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1.
Proc Natl Acad Sci U S A ; 120(25): e2220007120, 2023 06 20.
Artigo em Inglês | MEDLINE | ID: mdl-37307485

RESUMO

What constitutes a habitable planet is a frontier to be explored and requires pushing the boundaries of our terracentric viewpoint for what we deem to be a habitable environment. Despite Venus' 700 K surface temperature being too hot for any plausible solvent and most organic covalent chemistry, Venus' cloud-filled atmosphere layers at 48 to 60 km above the surface hold the main requirements for life: suitable temperatures for covalent bonds; an energy source (sunlight); and a liquid solvent. Yet, the Venus clouds are widely thought to be incapable of supporting life because the droplets are composed of concentrated liquid sulfuric acid-an aggressive solvent that is assumed to rapidly destroy most biochemicals of life on Earth. Recent work, however, demonstrates that a rich organic chemistry can evolve from simple precursor molecules seeded into concentrated sulfuric acid, a result that is corroborated by domain knowledge in industry that such chemistry leads to complex molecules, including aromatics. We aim to expand the set of molecules known to be stable in concentrated sulfuric acid. Here, we show that nucleic acid bases adenine, cytosine, guanine, thymine, and uracil, as well as 2,6-diaminopurine and the "core" nucleic acid bases purine and pyrimidine, are stable in sulfuric acid in the Venus cloud temperature and sulfuric acid concentration range, using UV spectroscopy and combinations of 1D and 2D 1H 13C 15N NMR spectroscopy. The stability of nucleic acid bases in concentrated sulfuric acid advances the idea that chemistry to support life may exist in the Venus cloud particle environment.


Assuntos
Bivalves , Vênus , Adenina , Agressão , Ácidos Sulfúricos
2.
Small ; 20(16): e2308677, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38009515

RESUMO

Fuel cells offer great promise for portable electricity generation, but their use is currently limited by their low durability, excessive operating temperatures, and expensive precious metal electrodes. It is therefore essential to develop fuel cell systems that can perform effectively using more robust electrolyte materials, at reasonable temperatures, with lower-cost electrodes. Recently, proton exchange membrane fuel cells have attracted attention due to their generally favorable chemical stability and quick start-up times. However, in most membrane materials, water is required for proton conduction, severely limiting operational temperatures. Here, for the first time it is demonstrated that when acidified, PAF-1 can conduct protons at high temperatures, via a unique framework diffusion mechanism. It shows that this acidified PAF-1 material can be pressed into pellets with high proton conduction properties even at high temperatures and pellet thickness, highlighting the processibility, and ease of use of this material. Furthermore, a fuel cell is shown with high power density output is possible using a non-precious metal copper electrode. Acid-doped PAF-1 therefore represents a significant step forward in the potential for a broad-purpose fuel cell due to it being cheap, robust, efficient, and easily processible.

3.
Glob Chang Biol ; 30(3): e17213, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38436125

RESUMO

Paddy fields serve as significant reservoirs of soil organic carbon (SOC) and their potential for terrestrial carbon (C) sequestration is closely associated with changes in SOC pools. However, there has been a dearth of comprehensive studies quantifying changes in SOC pools following extended periods of rice cultivation across a broad geographical scale. Using 104 rice paddy sampling sites that have been in continuous cultivation since the 1980s across China, we studied the changes in topsoil (0-20 cm) labile organic C (LOC I), semi-labile organic C (LOC II), recalcitrant organic C (ROC), and total SOC. We found a substantial increase in both the content (48%) and density (39%) of total SOC within China's paddy fields between the 1980s to the 2010s. Intriguingly, the rate of increase in content and density of ROC exceeded that of LOC (I and II). Using a structural equation model, we revealed that changes in the content and density of total SOC were mainly driven by corresponding shifts in ROC, which are influenced both directly and indirectly by climatic and soil physicochemical factors; in particular temperature, precipitation, phosphorous (P) and clay content. We also showed that the δ13 CLOC were greater than δ13 CROC , independent of the rice cropping region, and that there was a significant positive correlation between δ13 CSOC and δ13 Cstraw . The δ13 CLOC and δ13 CSOC showed significantly negative correlation with soil total Si, suggesting that soil Si plays a part in the allocation of C into different SOC pools, and its turnover or stabilization. Our study underscores that the global C sequestration of the paddy fields mainly stems from the substantial increase in ROC pool.


