Stable Functional Groups Research Articles

A Spin-Labeled Derivative of Gossypol

Gossypol and its derivatives arouse interest due to their broad spectrum of biological activities. Despite its wide potential application, there is no reported example of gossypol derivatives bearing stable radical functional groups. The first gossypol nitroxide hybrid compound was prepared here via formation of a Schiff base. By this approach, synthesis of a gossypol nitroxide conjugate was performed by condensation of gossypol with a 4-amino-TEMPO (4-amino-2,2,6,6-tetramethylpiperidin-1-oxyl) free radical, which afforded the target product in high yield. Its structure was proven by a combination of NMR and EPR spectroscopy, infrared spectroscopy, mass spectrometry, and high-resolution mass spectrometry. In addition, the structure of the gossypol nitroxide was determined by single-crystal X-ray diffraction measurements. In crystals, the paramagnetic Schiff base exists in an enamine–enamine tautomeric form. The tautomer is strongly stabilized by the intra- and intermolecular hydrogen bonds promoted by the resonance of π-electrons in the aromatic system. NMR analyses of the gossypol derivative proved that in solutions, the enamine–enamine tautomeric form prevailed. The gossypol nitroxide at micromolar concentrations suppressed the growth of tumor cells; however, compared to gossypol, the cytotoxicity of the obtained conjugate was substantially lower.

Physical, mechanical and thermal properties of novel bamboo/kenaf fiber-reinforced polylactic acid (PLA) hybrid composites

This study investigates the physical, mechanical, and thermal properties of bamboo (BF) and kenaf (KF) fiber-reinforced polylactic acid (PLA) hybrid composites. Three hybrid (30BF-70KF, 50BF-50KF, and 70BF-30KF) and two non-hybrid (BF-PLA and KF-PLA) composites were developed through twin screw extrusion and compression molding techniques. The physical properties (density, void content, crystallinity via XRD, and chemical interactions via FTIR), mechanical properties (tensile, flexural, compressive, impact, and hardness), and thermal properties (Thermogravimetric analysis-TGA and Differential scanning calorimetry-DSC) were thoroughly analyzed. BF reinforcement reduced the composites’ density to 1.1826 g/cm³, while the inclusion of KF increased it to 1.2479 g/cm³. 50:50 blend of bamboo-kenaf reinforcement achieved the lowest void content of 0.27 %. The XRD patterns revealed heightened crystallinity in the BF-PLA composite. FTIR analysis showed stable functional groups, with O–H absorption bands indicative of cellulosic fibers. The BF-PLA non-hybrid composite exhibited the highest tensile strength at 25.95 MPa and compressive strength at 173.15 MPa, with the 30BF-70KF hybrid composite showing notable impact strength. Fractured morphology by FESEM revealed superior fiber-matrix adhesion for BF-PLA composite. TGA demonstrated a variation in thermal degradation temperatures, with the BF30-KF70 composite showing the highest onset of degradation at 484 °C. DSC analysis indicated a reduction in the glass transition temperature (Tg) across all fiber-reinforced samples and revealed significant adjustments in melting and crystallization temperatures. This research highlights the potential of BF-KF/PLA hybrid composites in the development of eco-friendly plastic furniture and consumer products.

Application value of ultrasonic contrast imaging and ultrasonic parameters in post-transplant renal surgery.

