Search Results (216)

Accurate quantification of iron is essential in biological, chemical, and nanomaterial research, yet commonly used ferrozine-based assays suffer from safety hazards, inconsistent reduction efficiency, and unstable absorbance readings. To address these issues, we systematically optimized the classical protocol and validated improvements that enhance both operational safety and analytical reproducibility. In this work, samples were digested using perchloric acid and hydrogen peroxide, reduced with hydroxylamine, and complexed with ferrozine, with all steps quantitatively evaluated to identify conditions that minimize variability. The optimized assay introduces three key refinements: combining the two traditional hydroxylamine additions into a single reduction step, extending the post-complexation incubation to 2 h to ensure complete formation of the Fe²⁺–ferrozine complex, and performing digestion exclusively in 5 mL screw-cap polypropylene tubes to eliminate tube-bursting events frequently observed with flip-cap formats. Kinetic analysis confirmed that absorbance at 562 nm reaches a stable plateau after 2 h, and the resulting standard curve exhibited excellent linearity (R² = 0.9999). These improvements significantly enhance precision, safety, and ease of implementation. The refined method is broadly applicable and enables reliable quantification of iron in tissues, cultured cells, aqueous solutions, and iron-containing nanomaterials. Full article

Salinity shock severely impairs the partial denitrification/anammox (PD/A) process, leading to prolonged functional deterioration and slow reactivation of anaerobic ammonium-oxidizing bacteria (anammox). To develop an effective strategy for mitigating salinity-induced inhibition, this study systematically examined the role of exogenous hydroxylamine (NH₂OH) in accelerating PD/A recovery using short-term batch assays and long-term reactor operation. Hydroxylamine exhibited a clear concentration-dependent effect on system reactivation. In batch tests, low-dose hydroxylamine (10 mg/L) markedly enhanced anammox activity, increasing the ammonium oxidation rate to 5.5 mg N/(g VSS·h), representing a 42.5% increase, indicating its potential to stimulate key nitrogen-transforming pathways following salinity stress. During continuous operation, hydroxylamine at 5 mg/L proved optimal for restoring reactor performance, achieving stable nitrogen removal with 87% NH₄⁺-N removal efficiency. The nitrite transformation ratio (NTR) reached approximately 80% within 13 cycles, 46 cycles ahead of the control, while simultaneously promoting the enrichment of key functional microbial taxa, including Thauera and Candidatus Brocadia. Hydroxylamine addition also triggered the production of tyrosine- and tryptophan-like proteins within extracellular polymeric substances, which enhanced protective and metabolic functionality during recovery. In contrast, a higher hydroxylamine dosage (10 mg/L) resulted in persistent NO₂⁻-N accumulation, substantial suppression of Candidatus Brocadia (declining from 0.67% to 0.09%), and impaired system stability, highlighting a dose-sensitive threshold between stimulation and inhibition. Overall, this study demonstrates that controlled low-level hydroxylamine supplementation can effectively reactivate salinity-inhibited PD/A systems by enhancing nitrogen conversion, reshaping functional microbial communities, and reinforcing stress-response mechanisms. These findings provide mechanistic insight and practical guidance for improving the resilience and engineering application of PD/A processes treating saline wastewater. Full article

Gelatin-based hydrogels are promising materials for pharmaceutical and biomedical applications due to their biocompatibility, biodegradability, and tunable gel-forming behavior. However, their thermo-sensitivity and limited processability often restrict their practical use in advanced drug delivery or tissue engineering systems. In this study, low-molecular-weight gelatin (LMWG) was obtained from native gelatin through controlled degradation with hydroxylamine, aiming to enhance processability while maintaining functional amino groups for crosslinking. Hydrogels prepared from both native gelatin and LMWG were crosslinked with genipin, a natural and biocompatible compound, and comprehensively characterized in terms of structural, mechanical, and biological properties. LMWG exhibited superior processability, remaining liquid at room temperature, which facilitates the preparation of different formulations and the potential incorporation of bioactive compounds into the crosslinked hydrogels. Compared with gelatin-genipin hydrogels, LMWG-genipin hydrogels showed higher swelling capacity, slightly increased porosity, and improved flexibility without significant loss of mechanical integrity. Rheological analysis confirmed both hydrogels’ viscoelastic properties with differences in their thermo-sensitive behavior. Cytocompatibility assays using L929 fibroblasts demonstrated low toxicity as well as proliferation of cells seeded on the materials. Overall, the combination of molecular weight modulation and crosslinking by genipin provides a simple and effective strategy to develop gelatin-based hydrogels suitable for pharmaceutical formulations, tissue-engineering scaffolds, and controlled-release systems. Full article

