Reaction Of Precursor Research Articles

High formation of trichloroacetic acid from high molecular weight and ultra-hydrophilic components in freshwater raphidophytes upon chlorination

Raphidophytes are flagellate unicellular algae that causes algal blooms in drinking water sources. In Japan, it was recently reported that the concentration of trichloroacetic acid (TCAA), a major chlorinated disinfection byproduct (DBP), increased dramatically in drinking water when the source water contained raphidophytes. Additionally, raphidophytes produced haloacetic acid (HAA) precursors, especially TCAA precursors, in high concentrations. However, their properties are still unknown, and thus, well-designed countermeasures against DBP formation have not yet been established. Therefore, in this study, the HAA precursors originated from raphidophytes in natural water collected from the algal blooms in Muro Dam (Nara Prefecture, Japan) and Gonyostomum semen (G. semen), a raphidophyte species, cultivated in the laboratory, were characterized to provide the information for establishing suitable treatment strategies. Using several high-performance liquid chromatography columns, solid-phase extraction cartridges, and ultrafiltration devices, and the spectral profiles, we discovered that the HAA precursors are highly hydrophilic and high-molecular-weight compounds with acidic and phenolic functional groups. Further characterization of the high-molecular-weight fraction (> 3 kDa) from the G. semen culture showed that the HAA precursors had a molecular weight of ~10–60 kDa, and that they were not protein molecules despite containing a large amount of nitrogen atoms. Furthermore, the TCAAFP of the fraction (310 ± 25 μg/mg C) were as high as phenol, known as a reactive TCAA model precursor. The presence of unique and unreported DBP precursors was confirmed.

Room-Temperature One-Pot Synthesis of pH-Responsive Pyridine-Functionalized Carbon Surfaces.

Carbon surfaces (glassy carbon, graphite, and boron-doped diamond) were functionalized with layers composed of linked pyridinium and pyridine moieties using simple electrochemical reduction of trifluoroacetylpyridinium. The pyridinium species was generated in situ in solution by the reaction of trifluoroacetic anhydride and pyridine precursors and underwent electrochemical reduction at -1.97 V vs Fc/Fc+, as determined by cyclic voltammetry. The pyridine/pyridinium films were electrodeposited at room temperature, on a timescale of minutes, and were characterized using X-ray photoelectron spectroscopy. The as-prepared films have a net positive charge in aqueous solution at pH 9 and below due to the pyridinium content, confirmed by the electrochemical response of differently charged redox molecules at the functionalized surfaces. The positive charge can be enhanced further through protonation of the neutral pyridine component by controlling the solution pH. Moreover, the nitrogen-acetyl bond can be cleaved through base treatment to purposefully increase the neutral pyridine proportion of the film. This results in a surface that can be "switched" from functionally near neutral to a positive charge by treatment in basic and acidic solutions, respectively, through manipulation of the protonation state of the pyridine. The functionalization process demonstrated here is readily achievable at a fast timescale at room temperature and hence can allow for rapid screening of surface properties. Such functionalized surfaces present a means to test in isolation the specific catalytic performance of pyridinic groups toward key processes such as oxygen and CO2 reduction.

Copper-Catalyzed Direct Carbonylation of Carbenes toward the Synthesis of Propanedioic Acid Derivatives.

Carbenes are highly active reaction intermediates, which can be used as reaction precursors to modify organisms, drugs, and material molecules. In this work, we realized a new cheap metal-catalyzed carbonylation of carbene to give propanedioic acid derivatives. With copper salt as the catalyst, synthetically important malonates and related compounds were produced in good yields under mild reaction conditions.