Utilize VUEBOX quantitative analysis software to perform quantitative analysis dynamic ultrasound contrast images of post-transplant renal patients were assessed quantitatively five parameters of ultrasonic contrast and two-dimensional ultrasound are examined to explore their six value in Diagnosing Renal Graft Dysfunction. A retrospective analysis was conducted on 73 post-transplant renal patients who underwent ultrasound contrast examinations at Yiyang Central Hospital from July 2022 to December 2023, They were diagnosed clinically and pathologically. Based on pathological and clinical diagnostic results, the patients were divided into three groups: 47 cases in the stable renal function group, 18 cases in the acute rejection (AR) group, and 8 cases in the delayed graft function (DGF) group. All patients underwent routine ultrasound and ultrasound contrast examinations post-transplantation. By comprehensively assessing renal function test results, clinical course, and pathological findings, differences in ultrasonic contrast quantitative parameters were analyzed. Additionally, ROC curves were constructed to evaluate the diagnostic efficacy of ultrasound contrast in discriminating between transplant renal rejection reactions and delayed renal function recovery. Statistically significant differences in characteristics, such as renal segmental artery resistance index, were observed among the stable renal function group, AR group, and DGF group (all P < 0.05), while peak systolic velocity showed no statistical significance (P > 0.05). Differences in cortical time to peak (TTP), medullary time to peak(TTP), main renal artery rise time (RT), main renal artery(TTP), and main renal artery fall time (FT) were statistically significant among the stable renal function group, AR group, and DGF group (P < 0.05). ROC curve analysis demonstrated that the accuracy of quantitative parameters for the DGF group and AR group was as follows: Renal artery TTP = Renal artery RT > Renal artery FT > Medulla TTP > Cortex TTP (with respective area under the curve values of 0.828, 0.828, 0.758, 0.742, 0.719). Among these, Renal artery TTP and Renal artery RT exhibited larger AUC values, with sensitivities of 87.5% each and specificities of 81.2 and 87.5%, respectively. There are discernible differences in VUEBOX quantitative parameters between post-transplant AR and DGF cases, thereby providing imaging references for diagnosing of acute rejection and functional impairment following renal transplantation.

Activation of NLRP3 inflammasome in patients with renal transplantation: relation to allograft dysfunction, inflammation, and renal fibrosis

ABSTRACT Background Chronic allograft dysfunction (CAD) represents a complex process of inflammatory response, fibrosis, and tissue restoration, mediated by a myriad of proinflammatory cytokines, enzymes, and growth factors. NOD-like receptor protein3 (NLRP3) inflammasome is one of the NLR protein families. It drives proteolysis of proinflammatory caspases which induces maturation of pro-interleukin (IL)-1β and pro-IL-18. The aim of this work is to study NLRP3 inflammasome activation in patients with renal transplantation in relation to allograft function, inflammation, and renal fibrosis. Methods Thirty renal transplant recipients (RTR): 15 patients with stable renal function (Group I), 15 patients with CAD (Group II), and 15 healthy subjects (Group III) were included. Serum and urinary NLRP3, caspase-1, and interleukin-1β were measured using an enzyme-linked immunosorbent assay (ELISA) kit. Serum high sensitivity C-reactive protein (hs-CRP) level was measured, and neutrophil-lymphocyte ratio (NLR) was calculated. Renal function was evaluated by serum creatinine (S.Cr) and estimated glomerular filtration rate (eGFR). Resistive index (RI) was calculated with Doppler ultrasonography. In patients with CAD, renal interstitial fibrosis (RIF) was graded in renal biopsies. Results Serum NLRP3, caspase-1, serum and urinary IL-1β, and hs-CRP showed a statistically significant increase in RTR, particularly in those with CAD compared to the controls with a positive correlation with each other, their urinary level, S. Cr, hs-CRP, NLR, RI, and RIF (p < 0.001). The receiver operating characteristic curve showed high diagnostic accuracy of serum NLRP3, caspase-1, and IL-1β in discriminating patients with CAD from patients with stable renal function. Conclusion The NLRP3-caspase1-IL-1β cascade is activated and upregulated in renal transplant recipients, particularly those with advanced renal impairment, and thus may play a role in developing CAD and renal fibrosis. They could be potential biomarkers for post-transplant outcome, follow-up, and early diagnosis. Moreover, their cascade could be a target for future anti-inflammatory therapeutic strategies for allograft dysfunction.

Exploring oxygen migration and capacitive mechanisms: Crafting oxygen-enriched activated carbon fiber from low softening point pitch

A green pitch fiber from coal tar distillation residue, with a softening point of 190 °C, was used to make activated carbon fiber through an in-situ oxygen-doped method. Oxygen-rich pitch-based activated carbon fibers (OPACFs) were successfully created with a three-stage stabilization process using this low softening point pitch fiber. The OPACFs exhibit a moderate pore size distribution and high surface oxygen content (20.83 at%). The migration and transformation of oxygen during this process were studied. Due to the formation of stable oxygen-containing functional groups (CO), the resulting material shows excellent electrochemical performance. It achieved a specific capacitance of 334 F/g at 0.5 A/g and maintained good rate capacity (73.7 %, 0.5–50 A/g) in a 6 M KOH electrolyte. The assembled supercapacitor displayed exceptional cycle stability, retaining 91.4 % capacitance at 1 A/g after 10,000 cycles. Further investigation revealed that the specific capacitance includes both surface-controlled and diffusion-controlled capacitance, with oxygen doping significantly enhancing the latter.