Assuntos
Oryza , Solo , Carbono , China , Geografia
4.
Macromol Rapid Commun ; : e2400299, 2024 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-38850109

RESUMO

Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films have emerged as potential alternatives to indium-tin oxide as transparent electrodes in optoelectronic devices because of their superior transparency, flexibility, and chemical doping stability. However, pristine PEDOT:PSS films show low conductivities because the insulating PSS-rich domains isolate the conductive PEDOT-rich domains. In this study, the conductivities and corresponding spatially resolved Raman properties of PEDOT:PSS thin films treated with various concentrations of H2SO4 are presented. After the PEDOT:PSS films are treated with the H2SO4 solutions, their electrical conductivities are significantly improved from 0.5 (nontreated) to 4358 S cm-1 (100% v/v). Raman heat maps of the peak shifts and widths of the Cα═Cß stretching mode are constructed. A blueshift and width decrease of the Cα═Cß Raman mode in PEDOT are uniformly observed in the entire measurement area (20 × 20 µm2), indicating that microstructural transitions are successfully accomplished across the area from the coiled to linear conformation and high crystallinity upon H2SO4 treatment. Thus, it is proved that comprehensive Raman map analysis can be easily utilized to clarify microstructural properties distributed in large areas induced by various dopants. These results also offer valuable insights for evaluating and optimizing the performance of other conductive thin films.

5.
Environ Res ; 242: 117811, 2024 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-38043896

RESUMO

Clay minerals such as Halloysite nanotubes (HNTs), abundantly available green nanomaterial, exhibit a significant advantage in biomedical applications such as drug delivery, antibacterial and antimicrobials, tissue engineering or regeneration, etc. Because of the mesoporous structure and high absorbability, HNTs exhibit great potential as a nanocarrier in drug delivery applications. The sulfuric acid treatment enhances the surface area of the HNTs and thereby improves their drug-loading capacity by enlarging their lumen space/inner diameter. In the present investigation, based on the literature that supports the efficacy of drug loading after acid treatment, a dual treatment was performed to functionalize the HNTs surface. First, the HNTs were etched and functionalized using sulfuric acid. The acid-functionalized HNTs underwent another treatment using (3-aminopropyl) triethoxysilane (APTES) to better interact the drug molecules with the HNTs surfaces for efficient drug loading. Augmentin, a potential drug molecule of the penicillin group, was used for HNTs loading, and their antibacterial properties, cytotoxicity, and cumulative drug release (%) were evaluated. Different characterization techniques, such as X-ray diffractometer (XRD) and Fourier Transform Infra-Red (FT-IR), confirm the loading of Augmentin to the APTES@Acid HNTs. TEM images confirm the effective loading of the drug molecule with the HNTs. The drug encapsulation efficiency shows 40.89%, as confirmed by the Thermogravimetric Analysis (TGA). Also, the Augmentin-loaded APTES@Acid HNTs exhibited good antibacterial properties against E. coli and S. aureus and low cytotoxicity, as confirmed by the MTT assay. The drug release studies confirmed the sustainable release of Augmentin from the APTES@Acid HNTs. Hence, the treated HNTs can be considered as a potential nanocarrier for effectively delivering Augmentin and promoting enhanced therapeutic benefits.