Turning Waste into Treasure: Multicolor Carbon Dots Synthesized from Waste Leather Scrap and their Application in Anti-Counterfeiting

Using biomass materials to prepare carbon dots (CDs) has received significant interest. As a cheap and environmentally friendly material, waste leather scrap can be used for the preparation of CDs and performance tuning. Herein, waste leather scrap is used as a precursor reactant to fabricate multicolor (red, green, and blue) carbon dots (R-CDs, G-CDs, and B-CDs) with a tunable emission wavelength via a simple one-step hydrothermal/solvothermal strategy using only a nitrogen source (p-phenylenediamine or o-phenylenediamine) for doping. The morphology, structure, and optical properties of the CDs were investigated by transmission electron microscopy (TEM), Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), Raman spectroscopy, ζ-potential measurements, X-ray photoelectron spectroscopy (XPS), ultraviolet–visible (UV–vis), spectroscopy, photoluminescence (PL), and UV-differential reflectance spectroscopy (UV-DRS). Results showed that the sizes of R-CDs, G-CDs, and B-CDs are 10.0, 7.4, and 2.5 nm, respectively, and all have a typical crystal plane of graphitic carbon structure rich in chemical groups such as C═O, −OH, C–N, etc. The detailed characterization and comparison of the three types of CDs confirm that the size and functional groups can effectively add other energy levels for electron transitions and tuning of luminescent properties of CDs. The emission wavelengths of R-CDs, G-CDs, and B-CDs are 612, 535, and 429 nm, and at the same time, the energy levels were calculated by UV–vis DRS to be 2.11, 2.43, and 2.58 eV, respectively. Because of the stable optical properties and excellent chemical performance, CDs can be employed as ink and flexible films. The utilization of renewable waste leather scrap, along with convenient hydrothermal/solvothermal methods, paves the way to the sustainable, cost-effective synthesis of CDs for practical applications in anti-counterfeiting.

Construction of high–loading 3D Co[sbnd]N[sbnd]C catalyst for oxygen reduction reaction in Zn–air batteries

The development of single atom catalysts is considered as a hotspot in the field of electrocatalysis. As the representative of single atom catalysts, metal and nitrogen co–doped carbon (MNC) attracts worldwide attentions due to its great potential in the application of oxygen reduction reaction (ORR). However, the actual preparation of MNC still confronts with tedious procedure, harsh condition and relatively low loading of single metal atom. In this work, we successfully prepare high–loading 3D CoNC architecture by a facile oxidation polymerization followed by pyrolysis process employing 3D nitrogen–doped graphene hydrogel (NGH) and pyrrole (PY) as the reaction precursors. Benefitting from the individual advantages of 3D NGH and PY, the resultant 3D CoNC possesses unique 3D architecture, high–loading single Co atom (2.74 wt%), large specific surface area and enriched mesopores, which benefit the exposure of sufficient catalytic sites and facilitate electrons transfer and ions transport, thus generating much enhanced ORR performance. When used as the cathode catalyst for zinc–air batteries (ZABs), it shows comparable performance with commercial Pt/C catalyst. Clearly, our finding offers a good guidance on the design and synthesis of advanced high–loading single atom catalysts.

Photoinduced Dithiolane Crosslinking for Multiresponsive Dynamic Hydrogels.

While many hydrogels are elastic networks crosslinked by covalent bonds, viscoelastic hydrogels with adaptable crosslinks are increasingly being developed to better recapitulate time and position-dependent processes found in many tissues. In this work, 1,2-dithiolanes are presented as dynamic covalent photocrosslinkers of hydrogels, resulting in disulfide bonds throughout the hydrogel that respond to multiple stimuli. Using lipoic acid as a model dithiolane, disulfide crosslinks are formed under physiological conditions, enabling cell encapsulation via an initiator-free light-induced dithiolane ring-opening photopolymerization. The resulting hydrogels allow for multiple photoinduced dynamic responses including stress relaxation, stiffening, softening, and network functionalization using a single chemistry, which can be supplemented by permanent reaction with alkenes to further control network properties and connectivity using irreversible thioether crosslinks. Moreover, complementary photochemical approaches are used to achieve rapid and complete sample degradation via radical scission and post-gelation network stiffening when irradiated in the presence of reactive gel precursor. The results herein demonstrate the versatility of this material chemistry to study and direct 2D and 3D cell-material interactions. This work highlights dithiolane-based hydrogel photocrosslinking as a robust method for generating adaptable hydrogels with a range of biologically relevant mechanical and chemical properties that are varied on demand.