In situ synthesis of cross-linking gel polymer electrolyte for lithium metal batteries

The room temperature ionic conductivity of polyethylene oxide (PEO)-based polymer electrolytes is low, the electrochemical window is narrow, and the mechanical strength is relatively poor. In this work, a cross-linking gel-based solid composite polymer electrolyte (CG-SCPE) was synthesized by introducing electrochemically stable carbonate-based functional groups. The synthesized CG-SCPE presents excellent tensile strength (26 MPa) and a wide electrochemical stability window (> 4.5 V vs. Li/Li+). Meanwhile, the in situ polymerization method induced by thermal heating resulted in good compatibility between electrodes/electrolytes. In addition, the assembled LiNi0.5Co0.2Mn0.3O2/CG-SCPE/Li battery exhibited satisfactory electrochemical performance. Therefore, the gel polymer electrolyte CG-SCPE with cross-linking network provides the possibility for future application of safe and high-performance solid-state lithium metal batteries. The results indicate that the introduction of cross-linking framework can simultaneously improve the mechanical strength, thermal stability, and electrochemical performance of solid polymer electrolyte.

Chlorinated graphene and graphene nanoribbons: A density functional theory study

Functional groups based on halides, such as fluorine (F), chlorine (Cl), bromine (Br), and iodine (I), are crucial for understanding the chemical reactivity of graphitic nanomaterials. Except for I, halogens exhibit electronegativity greater than carbon (C); therefore, charge transfer from carbon to halogen is expected. First-principles density functional theory calculations were performed to determine the role of different Cl-functional groups (methyl-trichloride, ethyl-trichloride, chloride, acyl-chloride, vinyl-chloride, acetyl hypochlorite, chloramines, sulfonyl chloride, and more) on the electronic properties of graphene and graphene nanoribbons (GNRs). GNRs with zigzag edges (ZGNRs) and armchair edges (AGNRs) were studied. We analyzed the optimized structures, band structure, density of states, cohesive energy, and band gap. Our results revealed that the based-Cl functional groups can provide an alternative route to activate the borders and surfaces of sp2 carbon materials. Methyl-trichloride and acyl-chloride can induce magnetism and metallicity. Chloride and acyl-chloride are the most energetically stable functional groups attached to the edges. Surprisingly, methyl-trichloride or acyl-chloride functionalizing the surface of the AGNRs showed a direct (indirect) band gap for states with spin-up (spin-down). The results of aromatic (chlorobenzene- and dichlorobenzene-like structures) functionalization considering F, Cl, Br, and I are also shown. Finally, –F2 and –ClF functionalization cases are discussed.

Mechanisms for NOx emission control and ash deposition mitigation in sludge-coal blend combustion

This paper introduces the coupled treatment of alkali and alkaline earth metals (AAEMs)-rich coal with ferric sludge as a method to efficiently and economically control sludge NOx emissions and mitigate coal ash deposition through fuel interactions. We utilized a pilot-scale drop tube furnace to quantify NOx emissions and ash deposition, supported by spectral and energy dispersive analyses. The results demonstrated co-combustion controls NOx emissions by catalyzing the reaction between char and NO and the transformation into more stable N-containing functional groups. It also facilitates the formation of harmless N2 instead of NOx by enabling Ca/Fe-based minerals to react with protein and pyrrolic nitrogen. At 950 °C, blending 10% ferric sludge mitigated ash deposition, thanks to the capture and dilution effect of Si/Al/Fe-based minerals in ferric sludge. However, blending ferric sludge aggravated ash deposition of AAEMs-rich coal at 1250 °C, due to the formation of eutectics by Fe-based minerals and Ca/Na-based feldspars. Besides, the control of NOx was reduced at 1250 °C. Therefore, the co-combustion of AAEMs-rich coal with 10% ferric sludge at 950 °C exhibited excellent performance in both emission control and ash deposition mitigation. This study, grounded in the characteristics of minerals, provides a theoretical foundation for the efficient and economical in-situ control of NOx emissions and ash deposition. It advances the development of low-carbon, environmentally friendly technologies for coupled sludge and coal combustion.