Assuntos
Combinação Amoxicilina e Clavulanato de Potássio , Nanotubos , Ácidos Sulfúricos , Argila/química , Espectroscopia de Infravermelho com Transformada de Fourier , Staphylococcus aureus , Escherichia coli , Antibacterianos/farmacologia , Nanotubos/química
6.
Proc Natl Acad Sci U S A ; 118(35)2021 08 31.
Artigo em Inglês | MEDLINE | ID: mdl-34453007

RESUMO

Recent research [Wang et al., Nature 581, 184-189 (2020)] indicates nitric acid (NA) can participate in sulfuric acid (SA)-ammonia (NH3) nucleation in the clean and cold upper free troposphere, whereas NA exhibits no obvious effects at the boundary layer with relatively high temperatures. Herein, considering that an SA-dimethylamine (DMA) nucleation mechanism was detected in megacities [Yao et al., Science 361, 278-281 (2018)], the roles of NA in SA-DMA nucleation are investigated. Different from SA-NH3 nucleation, we found that NA can enhance SA-DMA-based particle formation rates in the polluted atmospheric boundary layer, such as Beijing in winter, with the enhancement up to 80-fold. Moreover, we found that NA can promote the number concentrations of nucleation clusters (up to 27-fold) and contribute 76% of cluster formation pathways at 280 K. The enhancements on particle formation by NA are critical for particulate pollution in the polluted boundary layer with relatively high NA and DMA concentrations.


Assuntos
Amônia/química , Dimetilaminas/química , Poluentes Ambientais/química , Poluição Ambiental/análise , Ácido Nítrico/química , Ácidos Sulfúricos/química , Atmosfera , Modelos Químicos , Termodinâmica
7.
Int J Mol Sci ; 25(12)2024 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-38928293

RESUMO

Zr-50Ti alloys are promising biomaterials due to their excellent mechanical properties and low magnetic susceptibility. However, Zr-50Ti alloys do not inherently bond well with bone. This study aims to enhance the bioactivity and bonding strength of Zr-50Ti alloys for orthopedic implant materials. Initially, the surface of Zr-50Ti alloys was treated with a sulfuric acid solution to create a microporous structure, increasing surface roughness and area. Subsequently, low crystalline calcium phosphate (L-CaP) precipitation was controlled by adding Mg2+ and/or CO32- ions in modified simulated body fluid (m-SBF). The treated Zr-50Ti alloys were then subjected to cold isostatic pressing to force m-SBF into the micropores, followed by incubation to allow L-CaP formation. The apatite-forming process was tested in simulated body fluid (SBF). The results demonstrated that the incorporation of Mg2+ and/or CO32- ions enabled the L-CaP to cover the entire surface of Zr-50Ti alloys within only one day. After short-term soaking in SBF, the L-CaP layer, modulated by Mg2+ and/or CO32- ions, formed a uniform hydroxyapatite (HA) coating on the surface of the Zr-50Ti alloys, showing potential for optimized bone integration. After soaking in SBF for 14 days, the bonding strength between the apatite layer and alloy has the potential to meet the orthopedic application requirement of 22 MPa. This study demonstrates an effective method to enhance the bioactivity and bonding strength of Zr-50Ti alloys for orthopedic applications.


Assuntos
Ligas , Líquidos Corporais , Fosfatos de Cálcio , Propriedades de Superfície , Zircônio , Ligas/química , Zircônio/química , Líquidos Corporais/química , Fosfatos de Cálcio/química , Titânio/química , Materiais Biocompatíveis/química , Teste de Materiais , Magnésio/química , Durapatita/química
8.
J Environ Manage ; 359: 120963, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38728980

RESUMO

An efficient recycling process is developed to recover valuable materials from overhaul slag and reduce its harm to the ecological environment. The high temperature sulfuric acid roasting - water leaching technology is innovatively proposed to prepare Li2CO3 from overhaul slag. Under roasting conditions, fluorine volatilizes into the flue gas with HF, lithium is transformed into NaLi(SO4), aluminum is firstly transformed into NaAl(SO4)2, and then decomposed into Al2O3, so as to selective extraction of lithium. Under the optimal roasting - leaching conditions, the leaching rate of lithium and aluminum are 95.6% and 0.9%, respectively. Then the processes of impurity removal, and settling lithium are carried out. The Li2CO3 with recovery rate of 72.6% and purity of 98.6% could be obtained under the best settling lithium conditions. Compared with the traditional process, this work has short flow, high controllability, remarkable technical, economic, and environmental benefits. This comprehensive recycling technology is suitable for overhaul slag, and has great practical application potential for the disposal of other hazardous wastes in electrolytic aluminum industry.


