Investigating the Electrochemical Performance of MnFe2O4@xC Nanocomposites as Anode Materials for Sodium-Ion Batteries.

Transition metal oxides (TMOs) are important anode materials in sodium-ion batteries (SIBs) due to their high theoretical capacities, abundant resources, and cost-effectiveness. However, issues such as the low conductivity and large volume variation of TMO bulk materials during the cycling process result in poor electrochemical performance. Nanosizing and compositing with carbon materials are two effective strategies to overcome these issues. In this study, spherical MnFe2O4@xC nanocomposites composed of MnFe2O4 inner cores and tunable carbon shell thicknesses were successfully prepared and utilized as anode materials for SIBs. It was found that the property of the carbon shell plays a crucial role in tuning the electrochemical performance of MnFe2O4@xC nanocomposites and an appropriate carbon shell thickness (content) leads to the optimal battery performance. Thus, compared to MnFe2O4@1C and MnFe2O4@8C, MnFe2O4@4C nanocomposite exhibits optimal electrochemical performance by releasing a reversible specific capacity of around 308 mAh·g-1 at 0.1 A·g-1 with 93% capacity retention after 100 cycles, 250 mAh·g-1 at 1.0 A g-1 with 73% capacity retention after 300 cycles in a half cell, and around 111 mAh·g-1 at 1.0 C when coupled with a Na3V2(PO4)3 (NVP) cathode in a full SIB cell.

Research on the energy transition pathways of the transportation sector in the Guangdong-Hong Kong-Macao Greater Bay Area, China.

Energy transitions is an effective way to achieve sustainable development in the transportation sector. To explore the pathways to energy transitions in the Guangdong-Hong Kong-Macao Greater Bay Area (GBA) transportation sector, the article evaluated the potential of energy savings and CO2 emission reduction of different measures in a quantitative way, based on the long-range energy alternatives planning (LEAP) platform. The marginal abatement cost curves are used to visually reflect the cost-benefit of these measures, and to develop cost-effective pathways to energy transitions. The results show that the measures of transportation modes adjustment and private cars regulating should be prioritized due to the potential of significant emission reduction with good cost-effectiveness. The measures of promoting electricity and hydrogen energy have large emission reduction potential, but only those for road traffic are cost-effective, and should be treated with a lower priority. Considering the high cost, the measures of promoting biofuel should be implemented as least priority. Moreover, the measures of liquefied natural gas (LNG) application have good cost-effectiveness, as opposed to limited CO2 emission reduction potential. It can only be used as a transitional fuel for the energy transitions. The findings and research methodology will provide theoretical support for the formulation of transportation energy transition pathways in the GBA and other regions.

Regional Inversion of Soil Heavy Metal Cr Content in Agricultural Land Using Zhuhai-1 Hyperspectral Images.

With the development of hyperspectral imaging technology, the potential for utilizing hyperspectral images to accurately estimate heavy metal concentrations in regional soil has emerged. Currently, soil heavy metal inversion based on laboratory hyperspectral data has demonstrated a commendable level of accuracy. However, satellite images are susceptible to environmental factors such as atmospheric and soil background, presenting a significant challenge in the accurate estimation of soil heavy metal concentrations. In this study, typical chromium (Cr)-contaminated agricultural land in Shaoguan City, Guangdong Province, China, was taken as the study area. Soil sample collection, Cr content determination, laboratory spectral measurements, and hyperspectral satellite image collection were carried out simultaneously. The Zhuhai-1 hyperspectral satellite image spectra were corrected to match laboratory spectra using the direct standardization (DS) algorithm. Then, the corrected spectra were integrated into an optimal model based on laboratory spectral data and sample Cr content data for regional inversion of soil heavy metal Cr content in agricultural land. The results indicated that the combination of standard normal variate (SNV)+ uninformative variable elimination (UVE)+ support vector regression (SVR) model performed best with laboratory spectral data, achieving a high accuracy with an R2 of 0.97, RMSE of 5.87, MAE of 4.72, and RPD of 4.04. The DS algorithm effectively transformed satellite hyperspectral image data into spectra resembling laboratory measurements, mitigating the impact of environmental factors. Therefore, it can be applied for regional inversion of soil heavy metal content. Overall, the study area exhibited a low-risk level of Cr content in the soil, with the majority of Cr content values falling within the range of 36.21-76.23 mg/kg. Higher concentrations were primarily observed in the southeastern part of the study area. This study can provide useful exploration for the promotion and application of Zhuhai-1 image data in the regional inversion of soil heavy metals.

