surf zone, extending over tens to hundreds of meters in the cross-shore direction. Wave setup contribution to coastal sea level solely induced by wind and atmospheric effects can increase by more than 100% under extreme events and conditions favouring its formation. It is therefore crucial to consider this phenomenon when assessing sea-level-related coastal hazards. Previous studies estimated the wave setup effect by means of numerical modeling and empirical formulations at regional and global scale. Such analyses require either high computational capacity to implement high-resolution numerical models over large domains, and/or accurate information on coastal morphological features from global or regional databases. Although the Mediterranean Sea is a fetch-limited environment, waves generated from extra-tropical cyclones are powerful enough for wave setup to develop, and subsequently for a potential significant wave setup contribution to extreme coastal sea level. Through the use of both numerical and empirical methods, we investigate the uncertainty associated to wave setup representation on the frequency and magnitude of coastal extreme sea levels occurring on sandy beaches in the Mediterranean Sea. Wave setup values are compared at beach scale between process-based modeling and empirical approaches, showing highly variable results. We also quantify the impact of wave setup on return levels of coastal sea level extremes using reconstructed sea levels. We employ various methods to calculate the wave setup component. Results show high spatial dispersion, with clear differences between the numerical and empirical approaches, especially in regions prone to the development of energetic waves. The total inter-method dispersion of 100-year return levels is often higher than 30 cm for average values of 62.4 cm. We emphasize the important limitations related to wave setup modeling (i.e., its underestimation) at large scale, and call for caution when applying empirical formulations (generally developed from local studies) at regional to global scale, which can lead to unrealistic wave setup values.

Investigating the Drivers of Electron Temperature Variations in H ii Regions with Keck-KCWI and VLT-MUSE

H ii region electron temperatures are a critical ingredient in metallicity determinations, and recent observations have revealed systematic variations in the temperatures measured using different ions. We present electron temperatures (T e ) measured using the optical auroral lines ([N ii]λ5756, [O ii]λ λ7320, 7330, [S ii]λ λ4069, 4076, [O iii]λ4363, and [S iii]λ6312) for a sample of H ii regions in seven nearby galaxies. We use observations from the Physics at High Angular resolution in Nearby Galaxies survey (PHANGS) obtained with integral field spectrographs on Keck (Keck Cosmic Web Imager) and the Very Large Telescope (Multi-Unit Spectroscopic Explorer). We compare the different T e measurements with H ii region and ISM environmental properties such as electron density, ionization parameter, molecular gas velocity dispersion, and stellar association/cluster mass and age obtained from PHANGS. We find that the temperatures from [O ii] and [S ii] are likely overestimated due to the presence of electron density inhomogeneities in H ii regions. We measure high [O iii] temperatures in a subset of regions with high molecular gas velocity dispersion and low ionization parameter, which may be explained by the presence of low-velocity shocks. In agreement with previous studies, the T e–T e between [N ii] and [S iii] temperatures have the lowest observed scatter and follow predictions from photoionization modeling, which suggests that these tracers reflect H ii region temperatures across the various ionization zones better than [O ii], [S ii], and [O iii].

Reactive extrusion fabrication of thermoplastic starch with Ca2+ heterodentate coordination structure for harvesting multiple-reusable PBAT/TPS films

Creating multiple-reusable PBAT/TPS (PT) films presents a novel solution to reduce carbon emissions from disposable packaging, addressing challenges like the high creep of PBAT and the glycerol migration of TPS. Consequently, adopting reactive extrusion to fabricate reversible cross-linking TPS with high shape memory performance, low migration, and homogeneous dispersion in PBAT matrix was a fascinating strategy. Herein, starch, glycerol and CaCl2 (calcium chloride) were extruded to fabricate TPS-Ca with Ca2+ heterodentate coordination structure and confirmed by XPS, 1H NMR and temperature-dependent FTIR. The results of DMA, dynamic rheology, flow activation energy and SEM revealed that TPS-Ca exhibited significant temperature-sensitive reversible properties and robust melt flow capability, enabling micro-nano scale dispersion in PBAT. Noteworthy, PBAT/TPS-Ca (PT-Ca) would recover 100 % length within 20 s by microwave heating after being loaded under the hygrothermal environment. Meanwhile, the migration weight of glycerol decreased from 2.5 % to 1.2 % for the heat-moisture-treated PBAT/TPS (HPT) and PBAT/TPS-Ca (HPTCa). Remarkably, the tensile strength and elongation at the break of HPT-Ca increased to 20.0 MPa and 924 %, respectively, due to reduced stress concentration sites in the phase interface. In summary, our study provides a streamlined strategy for fabricating multiple-reusable PT, offering a sustainable solution to eliminate carbon emissions linked to disposable plastic.