Assuntos
Carbonato de Lítio , Reciclagem , Ácidos Sulfúricos , Ácidos Sulfúricos/química , Reciclagem/métodos , Carbonato de Lítio/química , Alumínio/química , Lítio/química , Água/química
9.
Molecules ; 29(11)2024 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-38893379

RESUMO

The process of transformation of the silicate components of the crystal lattice structure of chrysotile during its quantitative interaction with aqueous solutions containing various stoichiometrically required amounts of sulfuric acid (SRA H2SO4) calculated with respect to the magnesium content in the composition of chrysotile is investigated. It has been shown by IR spectroscopic, X-ray phase, thermal and chemical methods of investigation and analysis that, with quantitative interactions of chrysotile and sulfuric acid, first of all, the "brucite layer" of the molecular structural structure of chrysotile is exposed to acid at SRA H2SO4 = 0.1-0.3. As a result of ion exchange processes, acidic silanol (≡Si-O-H) or disilanol (=Si=(O-H)2) bonds are formed. These acid groups form one-dimensional silicate chains with transverse bridges (≡Si-O-Si≡), where the angles (Si-O-Si = 180 °C) straighten, which are recorded in the IR spectra in the region of characteristic absorption of 1220-1250 cm-1 silica. The association of the resulting acid groups into silicate chains, dimers, and trimers with transverse bridges, leads to the appearance of colloidal silica particles in the system, which cause some inhibition of the dissolution of layered magnesium hydrosilicate in sulfuric acid solutions containing H2SO4 ˃ 0.3 SRA.

10.
Molecules ; 29(5)2024 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-38474501

RESUMO

Banana peel waste is abundant and can be utilized as a low-cost adsorbent for removing toxic Cr (VI) from wastewater. The acid modification of banana peels significantly enhances their adsorption capacity for Cr (VI). An adsorbent was prepared by treating banana peel powder with 50% H2SO4 at 50 °C for 24 h. The acid treatment increased the surface area of the adsorbent from 0.0363 to 0.0507 m2/g. The optimum adsorbent dose was found to be 1 g/L for the complete removal of Cr (VI) from 100 ppm solutions. The adsorption capacity was 161 mg/g based on the Langmuir isotherm model. The adsorption kinetics followed a pseudo-second order model. Increasing the temperature from 20 to 50 °C increased the initial adsorption rate but had a minor effect on the equilibrium adsorption capacity. Thermodynamics studies showed that the process was spontaneous and endothermic. The activation energy was estimated as 24.5 kJ/mol, indicating physisorption. FTIR analyses before and after adsorption showed the involvement of hydroxyl, carbonyl and carboxyl groups in binding the Cr (VI). The Cr (VI) was reduced to Cr (III), which then bound to functional groups on the adsorbent. Desorption under acidic conditions could recover 36% of the adsorbed Cr as Cr (III). No desorption occurred at a neutral pH, indicating irreversible adsorption. Overall, acid-modified banana peel is an efficient, low-cost and eco-friendly adsorbent for removing toxic Cr (VI) from wastewater.

11.
Molecules ; 29(5)2024 Feb 29.
Artigo em Inglês | MEDLINE | ID: mdl-38474576

RESUMO

Surface roughness is a crucial factor that affects the flotation performance of minerals. In this study, the effect of sulfuric acid corrosion on the surface roughness of calcite flotation was investigated through microflotation tests, scanning electron microscopy (SEM-EDS), atomic force microscopy (AFM), Fourier transform infrared (FT-IR) spectroscopy, and contact angle analysis. Microflotation test results show that sulfuric acid treatment has a serious negative effect on the floatability of calcite. When the sulfuric acid dosage was 4 mL (3 mol/L), the flotation recovery of calcite was reduced to less than 19%. SEM-EDS and AFM results verified that the sulfuric acid treatment significantly changed the surface morphology of calcite, reduced the average surface roughness and surface area, and reduced the amount of active Ca2+ sites on the calcite surface. As characterized by FT-IR and contact angle analyses, the sulfuric acid treatment enhanced the hydrophilicity of the calcite surface and reduced the amount of sodium oleate adsorbed on the calcite surface. Consequently, sulfuric acid corrosion can reduce the average surface roughness of calcite and have a serious negative effect on the flotation performance of calcite.