Preliminary Reactivity Test for Precursors of Alkali-Activated Materials

Alkali-activated materials (AAMs) result from the dissolution process and polycondensation of precursors in high pH solutions. This material is considered alternative cement with similar properties and lower environmental impact than Portland cement. However, AAMs are subjected to the same standardization applied to cement-based materials since no formal methods exist to characterize this material and/or the precursor reactivity. Therefore, this work aims to develop a method to characterize the reactivity of the main precursors used to produce AAMs. Hence, the precursors were assessed in two steps after chemical, physical, and mineralogical characterization. The first step evaluated the crystallinity change of the material after the acid attack by mixing 1 g of each material in 100 mL of 1% HF solution for 6 h at ambient temperature. The crystallinity change was evaluated by comparing the X-ray diffraction of the materials before and after the acid attack. The second step involved evaluating the formation of geopolymerization products in the pastes of studied precursors through FTIR test. The pastes were produced with Na2SiO3 and NaOH as activators. After 28 days of curing, the pastes were submitted to a FTIR test for structural analysis. This method was tested evaluating the reactivity of traditional precursors for alkali activation (i.e., silica fume (SF), blast furnace slag (BFS), and metakaolin (MK)), in addition sugarcane bagasse ash mechanically treated (SCBAM) and sugarcane bagasse ash mechanically and heat treated (SCBAMH) since SCBA is a promising precursor for alkali activation. Considering the crystallinity change of precursors (step 01), the formation of geopolymerization products (step 02), and the chemical composition of precursors (preliminary characterization), it could be concluded that: (i) surface area is not relevant to materials with small particle size (<23 µm); (ii) amorphous area is only relevant if the material exhibits the optimal chemical composition; and (iii) the chemical composition is a crucial parameter for alkali activation. In addition, the potential precursors for alkali activation should have a significant amorphous halo and a SiO2/Al2O3 ratio of 2 to 5. Also, it could be concluded that SF and SCBAMH do not exhibit adequate reactivity while BFS, MK, and SCBAM can be classified as reactive precursors.

Effects of deposition temperature on the wear behavior and material properties of plasma enhanced atomic layer deposition (PEALD) titanium vanadium nitride thin films

This work investigates the effects of deposition temperature on the wear behavior and material properties of recently developed plasma enhanced atomic layer deposited (PEALD) TiVN films. ∼50–100 nm thick TixV1-xN (x ~ 0.5, hereto referred to as TiVN) films were deposited using PEALD on Si substrates with thermal oxide at a range of deposition temperatures (150 °C, 200 °C, 250 °C, 300 °C, 350 °C). Wear testing was performed on each film using a linearly reciprocating tribometer in a controlled humidity environment. Wear rates of the TiVN films varied with deposition temperature, with the 250 °C sample achieving ultralow wear(5.4 × 10−7 mm3/Nm), while the 150 °C sample wore through the film completely in early sliding cycles. Along with their low wear properties, these PEALD TiVN films were found to have low electrical resistivity when deposited above 150 °C. Film density and crystallite size increased with increasing deposition temperature up to 250 °C, where these properties plateaued. High compressive residual stresses were measured, ranging from 2.7 to 7.7 GPa. XRD Bragg peak intensities showed that films with increasing deposition temperatures had higher degrees of crystallinity. XPS indicated that above 150 °C deposition temperatures, impurities in the film were reduced by ∼4x. Higher deposition temperatures allow for increased adatom mobility, which can lead to higher densities and crystallinity, which are typically associated with lower wear rates. At deposition temperatures below 200 °C, precursor reactivity is sluggish and there is insufficient energy for complete surface reactions to occur, leading to film contamination and less dense films. The subtle differences in wear rates above 200 °C deposition temperature indicated that there are competing material properties that can either contribute to or detract from the wear behavior of the film, and a combination of desirable mechanical, physical, structural, and chemical properties are required for ultra-low wear rates to be achieved. The low wear and friction properties and low electrical resistivity of these films combined with the low deposition temperature, conformality, and atomic layer thickness control of PEALD make them potential candidates for applications such as thermally sensitive microelectronics and MEMS/NEMS.