Preparation of Bi4Ti3O12/TiO2 by flame spray pyrolysis for photoelectrocatalytic degradation of tetracycline

The negative effects of the irrational use of antibiotics have been increasing attention from the public, making it urgently needed to develop effective techniques for removing antibiotics from wastewater. Simultaneously, the construction of heterogeneous TiO2 photoanodes can be used to enhance photoelectrocatalytic performance. Herein, we used an advanced method, namely one-step flame spray pyrolysis (FSP) to in-situ prepare Bi4Ti3O12/TiO2 heterostructures. The ultra-high temperature characteristics of this method facilitated the high dispersion of Bi species on TiO2, leading to the formation of the Bi4Ti3O12 phase within milliseconds. Bi4Ti3O12 forms a "Z" type heterojunction with TiO2, improving charge separation and enhancing electron transfer efficiency. The photoeletrocatalytic degradation effect of Bi4Ti3O12/TiO2 on tetracycline is significantly improved. Under simulated sunlight irradiation for 75 min and 1V voltage, the removal of tetracycline can reach 99.7%. The recycling degradation experiments demonstrated the remarkable reusability and stability of Bi4Ti3O12/TiO2, while the evaluation of degradation intermediates and toxicity analysis of tetracycline were also conducted. Furthermore, free radical trapping experiments confirmed that hydroxyl radicals and holes play a significant role in the removal of tetracycline.

Experimental and theoretical studies on effective synergistic low-temperature removal of NO and typical volatile organic compounds (VOCs) from flue gas based on Cu@VWTi catalyst

The transition metal-modified VWTi structural catalysts hold great promise for simultaneously removing nitrogen oxides (NOx) and volatile organic compounds (VOCs) from industrial flue gases. A series of Cu@VWTi catalysts were prepared to investigate their synergistic low-temperature removal performance towards NO and typical VOCs, including toluene, benzene, chlorobenzene (CB), p-chlorotoluene (p-CT), and dichloromethane (DCM). The copper-enhanced samples prepared via ultrasound-assisted impregnation exhibited irregular globular and varying crystallinity. The catalysts displayed a typical anatase crystal structure with high TiO2 content or high dispersion of V and W species along with a certain adjustment effect on the morphology. Various controlling factors affecting the synergistic removal of NO and VOCs were evaluated. It was observed that the presence of VOCs in flue gas has weak impact on NO removal, except for the waste incineration using the Cu@VWTi catalyst. However, a high initial NO concentration had an adverse effect on VOCs removal. Impressively, the optimized copper-doped catalyst (5wt% Cu loaded of smelting plant and coal-fired power plant used catalyst) exhibited excellent performance for p-CT, toluene and DCM removal of 95.0%, 99.6% and 100% at 300 °C, respectively. The toluene and p-CT conversion efficiencies were highest over the catalyst used in the smelting plant after Cu loading, surpassing the benzene conversion efficiency. Cu@VWTi demonstrated excellent performance for p-CT, toluene, and DCM removal at 250 °C. Although 5wt% Cu loading on the catalysts significantly enhanced the stability and anti-jamming of VOCs removal, as well as their tolerance to both SO2 and water vapor. The enhanced mechanism of Cu decoration attributed to the enhanced intensity of acid sites and the stable relative proportion of Oads/Olatt species in the used 5% Cu loaded catalyst due to the redox cycles of Cu and V species. Compared with Brønsted acid, which primarily adsorbs NH4+, Lewis acid mainly adsorbs gas phase acid and forms coordinated NH3 in gas phase. The bonding between toluene and the Cu site was enhanced with an adsorption energy of -130.9 kJ·mol-1, as well as the cracking adsorption of the CH2Cl2 on the Ti site with a bonding energy of -436.7 kJ·mol-1, both indicating strong chemical adsorption. The first step of dechlorination and demethylation was thermodynamically and kinetically favorable for DCM and toluene decomposition.

Constraining on the non-standard cosmological models combining the observations of high-redshift quasars and BAO

In this work, we studied four types of cosmological models with different mechanisms driving the accelerated expansion of the universe, include Braneworld models, Chaplygin Gas models, Emergent Dark Energy models, and cosmological torsion models. Considering that the dynamics of these models at low redshifts are very similar and difficult to distinguish, we used the latest and largest UV and X-ray measurements of quasars (QSOs) observations covering the range of redshift 0.009<z<7.5\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$0.009<z<7.5$$\\end{document}. However, the high intrinsic dispersion of this sample and the degeneracy between cosmological model parameters, we added 2D-BAO and 3D-BAO datasets to help us constrain the parameters of these cosmological models. Our results suggest that standard cold dark matter scenario may not be the best cosmological model preferred by the high-redshift observations. The Generalized Chaplygin Gas (GCG) and cosmological constant plus torsion (named Case II) models perform best by Akaike Information Criterion (AIC), but the Λ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Lambda $$\\end{document}CDM is the best cosmological model preferred by Bayesian Information Criterion (BIC). Our work also supports that the Phenomenologically Emergent Dark Energy and cosmological torsion models may alleviate the Hubble tension, the reported value of the Hubble constant obtained from QSO+BAO datasets combination lies between Planck 2018 observations and local measurements from the SH0ES collaboration, while other cosmological models all support that the Hubble constant tends to be closer to recent Planck 2018 results, but these model are penalized by information criterion.