Vein-Like Ni-BTC@Ni3S4 with Sulfur Vacancy and Ni3+ Fabricated In Situ Etching Vulcanization Strategy for an Electrochemical Sensor of Dopamine.

In this study, a novel Ni-BTC@Ni3S4 composite was fabricated by solvothermal reaction using an in situ etching vulcanization strategy and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), and Brunauer-Emmett-Teller (BET) analyses. The existence of a sulfur vacancy and Ni3+ in the as-prepared vein-like Ni-BTC@Ni3S4 greatly promoted the electrochemical sensing activity of the materials. Herein, a simple electrochemical sensor (Ni-BTC@Ni3S4/CPE) has been fabricated and used for the detection of dopamine (DA). The current signal of the Ni-BTC@Ni3S4/CPE-modified electrode was linear with the concentration of DA in the range of 0.05-750 µM (R2 = 0.9995) with a sensitivity of 560.27 µA·mM-1·cm-2 and a detection limit of 0.016 µM. At the same time, the sensor has good stability and anti-interference ability. This study could provide a new idea and strategy for the structural regulation of composite electrode-modified materials and sensitive sensing detection of small biological molecules.

Nonlinear Effects of the Built Environment on Light Physical Activity among Older Adults: The Case of Lanzhou, China.

The aging of the population is increasing the load on the healthcare system, and enhancing light physical activity among older adults can alleviate this problem. This study used medical examination data from 1773 older adults in Lanzhou city (China) and adopted the random forest model to investigate the effect of the built environment on the duration of light physical activity of older adults. The results showed that streetscape greenery has the most significant impact on older adults' light physical activity; greenery can be assessed in a hierarchy of areas; population density and land-use mix only have a positive effect on older adults' light physical activity up to a certain point but a negative effect beyond that point; and a greater distance to the park within 1 km is associated with a longer time spent on light physical activity. Therefore, we conclude that the built environment's impact is only positive within a specific range. Changes in the intervention of environmental variables can be observed visually by calculating the relative importance of the nonlinearity of built environment elements with partial dependency plots. These results provide a reasonable reference indicator for age-friendly community planning.

Differences in the Correlation between the Built Environment and Walking, Moderate, and Vigorous Physical Activity among the Elderly in Low- and High-Income Areas.

Studies have proved that activity and fitness behaviors are closely related to the quality of life and health status of the elderly. However, different intensities of physical activity (PA)-walking, moderate PA, and vigorous PA-have different correlations with the built environment (BE). This study combines the high and low socioeconomic status (SES) of Guangzhou to establish two types of BE models. The physical activity time of 600 elderly people was collected from questionnaires. Through ArcGIS software, 300 m, 500 m, 800 m, and 1000 m buffer zones were identified, and the land use diversity, street design, population density, distance to destination, distance to public transportation-the five Ds of the BE-were measured. SPSS software was adopted to analyze the correlation between the BE and PA. Results: The PA of people living in low-SES areas was more dependent on the BE, whereas the correlation may be limited in high SES areas. Moreover, in low SES areas, walking was negatively correlated with street connectivity; moderate PA was positively correlated with street connectivity and the shortest distance to the subway station, but negatively correlated with the density of entertainment points of interest (POIs). Studying the relevant factors of the environment can propose better strategies to improve the initiative of the elderly to engage in PA.

Evaluating Green Innovation Efficiency and Its Socioeconomic Factors Using a Slack-Based Measure with Environmental Undesirable Outputs.