Recent Progress in Sulfur-Containing High Refractive Index Polymers for Optical Applications.

The development in the field of high refractive index materials is a crucial factor for the advancement of optical devices with advanced features such as image sensors, optical data storage, antireflective coatings, light-emitting diodes, and nanoimprinting. Sulfur plays an important role in high refractive index applications owing to its high molar refraction compared to carbon. Sulfur exists in multiple oxidation states and can exhibit various stable functional groups. Over the last few decades, sulfur-containing polymers have attracted much attention owing to their wide array of applications governed by the functional group of sulfur present in the polymer repeat unit. The interplay of refractive index and various other polymer properties contributes to successfully implementing a specific polymer material in optical applications. The focus on developing optoelectronic devices induced an ever-increasing need to integrate different functional materials to achieve the devices' full potential. Several devices that see the potential use of sulfur in high refractive index materials are reviewed in the study. Like sulfur, selenium also exhibits high molar refraction and unique chemical properties, making it an essential field of study. This review covers the research and development in the field of sulfur and selenium in different forms of functionality, focusing on the chemistry of bonding and the optical properties of the polymers containing the heteroatoms mentioned above. The strategy and rationale behind incorporating heteroatoms in a polymer matrix to produce high-refractive-index materials are also described in the present review.

Pyrenecarboxaldehyde@Graphene Oxide Acted as a Highly Efficient ECL Emitter and Target-Triggered the Recyclable Cascade System as an Amplifier for Ultrasensitive APE1 Activity Detection.

Herein, pyrenecarboxaldehyde@graphene oxide (Pyc@GO) sheets with highly efficient electrochemiluminescence (ECL) as emitters were prepared by a noncovalent combination to develop a neoteric ECL biosensing platform for the ultrasensitive assessment of human apurinic/apyrimidinic endonuclease1 (APE1) activity. Impressively, the pyrenecarboxaldehyde (Pyc) molecules were able to form stable polar functional groups on the surface of GO sheets through the noncovalent π-π stacking mechanism to prevent intermolecular restacking and simultaneously generate Pyc@GO sheets. Compared with the tightly packed PAH nanocrystals, the Pyc@GO sheets significantly reduced internal filtering effects and diminished nonactivated emitters to enhance ECL intensity and achieve strong ECL emission. Furthermore, the APE1-activated initiators could trigger the recyclable cascade amplified system based on the synergistic cross-activation between catalytic hairpin assembly (CHA) and DNAzyme, which improved the signal amplification and transduction ability. Consequently, the developed ECL platform for the detection of APE1 activity displayed exceptional sensitivity with a low detection limit of 4.6 × 10-9 U·mL-1 ranging from 10-8 to 10-2 U·mL-1. Therefore, the proposed strategy holds great promise for the future development of sensitive and reliable biosensing platforms for the detection of various biomarkers.

High-efficiency recyclable reduced graphene oxide-tin oxide nanocomposite catalyst for esterification

Graphene oxide (GO) possesses 2D nanostructures and was synthesized indigenously via the enhanced Hummer method. It is well-accepted that the redox approach is a distinctive technique to fabricate GO on an expanded scale. Here, reduced graphene oxide-tin oxide (SnO2-rGO) nanocomposite material was produced for application as an efficient heterogeneous solid acid catalyst esterification reaction. Fourier transform infrared analysis was carried out to validate the incidence of oxygen functional groups in GO and SnO2-rGO nanocomposite. The Raman spectra of GO and SnO2-rGO nanocomposite have been simulated to get stable structure and functional groups. To get surface morphological and structural features, powder X-ray diffraction, scanning electron microscope-energy dispersive X-ray spectra, transmission electron microscope and high resolution-TEM analysis, and thermogravimetric analysis were delineated during this experimental study. It is seen that the catalyst has high efficiency for esterification reaction. The maximum efficiency (96% yield) was obtained when a 1:3 (acetic acid to benzyl alcohol) molar ratio, catalyst (25 mg), temperature (60 0C), and time (4 h) were maintained. The SnO2-rGO nanocomposite was recycled several times with a minimal loss of its efficiency.