Catalytic Hydroconversion of Lauric Acid Over Poly(N-vinyl-2-pyrrolidone)-Coated Pd Nanoparticles on ZIF-8

A subclass of Metal-Organic Frameworks, Zeolitic Imidazole Frameworks-8 (ZIF-8) is known as an emerging material that has the characteristic of a large surface area, good thermal stability as well as a high porosity. Instead of having extraordinary properties, ZIF-8 consists of Lewis acid and Lewis base site on its Zn metals and 2-methylimidazole which are the important components for the catalyst. In this study, Pd-Poly(N-vinyl-2-pyrrolidone) coated on ZIF-8 (Pd-PVP@ZIF-8) was synthesized by mixed Pd-PVP solution and ZIF-8 precursors at room temperature. The Pd-PVP solution was varied from 10 to 50 ml to differentiate the Pd concentration in ZIF-8. As-synthesized 50 ml of Pd-PVP on ZIF-8 (50Pd-PVP@ZIF-8) showed catalytic activity in the conversion of 98.6% lauric acid to produce 78.2% of 1-dodecanol at optimum condition 320 °C for 6 h. The synergy between Pd-PVP as metal and ZIF-8 as metal support as well as high dispersion of Pd particles could enhance performance in the conversion of lauric acid. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Catalytic Hydrogenation of γ-Butyrolactone to Butanediol over a High-Performance Cu-SiO2 Catalyst

High-performance Cu catalysts were developed for the selective hydrogenation of γ-butyrolactone (GBL) to 1,4-butanediol (BDO). Among the various catalysts prepared by ammonia evaporation (AE) and impregnation (IM) methods with silica or MFI zeolite supports, the 5% Cu-SiO2-AE catalyst was the best one. It exhibited 95% selectivity for BDO and 71% conversion of GBL after 2–8 h reaction at 200 °C and 4 MPa H2, with high stability in five-cycle runs. Comprehensive characterizations showed that the AE method favored generating nano Cu particles with an average size of 2.9 nm on the 5% Cu-SiO2-AE catalyst. The silica support derived from a sol demonstrated an advantage over the MFI zeolite in the preparation of a highly dispersed and stable Cu catalyst, in view of its anti-sintering and robust composition of Cu0, Cu+, and Cu2+ in the cycling operation. The reaction pathways for GBL to BDO over the Cu catalysts were found to commonly involve reversible reactions of hydrogenation and dehydrogenation, along with subsequent dehydration to form THF. The high performance of the Cu catalysts in the conversion of GBL to BDO was attributed to the high dispersion of Cu, the presence of stable active sites, and fewer strong acid sites in the catalyst.

Titania nanoparticles finishing for smart leather surface

This study focuses on the synthesis and characterization of nanoparticles, specifically titanium dioxide (TiO2) with a uniform size of approximately 5–8 nm in diameter. The nanoparticles exhibit high dispersibility and stability in hydrophilic environments. Notably, nitrogen-doped nanoparticles demonstrate intriguing self-cleaning properties, as evidenced by the degradation of methylene blue stain under UV light. Rutile nanoparticles stabilize color and color fastness in the presence of anatase-covered surfaces. Anti-mold tests reveal enhanced antimicrobial properties of the surfaces containing titania NPs when functionalized with polyethylene glycol (PEG). Ascorbic acid functionalized nanoparticles show promising behavior, encouraging the exploration of nanoparticle functionalization for property improvement. Leather samples coated with nanoparticles undergo abrasion, wear, and scratch resistance tests. The nanoparticles significantly enhance abrasion resistance, doubling the resistance. This suggests the potential for nanoparticle-based finishing to improve fastness to dry and wet rubbing, reducing defects in the coating.

Preparation and Properties of Polycarboxylate Superplasticizer Based on Chain Transfer Agents with Various Structures

AbstractPolycarboxylate superplasticizer (PCE) is a common admixture in high performance concrete. In the design of PCE molecules, it is necessary to ensure that the molecular weight of the polymer is moderate and the acid‐ether ratio is appropriate to improve the dispersion effect. Chain transfer agent is usually added in the synthesis of PCE to adjust the molecular weight and distribution of PCE. In this study, three sulfhydryl chain transfer agents with different electron‐withdrawing groups or electron‐donating groups were synthesized by nucleophilic addition reaction based on sodium hydrosulfide method. Then, three kinds of PCE containing sulfhydryl chain transfer agent were prepared and compared with commercial β‐mercaptopropionic acid superplasticizers. The yield stress and plastic viscosity of cement paste samples prepared by PCE−A and PCE−M were close to those prepared by PCE−P. PCE−M and PCE−A prepared by chain transfer agent with electron‐withdrawing group had higher dispersion and retention capacity than PCE−P, and had more obvious delay of cement hydration and lower hydration accumulated heat. Therefore, the optimization of molecular structure of chain transfer agent is helpful to improve the properties of concrete superplasticizer.