Understanding green innovation efficiency (GIE) is crucial in assessing achievements of the current development strategy scientifically. Existing literature on measuring green innovation efficiency with considering environmental undesirable outputs at the city level is limited. Consulting existing studies, this paper constructs an evaluation index system to measure green innovation efficiency and its socioeconomic impact factors. Employing a super slacks-based measure (Super-SBM) model, which takes into account undesirable outputs (industrial wastewater emissions, industrial exhaust emissions and CO2 emissions), and a Global Malmquist-Luenberger index (GML), we calculate the green innovation efficiency of 15 cities in the Pearl River Delta (PRD) urban agglomeration from 2009 to 2017, exploring the impact factors behind green innovation efficiency using a Tobit panel regression model. The empirical results are as follows: Due to the heterogeneity of urban functional division and economic development in the Pearl River Delta, more than half of the region's cities were found to be in ineffective or transitional states with respect to their green innovation efficiency. A GML decomposition index shows that technological efficiency and technological progress are out of step with one another in the Pearl River Delta, an asymmetry which is restricting regional green innovation growth. The influencing factors of industrial structure, the level of economic openness, and the urban informationization level are shown to have promoted green innovation efficiency in the Pearl River Delta's cities, while government R&D expenditure and education expenditure exerted negative effects. This paper concludes by highlighting the importance of cooperation between the government and enterprises in achieving green innovation.

Eye-Level Street Greenery and Walking Behaviors of Older Adults.

Evidence suggests that built environment characteristics affect older adults' travel activity behaviors, e.g., walking and cycling, which have well-established health benefits. However, the relationship between urban greenery and walking behaviors remains unclear, partly due to methodological limitation. Previous studies often measured urban greenery from a bird's eye perspective, which may mismatch with the pedestrian's perception from the street. In this study, we measured greenery view index from eye-level streetscape photos retrieved from Baidu Street View, an online mapping service provider. Walking behaviors of 180 older adults in six neighborhoods were collected from questionnaires. We also measured land use diversity, pedestrian-oriented design (street connectivity), and population density-the three Ds of the built environment. Results show that street greenery view index contributes to walking time of older adults, suggesting street greenery should be taken into design consideration to promote walking behaviors of older adults.

The surface plasmon resonance, thermal, support and size effect induced photocatalytic activity enhancement of Au/reduced graphene oxide for selective oxidation of benzylic alcohols.

Reduced graphene oxide (RGO) as an electron-conductive medium and photosensitizer have been widely used to construct efficient RGO/semiconductor photocatalysts for solar energy conversion; however, the role of RGO has been largely underestimated. Herein, the surface plasmon resonance (SPR) effect, thermal effect, support effect, and size effect of Au/RGO are demonstrated to play important roles in enhancing the photocatalytic activity, which has not been considered previously. Au/RGO nanocomposites, synthesized via a facile wet chemistry route, exhibit an excellent visible light photocatalytic performance for selective oxidation of benzylic alcohols. A collection of joint techniques and control experiments have been employed to explain the SPR effect, thermal effect, support effect, and size effect over the Au/RGO photocatalyst. The possible reaction mechanism for the photocatalytic and thermocatalytic selective oxidation of alcohols over Au/RGO has also been discussed.

Facile one-pot fabrication of Ag@MOF(Ag) nanocomposites for highly selective detection of 2,4,6-trinitrophenol in aqueous phase.

Ag@MOF(Ag) nano-composites were fabricated through one-pot facile reflux reaction from the raw materials of AgNO3 and 2-aminoterephthalic acid, and were then characterized through SEM, TEM, XRD, XPS, and FTIR, which showed a high fluorescence quantum yield (10.6%) and exhibited outstanding selectivity and excellent sensitivity for 2,4,6-trinitrophenol (TNP) over a concentration range of 1-29µM in water. The fluorescence quenching mechanism may be attributed to hydrogen-bonding interactions and resonance energy transfer.

ß-Cyclodextrin functionalized graphene as a highly conductive and multi-site platform for DNA immobilization and ultrasensitive sensing detection.