Biochar and well-rotted manure are commonly employed materials for sustainable agricultural development, possessing the potential to consistently enhance the yield of monoculture crops. However, their impact on the stability of crop yields in intercropping systems, as well as the microenvironment of the border-row rhizosphere, remains inadequately understood. Consequently, this study utilized corn stover biochar and well-rotted pig manure while minimizing the application of chemical fertilizers to investigate the synergistic effects of biochar and composted manure in augmenting maize yield within a soybean–maize intercropping system and regulating the nitrogen cycle in the border-row rhizosphere under reduced fertilization conditions. In comparison to traditional fertilization, the combination of biochar and manure under reduced fertilization conditions significantly increased the contents of ammonium nitrogen (55%), dissolved organic nitrogen (523%), and particulate organic nitrogen (833%) while simultaneously decreasing the content of mineral-associated organic nitrogen (60%). Additionally, this combination synergistically reduced urease activity (22%) while enhancing the activities of nitrogenase (11%), nitrate reductase (297%), and hydroxylamine reductase (20%). This study establishes a theoretical foundation for elucidating how organically amended materials consistently enhance productivity in intercropping systems and alter nitrogen ecology in border-row rhizospheres, offering new perspectives on sustainable fertilization strategies and crop patterns. Full article

The course of the reactions of acetylenes with fluorinated nitrones in the presence of Zn(OTf)₂ and Et₂Zn was investigated. The formation of hydroxylamines and/or 1,2-oxazolines as products was observed. The desired hydroxylamines were formed as main products if reactions were carried out with the usage of Et₂Zn. In order to explain the obtained results, quantum mechanical calculations of the reaction paths leading to both products were carried out. Further research allowed us to develop the enantioselective variant of described reactions with the usage of enantiomerically pure AziPhenol ligand bearing chiral aziridine scaffold. Full article

The hydroxamic acid moiety is part of many bioactive molecules, including several clinical drugs, which can be constructed through, generally, the parent carboxylic acid and a source of hydroxylamine by a variety of methods. Hydroxamic acids compose a remarkable group of N-hydroxy amides with high capacity to chelate certain transition metal ions such as Fe(III), considered siderophores in Nature, and Ni(II), for instance. During a synthetic program towards the derivatization of natural resinic acids, it was decided to prepare some corresponding hydroxamic acid derivatives with potential biological activity for further studies. There are few reports on hydroxamate-derived terpenoids. It was predicted that adding a hydroxamic acid moiety to the carbon skeleton could enhance the antiproliferative activities or other pharmacological properties, as it occurs in other terpenoid compounds. In this communication, we describe the several issues that we faced in this generally straightforward conversion. Generally, the carboxylic group needs to be activated towards coupling with hydroxylamine. We screened several methods and realized that the desired conversion is difficult in this kind of substrate. After extensive testing, we propose a new protocol via a phosphate intermediate for better results than standard procedures. A basic computational study on the mechanism of this transformation was also carried out to support our experimental results. Full article

Intensive land use in the Argentine Pampas has led to soil degradation, yet links between soil organic matter (SOM) composition, enzyme activity, and fungal communities remain unclear. This study compared contrasting ecoregions and land uses: pristine (PI), pasture (PA), crop rotation with cover crops (RO), and monoculture (MO). Infrared spectra showed that PI soils in Anguil had higher absorbance in hydroxyl/amine (3400 cm⁻¹: 0.90 ± 0.08) and carbonyl (1750 cm⁻¹: 0.52 ± 0.12) bands than MO soils (0.47 ± 0.30 and 0.35 ± 0.06; p < 0.05), indicating greater SOM diversity. Pergamino soils showed smaller differences, reflecting site-specific effects. Enzyme activities also responded to land use. In Anguil, xylosidase, β-1,4-N-acetylglucosaminidase, and phosphatase peaked under PI (40, 127, and 443 nmol g⁻¹ h⁻¹). In Pergamino, xylosidase and β-1,4-N-acetylglucosaminidase were higher under PA and PI, indicating enhanced microbial functionality under low disturbance. Fungal composition varied with land use and location: Mortierellomycetes dominated in Pergamino, while Leotiomycetes and Agaricomycetes were more abundant in PI and PA, and Dothideomycetes increased in MO and RO. Despite compositional shifts, fungal diversity changed little. Integrating chemical, biochemical, and molecular indicators revealed how land-use intensification modifies SOM and microbial processes in Pampas soils. Full article

We investigated the application of an adsorbent fabricated from satsuma mandarin peel biomass using coating with poly(glycidyl methacrylate) followed by sequential treatment with hydroxylamine and hydrochloric acid for the remediation of hexavalent chromium-polluted water. The adsorbent was characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). Batch adsorption experiments were conducted wherein initial solution pH, initial chromium concentration, contact time, and temperature were varied. The adsorption equilibrium experimental data were well simulated by the Langmuir and Jovanovic models, pointing toward the formation of a monolayer of adsorbed chromium ions. The total chromium adsorption capacity of the functionalized satsuma mandarin peel adsorbent reached 219.28 mg g⁻¹ at initial pH 1.4 and 60 °C, markedly higher than 110.23 mg g⁻¹ at 30 °C. Where Cr(VI) was the sole chromium oxidation state in the initial solutions synthesized from potassium dichromate, the presence of Cr(III) ions in the final solutions confirmed Cr(VI) reduction. The results of this study show that the functionalized satsuma mandarin peel biomass is a potential candidate for use in the removal of hexavalent chromium from aqueous solution through reduction-coupled adsorption. Full article