New Aminobiphenylcysteine Derivatives in Globin and Urine of Rats Dosed with 4-Aminobiphenyl, a Tobacco Smoke Carcinogen.

The 4-biphenylnitrenium ion (BPN), a reactive metabolic intermediate of the tobacco smoke carcinogen 4-aminobiphenyl (4-ABP), can react with nucleophilic sulfanyl groups in glutathione (GSH) as well as in proteins. The main site of attack of these S-nucleophiles was predicted using simple orientational rules of aromatic nucleophilic substitution. Thereafter, a series of presumptive 4-ABP metabolites and adducts with cysteine were synthesized, namely, S-(4-amino-3-biphenyl)cysteine (ABPC), N-acetyl-S-(4-amino-3-biphenyl)cysteine (4-amino-3-biphenylmercapturic acid, ABPMA), S-(4-acetamido-3-biphenyl)cysteine (AcABPC), and N-acetyl-S-(4-acetamido-3-biphenyl)cysteine (4-acetamido-3-biphenylmercapturic acid, AcABPMA). Then, globin and urine of rats dosed with a single ip dose of 4-ABP (27 mg/kg b.w.) was analyzed by HPLC-ESI-MS2. ABPC was identified in acid-hydrolyzed globin at levels of 3.52 ± 0.50, 2.74 ± 0.51, and 1.25 ± 0.12 nmol/g globin (mean ± S.D.; n = 6) on days 1, 3, and 8 after dosing, respectively. In the urine collected on day 1 (0-24 h) after dosing, excretion of ABPMA, AcABPMA, and AcABPC amounted to 1.97 ± 0.88, 3.09 ± 0.75, and 3.69 ± 1.49 nmol/kg b.w. (mean ± S.D.; n = 6), respectively. On day 2, excretion of the metabolites decreased by one order of magnitude followed by a slower decrease on day 8. Regarding the possible formation of AcABPC from ABPC, N-acetylation of the amino group at the biphenyl moiety prior to that at cysteine appears to be very unlikely. Thus, the structure of AcABPC indicates the involvement of N-acetyl-4-biphenylnitrenium ion (AcBPN) and/or its reactive ester precursors in in vivo reactions with GSH and protein-bound cysteine. ABPC in globin might become an alternative biomarker of the dose of toxicologically relevant metabolic intermediates of 4-ABP.

Tailored deep-eutectic solvent method to enable 3D porous iron fluoride bricks for conversion-type lithium batteries

A Fe-based deep eutectic solvent is proposed as both the reaction medium and precursor to synthesize O-doped FeF 3 porous bricks as conversion cathode with high reversible capacity. Conversion-type fluoride cathode can provide considerable energy density for Li batteries, however its scalable and facile synthesis strategies are still lacking. Here, a novel Fe-based deep eutectic solvent composed of nitrite and methylsulfonylmethane is proposed as both the reaction medium and precursor to synthesize O-doped FeF 3 porous bricks. This method is cheaper, safe, mildly operable, environmentally friendly and recyclable for non-fluorinated metal cations. The homogenization of charge and mass transport in cathode network effectively mitigates the volume extrusion and electrode coarsening even for the micro-sized monolithic particles. The Co-solvation modulated fluoride cathode delivers high reversible capacity in a wide temperature range (486 and 235 mA h g −1 at 25 °C and −20 °C respectively), excellent rate performance (312 mA h g −1 at 1000 mA g −1 ), corresponding to an energy density as high as 672.1 W h kg −1 under a power density of 2154.3 W kg −1 . The successful operation of fluoride pouch-cell with a capacity exceeding 450 mA h g −1 (even under thin Li foil and lean electrolyte conditions) indicates its potentiality of commercial application.