A versatile nanocomposite containing ß-cyclodextrin and graphene (CD-GR) was prepared through a simple chemical reduction method. The characterization experiments show that the nanocomposite remains the flake-like morphology of GR, but its solubility and stability in aqueous solution are greatly improved. Then the nanocomposite was modified at glassy carbon electrode (GCE) surface, and was used as a functional matrix for the covalent immobilization of probe DNA using 2,4,6-trichloro-1,3,5-triazine (TCT) as the crosslinker. Due to the synergetic effect of large surface area of GR and rich hydroxyl of CD, the probe density for the developed biosensor was determined to as high as 3.82×10(13) molecules cm(-2). Meanwhile, the biosensor shows high hybridization efficiency and hybridization kinetic. When the biosensor was applied for the impedance-based hybridization test, a wide linear range from 1.0×10(-16) to 1.0×10(-12) M and an ultralow detection limit of 3.4×10(-17) M were achieved. The biosensor also displays excellent stability, selectivity, and reproducibility.

Highly dispersible and stable copper terephthalate metal-organic framework-graphene oxide nanocomposite for an electrochemical sensing application.

A highly dispersible and stable nanocomposite of Cu(tpa)-GO (Cu(tpa) = copper terephthalate metal-organic framework, GO = graphene oxide) was prepared through a simple ultrasonication method. The morphology and structure of the obtained composite were characterized via scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis, Fourier-transform infrared (FT-IR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). On the basis of the characterization results, the binding mechanism of the Cu(tpa) and GO was speculated to be the cooperative interaction of π-π stacking, hydrogen bonding, and Cu-O coordination. The electrochemical sensing property of Cu(tpa)-GO composite was investigated through casting the composite on a glassy carbon electrode (GCE), followed by an electro-reduction treatment to transfer the GO in the composite to the highly conductive reduced form (electrochemically reduced graphene, EGR). The results demonstrated that the electrochemical signals and peak profiles of the two drugs of acetaminophen (ACOP) and dopamine (DA) were significantly improved by the modified material, owing to the synergistic effect from high conductivity of EGR and unique electron mediating action of Cu(tpa). Under the optimum conditions, the oxidation peak currents of ACOP and DA were linearly correlated to their concentrations in the ranges of 1-100 and 1-50 µM, respectively. The detection limits for ACOP and DA were estimated to be as low as 0.36 and 0.21 µM, respectively.

A novel highly selective colorimetric sensor for aluminum (III) ion using Schiff base derivative.

A novel colorimetric sensor, 2-hydroxy naphthaldehyde isonicotinoyl hydrazone (HINH), was easily synthesized by the condensation of isoniazid and 2-hydroxy-1-naphthaldehyde. The as-prepared compound showed effective colorimetric single selectivity and high sensitivity for aluminum cation in CH3CN/H2O (1:3) binary solutions. The detection limit is 1.0×10(-8) M Al(3+) based on UV-vis changes.

Efficient adsorption and photocatalytic degradation of Congo red onto hydrothermally synthesized NiS nanoparticles.

NiS nanoparticles (NiS NPs) have been hydrothermally prepared and characterized by the methods of X-ray diffraction, scanning electronic microscope, X-ray photoelectron spectroscopy, UV-Vis diffuse reflectance spectra, photoluminescence, and thermogravimetric analysis. NiS NPs exhibit fast adsorption in the removal of Congo red (CR) in aqueous solution, in which the pseudo-second-order model was the best to describe the adsorption kinetics, and the intraparticle diffusion was not only the rate-limiting step. The NiS NPs also exhibit efficient photocatalytic activity in the degradation of CR under visible-light irradiation, in which the 30 mg/L CR was almost completely degraded after illumination during 210 min. The •OH radicals in the process of photocatalytic degradation were observed by fluorescence technique.

Large scale synthesis of photoluminescent carbon nanodots and their application for bioimaging.

Carbon nanodots (CDs) have been synthesized at gram scale with a high yield (41.8%) by carbonization of sucrose with oil acid in one simple step. The synthesized CDs are monodisperse with a narrow size distribution (average 1.84 nm in size), and show a high fluorescence quantum yield (21.6%) without passivation. The PL intensity of the obtained CDs is pH independent over a range of 2-8. Besides, their PL intensity remains unchanged even after six hours of UV excitation and six months of storage, exhibiting excellent stability. The obtained CDs have been used for cell imaging. The results demonstrate that the prepared CDs have great potential for real applications.

Bis(triethano-lamine)nickel(II) sulfate.