12.
J Comput Chem ; 44(13): 1250-1262, 2023 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-36847779

RESUMO

The nucleation of sulfuric acid-water clusters is a significant contribution to the formation of aerosols as precursors of cloud condensation nuclei (CCN). Depending on the temperature, there is an interplay between the clustering of particles and their evaporation controlling the efficiency of cluster growth. For typical temperatures in the atmosphere, the evaporation of H2 SO4 H2 O clusters is more efficient than the clustering of the first, small clusters, and thus their growth is dampened at its early stages. Since the evaporation rates of small clusters containing an HSO 4 - ion are much smaller than for purely neutral sulfuric acid clusters, they can serve as a central body for the further attachment of H2 SO4 H2 O molecules. We here present an innovative Monte Carlo model to study the growth of aqueous sulfuric acid clusters around central ions. Unlike classical thermodynamic nucleation theory or kinetic models, this model allows to trace individual particles and thus to determine properties for each individual particle. As a benchmarking case, we have performed simulations at T = 300 K a relative humidity of 50% with dipole and ion concentrations of c dipole = 5 × 10 8 - 10 9 cm - 3 and c ion = 0 - 10 7 cm - 3 . We discuss the runtime of our simulations and present the velocity distribution of ionic clusters, the size distribution of the clusters as well as the formation rate of clusters with radii R ≥ 0.85 nm . Simulations give reasonable velocity and size distributions and there is a good agreement of the formation rates with previous results, including the relevance of ions for the initial growth of sulfuric acid-water clusters. Conclusively, we present a computational method which allows studying detailed particle properties during the growth of aerosols as a precursor of CCN.

13.
Anal Biochem ; 681: 115329, 2023 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-37722523

RESUMO

The phenol-sulfuric acid (PSA) method is a widely used colorimetric method for determining the total saccharides. Microplate-based PSA methods have been developed to handle a large number of samples and reduce the use of hazardous chemicals. However, the optimal procedures and measurement conditions for this method have not yet been fully established. To address this gap, we investigated the optimal procedure for microplate-based PSA. In addition to glucose (Glc), two types of cellulose nanofibers (CNFs) were also evaluated as they are a new type of nanomaterial, and a technique to quantify the concentration of CNFs is required in their safety assessment. The results showed that the thermal reaction with sulfuric acid before the addition of phenol resulted in a higher coloration than was shown after the addition of phenol. Furthermore, the longer the resting time after shaking with phenol, the greater the coloration and smaller the variation, with a resting time of 60 min or longer being optimal. This research provides valuable insights into improving the reliability and efficiency of the PSA method, which can facilitate the analysis of saccharides and other substances in a range of applications.


Assuntos
Nanofibras , Fenol , Celulose/química , Reprodutibilidade dos Testes , Fenóis , Carboidratos/análise
14.
Environ Sci Technol ; 57(50): 21168-21177, 2023 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-38051922

RESUMO

Despite its impact on the climate, the mechanism of methanesulfonic acid (MSA) formation in the oxidation of dimethyl sulfide (DMS) remains unclear. The DMS + OH reaction is known to form methanesulfinic acid (MSIA), methane sulfenic acid (MSEA), the methylthio radical (CH3S), and hydroperoxymethyl thioformate (HPMTF). Among them, HPMTF reacts further to form SO2 and OCS, while the other three form the CH3SO2 radical. Based on theoretical calculations, we find that the CH3SO2 radical can add O2 to form CH3S(O)2OO, which can react further to form MSA. The branching ratio is highly temperature sensitive, and the MSA yield increases with decreasing temperature. In warmer regions, SO2 is the dominant product of DMS oxidation, while in colder regions, large amounts of MSA can form. Global modeling indicates that the proposed temperature-sensitive MSA formation mechanism leads to a substantial increase in the simulated global atmospheric MSA formation and burden.