Real-space imaging of a phenyl group migration reaction on metal surfaces

The explorations to extend present chemical synthetic methods are of great importance to simplify synthetic routes of chemical species. Additionally, understanding the chemical reaction mechanisms is critical to achieve controllable synthesis for applications. Here, we report the on-surface visualization and identification of a phenyl group migration reaction of 1,4-dimethyl-2,3,5,6-tetraphenyl benzene (DMTPB) precursor on Au(111), Cu(111) and Ag(110) substrates. With the combination of bond-resolved scanning tunneling microscopy (BR-STM), noncontact atomic force microscopy (nc-AFM) and density functional theory (DFT) calculations, the phenyl group migration reaction of DMTPB precursor is observed, forming various polycyclic aromatic hydrocarbons on the substrates. DFT calculations reveal that the multiple-step migrations are facilitated by the hydrogen radical attack, inducing cleavage of phenyl groups and subsequent rearomatization of the intermediates. This study provides insights into complex surface reaction mechanisms at the single molecule level, which may guide the design of chemical species.

Preparation of Cu2O/Au Composite Nanomaterials for Effective Reduction of 4‐Nitrophenol

AbstractThe conversion of nitroaromatics to aminobenzene plays an important role in the synthesis of medicines or fine chemicals. In this work, we successfully prepared Cu2O/Au nanocubes with different Au content for the reduction of 4‐nitrophenol. With the increase of gold precursor concentration or reaction time, the density of Au nanoparticles (NPs)on Cu2O surface increases, which results in the stronger electron transfer between Au and Cu2O, and thus the better synergistic catalytic performance of Cu2O/Au nanoparticles toward 4‐Nitrophenol (4‐NP). In this work, we found the Au component in the nanoparticles played an important role in charge redistribution and transfer, as well as the adsorption and reduction of 4‐NP. Therefore, the degradation performance of Cu2O/Au composite is better than that of pure Cu2O, and the degradation rate of 4‐NP can reach almost 90 % in 10 min, therefore providing a new idea for the rational design of effective nanocatalysts.

Orange-Emissive Carbon Dots with High Photostability for Mitochondrial Dynamics Tracking in Living Cells.

Mitochondria play significant roles in maintaining a stable internal environment for cell metabolism. Hence, real-time monitoring of the dynamics of mitochondria is essential for further understanding mitochondria-related diseases. Fluorescent probes provide powerful tools for visualizing dynamic processes. However, most mitochondria-targeted probes are derived from organic molecules with poor photostability, making long-term dynamic monitoring challenging. Herein, we design a novel mitochondria-targeted probe based on carbon dots with high performance for long-term tracking. Considering that the targeting ability of CDs is related to surface functional groups, which are generally determined by the reaction precursors, we successfully constructed mitochondria-targeted O-CDs with emission at 565 nm through solvothermal treatment of m-diethylaminophenol. The O-CDs are bright with a high quantum yield of 12.61%, high mitochondria-targeting ability, and good stability. The O-CDs possess a high quantum yield (12.61%), specific mitochondria-targeting ability, and outstanding optical stability. Owing to the abundant hydroxyl and ammonium cations on the surface, O-CDs showed obvious accumulation in mitochondria with a high colocalization coefficient of up to 0.90 and remained steady even after fixation. Besides, O-CDs showed outstanding compatibility and photostability under various interruptions or long-time irradiation. Therefore, O-CDs are preferable for the long-term tracking of dynamic mitochondrial behavior in live cells. We first observed the mitochondrial fission and fusion behaviors in HeLa cells, and then, the size, morphology, and distribution of mitochondria in physiological or pathological conditions were clearly recorded. More importantly, we observed different dynamics interactions between mitochondria and lipid droplets during the apoptosis and mitophagy processes. This study provides a potential tool for exploring interactions between mitochondria and other organelles, further promoting the research on mitochondria-related diseases.