The title compound, [Ni(C(6)H(15)NO(3))(2)]SO(4), contains two triethano-lamine (TEA) ligands bound to an Ni(2+) metal centre, which lies on a crystallographic inversion centre, and one sulfate anion located on a twofold rotation axis such that the asymmetric unit contains one-half molecule of the cation and of the anion. The triethano-lamine ligands coordinate via each axial N atom and two of the three O atoms, while the third arm of the ligand has the hydroxyl group pointing away from the metal centre. The sulfate anions are hydrogen bonded to the coordinated hydroxyl groups and also to the free arm, forming a two-dimensional supra-molecular hydrogen-bonded network expanding parallel to (010).

Diaqua-(triethano-lamine)copper(II) sulfate monohydrate.

The asymmetric unit of the title compound, [Cu(C(6)H(15)NO(3))(H(2)O)(2)]SO(4)·H(2)O, contains a complex cation, a sulfate anion and one uncoordinated water mol-ecule. In the complex cation, the Cu(II) ion is coordinated by five O atoms (three of which are from the triethano-lamine ligand and two from coordinated water mol-ecules) and one N atom of the triethano-lamine ligand in a typical Jahn-Teller-distorted octa-hedral geometry. Classical inter-molecular O-H⋯O hydrogen bonds link the cation, the sulfate anion and the water mol-ecule into a two-dimensional network.

(µ-4,4'-Bipyridine-κN:N')bis-[triaqua-(4,4'-bipyridine-κN)(3-nitro-phthalato-κO)cobalt(II)].

The title binuclear complex, [Co(2)(C(8)H(3)NO(6))(2)(C(10)H(8)N(2))(3)(H(2)O)(6)], has been synthesized hydro-thermally from 3-nitro-phthalic acid (H(2)NPA), Co(NO(3))(2)·6H(2)O and 4,4'-bipyridine (4,4'-bipy). The mol-ecule of the complex occupies a special position on an inversion centre. The Co(II) atom has a slightly distorted octa-hedral environment formed by two N atoms from two 4,4'-bipy ligands, one carboxyl-ate O atom from NPA, and three O atoms of water mol-ecules. An extensive O-H⋯O and N-H⋯O hydrogen-bonding system links mol-ecules of the complex into a three-dimensional network.

Chromatographic enantioseparations of binaphthyl compounds on an immobilized polysaccharide-based chiral stationary phase.

Seven binaphthyl compounds were enantioseparated by HPLC with an immobilized polysaccharide-based chiral stationary phase, Chiralpak IA. The experiments were performed under normal-phase conditions. Effects of polar modifier and column temperature on the retention time and separation factor were evaluated. All examined compounds obtained complete resolutions. This was the unique one ever reported that 1,1'-bi-2-naphthol and its monoether, diether and diester derivatives could all be enantioseparated on a given CSP. Apparent thermodynamic parameters were also deduced from Van't Hoff plots, and some aspects of chiral recognition mechanism were discussed further.

A novel three-dimensional coordination polymer constructed from pyrazine and copper(I): poly[[copper(I)-di-mu2-pyrazine-kappa4N:N'] 3,5-dicarboxybenzenesulfonate monohydrate].

In the title metal-organic framework complex, {[Cu(C(4)H(4)N(2))(2)](C(8)H(5)O(7)S).H(2)O}(n) or {[Cu(I)(pyz)(2)](H(2)SIP).H(2)O}(n) (pyz is pyrazine and H(3)SIP is 5-sulfoisophthalic acid or 3,5-dicarboxybenzenesulfonic acid), the asymmetric unit is composed of one copper(I) center, one whole pyrazine ligand, two half pyrazine ligands lying about inversion centres, one H(2)SIP(-) anion and one lattice water molecule, wherein each Cu(I) atom is in a slightly distorted tetrahedral coordination environment completed by four pyrazine N atoms, with the Cu-N bond lengths in the range 2.017 (3)-2.061 (3) A. The structure features a three-dimensional diamondoid network with one-dimensional channels occupied by H(2)SIP(-) anions and lattice water molecules. Interestingly, the guest-water hydrogen-bonded network is also a diamondoid network, which interpenetrates the metal-pyrazine network.