Assuntos
Sulfetos , Oxirredução , Temperatura
15.
Lasers Med Sci ; 38(1): 95, 2023 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-36995426

RESUMO

This study aimed to evaluate the effects of different surface modification methods on the surface roughness, contact angle, and bond strength of composite-veneer materials of polyether-ether-ketone (PEEK). Fifty-five specimens (n = 11) with a size of 7 × 7 × 2 mm were cut out from PEEK discs. The specimens were divided into five groups with different surface treatments: no treatment (NO) (control group), sulfuric acid (SA), plasma (P), femtosecond laser (FS), and Nd-YAG laser (NY). After the surface treatments, the specimens were checked for roughness, contact angle, and bond strength of the composite-veneer material. Data were analyzed with the Welch test for roughness, contact angle, and bond strength parameters. Individual Pearson correlation tests were executed for all surface treatment groups to determine any significant correlations among roughness, contact angle, and bond strength parameters (P < .001). Roughness, contact angle, and bond strength values were affected by surface modification methods (P < .001). In comparison to the control group, NY and FS treatments increased the surface roughness and bond strength; they also provided bond strength values comparable to the SA group. When the relationship between the variables was examined, no correlation was seen between roughness, contact angle, and bond strength values for the NY, SA, and control groups (P > .05); however, significant correlations were determined between the contact angle and surface roughness values for the P and FS groups (P < .05). Femtosecond and Nd-YAG laser treatments are viable surface modification alternatives to the sulfuric acid treatment for the PEEK material.


Assuntos
Colagem Dentária , Lasers de Estado Sólido , Molhabilidade , Propriedades de Superfície , Resinas Compostas/química , Teste de Materiais , Polietilenoglicóis/química , Cetonas/química , Lasers de Estado Sólido/uso terapêutico , Éteres , Resistência ao Cisalhamento
16.
Int J Phytoremediation ; 25(4): 393-402, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-35786072

RESUMO

In this study, the biomass of rubber seed pericarp was first treated with sulfuric acid and then its activated carbon was formed by the pyrolysis process. As produced acid-treated activated carbon of chosen biomass was then used for the adsorption of crystal violet (CV) and methylene green (MG) from the colored aqueous solution. The adsorbent was exposed to several characterization methods to know its structural and morphological behaviors before and after CV and MG adsorption. The adsorbent was found to be mesoporous having a surface area of 59.517 m2/g. The effect of pH, time, and concentration was assessed while various isotherm and kinetics models were employed to know the adsorption insight. The optimum conditions were at pH 8, within 30 min, 50 mg/L concentration, and 0.06 gm dose. The adsorption data (the maximum adsorption capacity for CV and MG were found to be 302.7 and 567.6 mg/g, respectively) was validated by fitting in a response surface statistical methodology and the positive interactions between the studied factors were found. The adsorption was mainly belonging to the electrostatic attraction of the dye molecules. The study proves that the used adsorbent is economical and an excellent source of treating wastewater.


The novelty of this research work comes from the conversion of the abundant biomass waste namely rubber seed pericarp into sulfonated-rich carbon material by pyrolysis process to be an efficient adsorbent for two structurally different cationic dyes. Furthermore, statistical optimization by using response surface methodology was applied to optimize the adsorption key parameters.