Unraveling the neglected role of elemental sulfur in chromate removal by sulfidated microscale zero-valent iron

Elemental sulfur (S0), as an oxidation product of low-valent sulfur, is widely believed to inhibit the reactivity of sulfidated zero-valent iron (S-ZVI). However, this study found that the Cr(VI) removal and recyclability of S-ZVI with S0 as the dominant sulfur species were superior to those FeS or iron polysulfides (FeSx, x > 1) dominated ones. The more S0 directly mixed with ZVI, the better Cr(VI) removal obtained. This was ascribed to the formation of micro-galvanic cells, the semiconductor properties of cyclo-octasulfur S0 with sulfur atom substituted by Fe2+, and the in situ generations of highly reactive iron monosulfide (FeSaq) or polysulfides precursors (FeSx,aq). The Cr(VI) sequestration of FeSx,aq was 1.2–2 times that of FeSaq, and the reaction rate of amorphous iron sulfides (FexSy) in the removal of Cr(VI) by S-ZVI was 8- and 66-fold faster than that of crystalline FexSy and micron ZVI, respectively. The interaction of S0 with ZVI required direct contact and needed to overcome the spatial barrier caused by FexSy formation. These findings reveal the role of S0 in Cr(VI) removal by S-ZVI and guide the future development of in situ sulfidation technologies to utilize the highly reactive FexSy precursors for field remediation.

Activated cascade effect for dual-mode ratiometric and smartphone-assisted visual detection of curcumin and F− based on nitrogen-doped carbon dots

The growing persistence of harmful ion or drug molecular residues has always been considered as a matter of concern due to its importance in biological and environmental processes, which requires taking measures to maintain environmental health sustainably and effectively. Inspired by the multi-system and visual quantitative detection of nitrogen-doped carbon dots (N-CDs), we develop a novel cascade nano-system based on dual emission carbon dots for on-site visual quantitative detection of curcumin and fluoride ion (F−). Herein, tris (hydroxymethyl) aminomethane (Tris) and m-dihydroxybenzene (m-DHB) are elected as reaction precursors to synthesize dual-emission N-CDs by a one-step hydrothermal method. The obtained N-CDs exhibit dual emission peaks at 426 nm (blue) and 528 nm (green) with quantum yields of 53 % and 71 %, respectively. Then, trace curcumin and F− intelligent off-on-off sensing probe is formed by taking advantage of the activated cascade effect. As for the occurrence of inner filter effect (IFE) and fluorescence resonance energy transfer (FRET), the green fluorescence of N-CDs quenches remarkably, called as OFF initial state. Then the curcumin-F− complex leads to the hypochromatic shift of the absorption band from 532 to 430 nm, which activates the green fluorescence of N-CDs, named as ON state. Meanwhile, the blue fluorescence of N-CDs is quenched due to the FRET, called as OFF terminal state. This system shows good linear relationships from 0 to 35 μM and 0 to 40 μM with low detection limits of 29 nM and 42 nM for curcumin and F− ratiometric detection, respectively. Moreover, a smartphone-assisted analyzer is developed for on-site quantitative detection. Furthermore, we design a logic gate for logistics information storage, which proves the possibility of a logic gate based on N-CDs in practical application. Thus, our work will provide an effective strategy for environmental quantitative monitoring and information storage encryption.