Phosphorus-doped activated carbon as a platinum-based catalyst support for electrocatalytic hydrogen evolution reaction

Carbon is an excellent support that may influence the electronic structure of metal particles. However, carbon lacks functional groups on its surface, making it unsuitable for carrying catalysts, resulting in metal agglomeration. This can be solved by heteroatom doping to effectively optimize ligand structure and electronic characteristics of carbon materials, as well as enhance the intrinsic activity and steadiness of Pt/C catalysts. Herein, phosphorus-doped activated carbon (P-AC) was prepared as support for Pt catalysts to enhance the hydrogen evolution reaction (HER) under alkaline conditions. The main doped form of P-AC by potassium dihydrogen phosphate was identified as C3-PO, considered the most stable phosphorus-oxygen functional group in the carbon lattice with a key role in the HER process. The existence of C3-PO enhanced the interaction between P-AC and Pt nanoparticles, thereby tuning the electronic state of Pt and further optimising the adsorption of H* on Pt. Consequently, the resulting Pt/P-AC catalysts exhibited excellent HER activity (Tafel slope: 33.0 mV·dec−1, overpotential: 36.1 mV), with 4.6-fold incremented mass activity (1.220 A·mgpt−1) at a voltage of 70 mV than commercial catalysts containing 40 wt% Pt/C (0.266 A·mgpt−1). Moreover, a remarkable electrochemically active surface area (ECSA) of 66.95 m2·gPt−1 was observed in the Pt/P-AC catalysts. The Pt/P-AC catalysts also displayed high stability with better activity loss than commercial 40% Pt/C after 10,000 cycles. In sum, the proposed method looks promising for future syntheses of novel HER catalysts with high HER performance under alkaline conditions.

Development of High Durable Pore-Filling Anion Exchange Membranes for Water Electrolysis Application

Water electrolyzer is a device that converts renewable electrical energy into environmentally friendly chemical energy, hydrogen. Water electrolysis is mainly categorized into proton exchange membrane water electrolysis (PEMWE) and anion exchange membrane water electrolysis (AEMWE). Non-precious electrocatalysts and hydrocarbon-based polymeric membranes are used for two different systems. It is advantageous for AEMWE in terms of cost. However, low current density and chemical stability for current anion exchange membrane technology (AEM) restricts early market penetration. Thus, thedevelopment of low resistance and high durable AEMs is of importance. In this study, superior ion conductivity and high durable pore-filling AEMs were developed for AEMWE. Pore-filling AMEs with different contents of crosslinking monomers were prepared by the monomers using chemically stable anion exchangeable functional groups in a porous polyethylene(PE) substrate. Properties of the AEMs were characterized through areal resistance, ionic conductivity, ion exchange capacity, water uptake, swelling ratio, mechanical strength and hydrogen crossover. In addition, AEMWE performance and durability tests were also conducted. Acknowledgments This research was supported in part by Cooperative Research Program for Agriculture Science and Technology Development (Project No. PJ016253), Rural Development Administration, Republic of Korea and by 2021 Green Convergence Professional Manpower Training Program of the Korea Environmental Industry and Technology Institute funded by the Ministry of Environment.

Photoelectrochemical Asymmetric Catalysis Enables Enantioselective Heteroarylcyanation of Alkenes via C-H Functionalization.

The asymmetric difunctionalization of alkenes, a method transforming readily accessible alkenes into enantioenriched chiral structures of high value, has long been a focal point of organic synthesis. Despite tremendous efforts in this domain, it remains a considerable challenge to devise enantioselective oxidative dicarbofunctionalization of alkenes, even though these transformations can utilize stable and unfunctionalized functional group donors. In this context, we report herein a photoelectrocatalytic method for the enantioselective heteroarylcyanation of aryl alkenes, which employs unfunctionalized heteroarenes through C-H functionalization. The photoelectrochemical asymmetric catalysis (PEAC) method combines photoredox catalysis and asymmetric electrocatalysis to facilitate the formation of two C-C bonds operating via hydrogen (H2) evolution and obviating the need for external chemical oxidants.