Assuntos
Corantes , Poluentes Químicos da Água , Corantes/química , Violeta Genciana/química , Adsorção , Pirólise , Biomassa , Carvão Vegetal/química , Biodegradação Ambiental , Sementes , Cinética , Poluentes Químicos da Água/química , Concentração de Íons de Hidrogênio
17.
Chemistry ; 28(65): e202202171, 2022 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-35975981

RESUMO

The reaction of hexachlorophosphazene, P3 N3 Cl6 , with SO3 and the gold halides AuCl3 and AuBr3 , respectively, leads to the new cyclic anionic tetramer, [S4 N2 O10 ]2- , which is coordinated to Au3+ in the dimeric complexes [Au2 X2 (S4 N2 O10 )2 ] (X=Cl, Br). The [S4 N2 O10 ]2- anion can be seen as the condensation product of two sulfate anions, [SO4 ]2- , and two amidosulfate anions, [NH2 SO3 ]- .

18.
Ecotoxicol Environ Saf ; 243: 114012, 2022 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-36030689

RESUMO

Co-invasion by two invasive plant species (IPS) can occur in the same habitat. Diversified acid deposition may change the co-invasion process by altering litter decomposition and plant-soil feedback signalling. This study examined the co-decomposition of two Asteraceae IPS (Solidago canadensis L. and Bidens pilosa L.) on litter decomposition rate, soil enzyme activities, and soil N-fixing bacterial communities under diversified acid deposition (mixed acid deposition at pH 5.6 and at pH 4.5, sulfuric acid at pH 4.5, and nitric acid at pH 4.5). B. pilosa litter degraded faster than S. canadensis litter. Acid deposition at higher acidity accelerated the decomposition rate of both pure S. canadensis litter and the equally mixed litters from the two Asteraceae IPS. Antagonistic responses may occur during the co-decomposition of the two Asteraceae IPS with mixed acid deposition, regardless of the pH, as well as with nitric acid deposition at pH 4.5; in contrast, there may be neutral responses for the co-decomposition process with sulfuric acid at pH 4.5. The type of acid deposited may be one of the key factors affecting the intensity of the mixing effect affecting the co-decomposition. Acid deposition at higher acidity weakened the antagonistic responses for the co-decomposition of the two Asteraceae IPS compared with the response to weak acids. Together, these results indicate that acid deposition at higher acidity could facilitate the co-invasion of the two Asteraceae IPS mainly through accelerated litter decomposition as well as weakened antagonistic responses for co-decomposition.


Assuntos
Asteraceae , Solidago , Ecossistema , Espécies Introduzidas , Ácido Nítrico , Folhas de Planta , Plantas , Solo/química , Ácidos Sulfúricos
19.
Sensors (Basel) ; 22(14)2022 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-35891035

RESUMO

The sulfuric acid attack is a common form of degradation of reinforced concrete in contact with industrial wastewater, mine water, acid rain, or in sewage treatment stations. In this work, new pH-sensitive IrOx electrodes were developed for monitoring the pH inside mortar or concrete. To test their ability, the pH sensors were embedded in mortar samples at different depths and the samples were exposed to sulfuric acid solution. In another set of experiments, iron wires were placed at the same depths inside similar mortar samples and their corrosion was monitored as the acid attacked the mortar. Severe acid attack led to cement dissolution and formation of gypsum. The new pH sensors succeeded in measuring the pH changes inside the mortars. The pH gradient, from the high acid environment to the high alkaline mortar interior, occurred in a narrow region. Corrosion of the iron electrodes started only when the acidic solution was in their close vicinity.


Assuntos
Materiais de Construção , Aço , Corrosão , Concentração de Íons de Hidrogênio , Ferro , Ácidos Sulfúricos
20.
Int J Mol Sci ; 23(17)2022 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-36076923

RESUMO

The application of immobilized sulfuric acid on silica gel (H2SO4-SiO2) as an efficient and easily reusable solid catalyst was explored in the synthesis of novel α-acyloxycarboxamide derivatives via a Passerini reaction of benzoic acid, aldehyde/ketone, and isocyanides. The Passerini adducts were obtained in high to excellent yields within 10 min in aqueous media under catalytic conditions. The key advantages of the process include a short reaction time, high yields, the catalyst's low cost, and the catalyst's reusability.


Assuntos
Dióxido de Silício , Ácidos Sulfúricos , Catálise , Sílica Gel
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