Selective removal of copper (II) ions from aqueous solution using pyridyl-bridged mesoporous organosilica hybrid adsorbent

The incorporation of active functional groups into the mesoporous organosilica hybrid materials is efficient for various applications. A newly designed mesoporous organosilica adsorbent was prepared using diaminopyridyl groups bridged-(bis-trimethoxy)organosilane (DAPy) precursor by using Pluronic P123 as structure directing template via sol-gel co-condensation method. The hydrolysis reaction of DAPy precursor and tetraethyl orthosilacate (TEOS) with a DAPy content of about 20 mol% to TEOS were incorporated into the mesopore walls of the mesoporous organosilica hybrid nanoparticles (DAPy@MSA NPs). Low-angle XRD and FT-IR, N2 adsorption-desorption analysis, SEM, TEM, and TG analysis were used to characterize the synthesized DAPy@MSA NPs. The DAPy@MSA NPs exhibit an order mesoporous structure with a high surface area, mesopore size and pore volume of approximately ∼465 m2/g, 4.4 nm and 0.48 cm3/g, respectively. The pyridyl groups integrated DAPy@MSA NPs showed the selective adsorption of Cu2+ ions from the aqueous medium by metal-ligand complex coordination of Cu2+ ions with the integrated pyridyl groups and the pendant hydroxyl (-OH) functional groups present into the mesopore walls of the DAPy@MSA NPs. In the presence of other competitive metal ions (Cr2+, Cd2+, Ni2+, Zn2+, and Fe2+), the DAPy@MSA NPs showed relatively high adsorption of Cu2+ ions (276 mg/g) from aqueous solution as compared to the other competitive metal ions at the same concentration (100 mg/L) of initial metal ion solution.

Synchronous biostimulants recovery and dewaterability enhancement of anaerobic digestion sludge through post-hydrothermal treatment

In this study, we investigated the effects of hydrothermal temperature on molecular reaction pathways and the plant growth of dissolved organic matters (DOMs) in anaerobic digestion sludge (ADS) via post-hydrothermal treatment (PHT). ADS-derived DOMs mainly comprise lignins/carboxyl-rich alicyclic molecules-like and proteins/aliphatic-like compounds featured with enriched N1-2O6-7 and O8-10 fragments. With the increase in the hydrothermal (HT) temperature, the relative abundance of the compounds with < 7O atoms in DOMs gradually increased in HT-treated samples. Furthermore, based on Fourier transforms ion cyclotron resonance mass spectrometry (FT-ICR-MS)-based reactomics, we found that CHON compounds possessed the highest reactivity, and that reaction of carbonyl (loss of glyoxal (−C2H2O2)) with unique reaction precursors possessed the largest number of high-frequency reactions at different HT temperatures. Consequently, DOM160 contained higher levels of N&O heterocyclic compounds and acetic acid, inhibiting pakchoi growth, and causing an increase in superoxide dismutase activity in the roots. However, DOM200 comprised a higher content of amino acids and humic/fulvic acids, increasing indole-3-acetic acid concentration and H+-ATPase activity in the pakchoi roots, thus exhibiting higher plant activity. Overall, the best HT temperature for ADS dewaterability and the recovery of organic matter was found to be 200 °C. These findings proposed a promising approach for synchronously recycling biostimulants, deep dewatering of ADS via PHT, and further improving the carbon–neutral operation of wastewater treatment plants.

Synthesis and Characterizations of Novel Isatin-s-Triazine Hydrazone Derivatives; X-ray Structure, Hirshfeld Analysis and DFT Calculations

A novel series of isatin-s-triazine hydrazone derivatives has been synthesized and reported herein. The synthetic methodology involved the reaction of s-triazine hydrazine precursors with isatin derivatives in the presence of CH3COOH as a catalyst and EtOH as solvent to afford the corresponding target products 6a-e in high yields and purities. The characterization data obtained from elemental analysis, FT-IR, NMR (1H- and 13C-) were in full agreement with the expected structures. Furthermore, an X-ray single crystal diffraction study of one of the target s-triazine hydrazone derivatives, 6c confirmed the structure of the desired compounds. It crystallized in the triclinic crystal system and P-1 space group with a = 10.3368(6) Å, b = 11.9804(8) Å, c = 12.7250(5) Å, α = 100.904(4)°, β = 107.959(4)° and γ = 109.638(6)°. The different non-covalent interactions which contributed in the molecular packing of 6c were analyzed using Hirshfeld analysis. The molecular packing of the organic part of the crystal structure showed important O…H (7.1%), C…H (16.4%), C…C (1.6%), H…H (34.8%), N…H (8.0%) and C…N (4.0%) interactions while for the crystal solvent, the O…H (21.3%), H…H (61.2%) and N…H (8.1%) contacts are the most significant. The studied compound 6c is polar and has a net dipole moment of 5.6072 Debye based on DFT study.