Study on the Influence of Pre-Oxidation Treatment on Surface Wettability and Supercapacitive Performance of Coal-Based Activated Carbon

Coal possessing high fixed carbon content can be used for the preparation of activated carbon materials, including supercapacitance electrode carbon. Taixi anthracite has less ash content and high graphitization degree, which is a good candidate as a carbon source, while its low chemical activity affects the pore growth during the activated process. In this paper, using Taixi anthracite as the raw material, the effects of H2O2 pre-oxidation on the pore structure, surface chemical structure, and electrochemical properties of prepared activated carbon were studied. The results show that H2O2 successfully reduces the hydrophobic characteristics of the coal surface, which provides the possibility for the accessibility of the activator and the electrolyte. The activated carbon with H2O2 treatment at 15% concentration (AC-15%) shows high specific surface area (2016.50 m2/g), high specific capacitance (262 F/g), and high rate performance (63%), which is much higher than AC-0% without the pre-oxidation treatment. It is due to that the stable oxygen-containing functional groups (aldehyde and anthraquinone) on coal can improve the activity of activation carbon material and increase the wettability without affecting the electrical conductivity. In addition, the material shows high energy density and cyclic stability. This study provides an effective surface treatment approach for the preparation of a high-performance coal-based supercapacitance electrode material.

Study on the inhibition performance of double network physicochemical nanocomposite gel inhibitor on coal spontaneous combustion

To strengthen the inhibition effect of an inhibitor on spontaneous coal combustion throughout the process, this study used solution polymerization to synthesize hyaluronic acid and polyethylene glycol into a double network gel. The double network gel was grafted with a chemical inhibitor, epigallocatechin gallate, and polymerized with nanomaterial attapulgite to prepare a double network gel composite inhibitor with a whole-process inhibition effect. From the results of the scanning electron microscopy test, we found that the folds and pores on the surface of the inhibitor considerably increased with composite treatment. From the results of thermogravimetric analysis, it was proved that the average increase in each characteristic temperature point of the coal sample was 28.15%. According to the results of differential scanning calorimetry, it was found that the heat release interval of the inhibited sample was narrowed, and the total heat release was reduced by 2408.08 J/g. From the results of gas analysis, it was concluded that the production of CO, CO2, and CH4 by the inhibited sample markedly reduced, which verified the environmental friendliness of the inhibitor. Through a diffuse reflection infrared spectrum test, it was found that the inhibition treatment could deactivate the active groups in coal and increase the content of the ether bonds of the stable functional groups, which proved that the composite inhibitor is an excellent fire prevention material.

High Initial Coulombic Efficiency Hard Carbon Anodes Enabled by Facile Surface Annealing Engineering.

Hard carbon (HC) anode shows great potential due to its high capacity and excellent rate performance. However, state-of-the-art HC anode still suffers insufficient initial Coulomb efficiency (ICE) due to the abundant Li-trapping sites. Herein, we demonstrate a facile annealing engineering for HC anodes to improve the ICE and the mechanism is systematically studied. Accordingly, during the annealing process, metastable O- and N-containing functional groups are pyrolyzed, which cause the microstructure reconstruction of HC. Therefore, irreversible lithium ions adsorption is reduced significantly and the conversion of sp3 to sp2 C contributes to the localized graphitization of HC. Consequently, the optimized HC achieves ultra-high ICE of 90% from initial 61%. It is demonstrated that HC will adsorb H2 O and some organic species from environment gradually, causing conversion of some electrochemical stable functional groups to the irreversible Li-trapping sites. This work provides facile strategy and novel insight for high ICE HC anodes.

The Enhancing Effect of Stable Oxygen Functional Groups on Porous-Carbon-Supported Pt Catalysts for Alkaline Hydrogen Evolution.