Rationally Designed Manganese-Based Metal-Organic Frameworks as Altruistic Metal Oxide Precursors for Noble Metal-Free Oxygen Reduction Reaction.

The sluggish oxygen reduction reaction (ORR) at the cathode is challenging and hinders the growth of hydrogen fuel cells. Concerning kinetic values, platinum is the best known catalyst for ORR; however, its less abundance, high cost, and corrosive nature warrant the development of low-cost catalysts. We report the hydrothermal synthesis of two novel Mn-based metal-organic frameworks (MOFs), [Mn2(DOT)(H2O)2]n (Mn-SKU-1) and [Mn2(DOT)2(BPY)2(THF)]n (Mn-SKU-2) (DOT = 2,5-dihydroxyterephthalate; BPY = 4,4'-bipyridine). Mn-SKU-1 contains dimeric Mn(II) centers where the two corner-shared MnO6 octahedra fuse to give rise to an infinite Mn2O10 cluster, whereas the two Mn(II) ions coordinate to DOT and BPY moieties to give rise to a pillared structure in Mn-SKU-2 and form a 3D → 3D homo-interpenetration MOF with a twofold interpenetrated net. The pyrolysis of as-synthesized Mn-MOFs at 600 °C under N2 produced exclusively porous α-Mn2O3 composites (PSKU-1 and PSKU-2), with the BET surface area of 90.8 (for PSKU-1) and 179.3 m2 g-1 (for PSKU-2). These mesoporous MOF-derived α-Mn2O3 composites were modified as cathode materials for the electrocatalytic reduction of oxygen. The onset potential for the oxygen reduction reaction was found to be 0.90 V for PSKU-1 and 0.93 V for PSKU-2 versus RHE in 0.1 M KOH solution, with the current density of 4.8 and 6.0 mA cm-2, respectively, at 1600 rpm. Based on the RDE/RRDE results, the electrocatalytic oxygen reduction occurs majorly via the four-electron process. The electrocatalyst PSKU-2 is cheap, easy to use, retains 90% of its activity after 10 h of continuous use, and offers higher recyclability than Pt/C. The onset potential maximum current density and kinetic values (Jk = 11.68 mA cm-2 and Tafel slope = 85.0 mV dec-1) obtained in this work are higher than the values reported for pure Mn2O3.

Highly efficient construction of sustainable bacterial cellulose aerogels with boosting PM filter efficiency by tuning functional group

Air pollution has become a major public health concern, attracting considerable attention from researchers working on environmentally friendly and sustainable materials. In this work, bacterial cellulose (BC) derived aerogels were fabricated by the directional ice-templated method and used as filters to remove PM particles. We modified the surface functional groups of BC aerogel with reactive silane precursors, and investigated the interfacial and structural properties of those aerogels. The results show that BC-derived aerogels have excellent compressive elasticity, and their directional growth orientation inside the structure significantly reduced pressure drop. Moreover, the BC-derived filters exhibit an exceptional quantitative removal effect on fine particulate matter, which, in the presence of high concentrations of fine particulate matter, they can achieve a high-efficiency removal standard of 95 %. Meanwhile, the BC-derived aerogels showed superior biodegradation performance in the soil burial test. These results paved the way for BC-derived aerogels development as a great sustainable alternative to treat air pollution.