The oxygen functionalization of carbon materials has widely been employed to improve the catalytic performance of carbon-supported Pt (Pt/C) catalysts. Hydrochloric acid (HCl) has often been employed to clean carbons during the preparation of carbon materials. However, the effect of oxygen functionalization through a HCl treatment of porous carbon (PC) supports on the performance of the alkaline hydrogen evolution reaction (HER) has rarely been investigated. Herein, the impact of HCl combined with the heat treatment of PC supports on the HER performance of Pt/C catalysts has been comprehensively investigated. The structural characterizations revealed similar structures of pristine and modified PC. Nevertheless, the HCl treatment resulted in abundant hydroxyl and carboxyl groups and the further heat treatment formed thermally stable carbonyl and ether groups. Among the catalysts, Pt loading on the HCl-treated PC followed by a heat treatment at 700 °C (Pt/PC-H-700) exhibited elevated HER activity with a lower overpotential of 50 mV at 10 mA cm-2 when compared to the unmodified Pt/PC (89 mV). Pt/PC-H-700 also exhibited better durability than the Pt/PC. Overall, novel insights into the impact of the surface chemistry properties of porous carbon supports on the HER performance of Pt/C catalysts were provided, which were useful for highlighting the feasible improvement of HER performances by regulating the surface oxygen species of porous carbon supports.

Variations in soil organic carbon storage and stability with vegetation restoration stages on the Loess Plateau of China

Soil organic carbon (SOC) plays the most significant role in climate change mitigation and ecosystem productivity. However, dynamic changes in the storage and stability of SOC during vegetation restoration and succession, especially the physical protection role of soil aggregates, are not well understood. This study, therefore, explored the variations in SOC storage and stability along with vegetation restoration by combining the physical protection of soil aggregates with the chemical structural stability of organic carbon (OC). OC fractions and carbon functional groups of bulk soil and soil aggregates were investigated using soil samples collected from abandoned farmland, grassland, miscellaneous shrubland, pioneer arbor forest, and coniferous forest plots representing typical vegetation restoration consequence on the Loess Plateau of China. Vegetation restoration enhanced clumps of clay particles with visible pores and cementing substances. The contents of OC fractions (total, inert, and active carbons) in bulk soil and aggregates significantly increased during vegetation restoration process. Total and active OC in macroaggregates (>0.25 mm) were significantly higher than those in other aggregate fractions, while inert OC had no significant difference among different aggregate fractions. The elevated absorption intensity, i.e., absolute content of OC functional groups, especially stable OC functional groups, enhanced SOC chemical stability during vegetation restoration. From the abandoned farmland to miscellaneous shrubland, the relative content of active OC functional groups significantly increased and was primarily distributed in macroaggregates (84.94–86.32%), while silt–clay aggregates (<0.053 mm) had higher relative content of stable functional groups (21.84–26.53%). A significant increase was observed in the relative content of the stable functional group from miscellaneous shrubland to pioneer arbor forest, primarily in silt–clay aggregates (∼27.15%). In the coniferous forest, stable functional groups mainly distributed in macroaggregates also showed the most pronounced increase (∼36.15%). We concluded that vegetation restoration improves the soil structure and storage and stability of SOC due to the increased accumulation of OC in macroaggregates and enhanced chemical stability of OC in silt–clay aggregates from the abandoned farmland to the pioneer arbor forest. However, SOC stability in the coniferous forest is significantly influenced by macroaggregates in the soil.

Effects of water immersion on the pore structure and thermodynamic properties of coal gangue

A large amount of coal gangue (CG) produced in coal mining accumulates to form CG hills, and the combustion properties change under the effect of leaching, increasing the risk of spontaneous combustion. The study was mainly carried out by nitrogen adsorption, infrared spectroscopy and thermogravimetry on the physicochemical properties of the CG under different immersion times (30, 60, 90 days). And the activation energy of the immersion CG at different oxidation or combustion states was calculated. The results show that the pyrite contained in gangue is oxidized after immersion, and the heat released by oxidation and the acid solution formed have an obvious effect on the pore expansion of gangue. The mesoporous and macroporous increase by 2.61% and 0.95% respectively, which strengthens the physical and chemical adsorption of oxygen for CG. The immersion process also destroys the structure of the gangue, transforming stable functional groups into active ones, especially the most significant increase in hydroxyl and oxygen-containing functional groups. The characteristic temperature changed under the action of water immersion, the cracking temperature increased, and other characteristic temperatures decreased, among which the ignition temperature decreased by about 20℃. In addition, the water immersion process inhibits the low-temperature oxidation stage of CG and promotes the high-temperature combustion stage, and the risk of spontaneous combustion is the strongest after 60 days of immersion in water. The results can provide guidance for the prevention of spontaneous combustion in drenched CG hills.