Ammonia-oxidizing bacteria (AOB) are key to the nitrogen cycle, but their resistance to nitrite (NO₂⁻-N) accumulation is unclear. This study examined N.eA1, an AOB from the completely autotrophic nitrogen removal over nitrite (CANON) process, assessing its adaptive responses to NO₂⁻-N. The ammonia oxidation and N₂O emission were evaluated at varying NO₂⁻-N levels, and 3D fluorescence, extracellular polymeric substances (EPS), and soluble microbial products (SMP) analysis were used to probe stress responses. Cellular respiration and key enzyme activities were measured, and proteomics was applied to study protein expression changes. Results showed that higher NO₂⁻-N levels boosted N₂O production, inhibited nitrification, and stimulated denitrification in N.eA1. At 100 mg·L⁻¹ NO₂⁻-N, EPS rose and SMP fell, with ammonia monooxygenase (AMO) suppressed and nitrite reductase (NIR) as well as nitric oxide reductase (NOR) enhanced. Gene expression analysis revealed decreased AMO, hydroxylamine oxidoreductase (HAO), and energy transport-related enzymes, but increased NIR and NOR genes. The downregulation of electron transport complex genes offered insights into molecular adaptation to nitrite stress of N.eA1, highlighting the interplay between metabolic and genetic responses, which is essential for developing sustainable and efficient nitrogen management strategies. Full article

Due to the close association between gut microbiota and diabetes, probiotic dairy products have drawn a lot of attention in the development of functional foods with anti-diabetic activity. In this study, 28 type 2 diabetic patients received 10 g of camel milk powder supplemented with Bifidobacterium animalis A6 (BBA6) twice a day, taking camel milk powder as the placebo. After 4 weeks of intervention, there was a significant decrease in fasting blood glucose, serum content of total cholesterol, and pro-inflammatory cytokines (IL-6, MCP-1). And, in the CA group, the level of irisin and osteocrin increased significantly, while the level of osteonectin also increased, but with no significance. For the adipokines, the intervention of CA decreased the adiponectin, resistin, lipocalin-2, and adipsin levels significantly. Gut microbiota analysis suggested a significant enrichment in the relative abundance of Bifidobacterium when compared with patients supplemented with camel milk powder alone. Furthermore, elevated fecal concentrations of glucose-1-phosphate, conduritol b epoxide, D-Arabitol, dehydroascorbic acid, and dl-p-Hydroxyphenyllactic acid, accompanied with a decrease in glycine, N-Acetylisatin, hydroxylamine, caprylic acid, maltotriose, and guaiacol, were found in patients of group CA. Compared with camel milk alone, the adding of BBA6 can significantly decrease fasting blood glucose in type 2 diabetic patients, while also improving dyslipidemia, chronic inflammation, and skeletal muscle functions, indicating the possibility of probiotic camel milk powder as a dietary treatment that targets metabolic syndromes such as diabetes. Full article

Odorous emissions from hot-mix asphalt (HMA) plants are a growing environmental concern, particularly due to airborne aldehydes and ketones, which have low odor thresholds and a strong sensory impact. This study presents a field-ready analytical method for monitoring odor-active volatile compounds. The system uses dynamic solid-phase microextraction (SPME and SPME Arrow) with on-fiber derivatization via O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) and is coupled to gas chromatography–mass spectrometry (GC–MS) for direct detection. A flow-cell sampling unit enables the real-time capture of aliphatic aldehydes and ketones under transient emission conditions. Calibration using permeation tubes demonstrated sensitivity (limits of detection (LODs) below 0.13 μg/m³), recovery above 85% and consistent reproducibility. Compound identity was confirmed using retention indices and fragmentation patterns. Uncertainty assessment followed ISO GUM (Guide to the Expression of Uncertainty in Measurement) standards, thereby validating the method’s environmental applicability. Field deployment 200 m from an HMA facility identified measurable concentrations that aligned with CALPUFF model predictions. The method’s dual-isomer resolution and 10 min runtime make it ideal for responding to time-sensitive odor complaints. Overall, this approach supports regulatory efforts by enabling high-throughput on-site chemical monitoring and improving source attribution in cases of odor nuisance. Full article

Two pyrene derivatives, substituted at position 1 with isoxazole or NH-pyrazole, were synthesized in 85–87% yield starting from 1-acetylpyrene and via the cyclocondensation reaction of a β-enaminone intermediate with hydroxylamine or hydrazine. The photophysics of the two 5-(1-pyrenyl)-1,2-azoles were explored, revealing that only the isoxazole derivative exhibits good emission properties (ϕ_F ≥ 74%) but without solvatofluorochromism behavior. However, both probes exhibited noticeable photophysics in the aggregated state (in the presence of H₂O and/or in the solid state) and through acid–base interactions (using TFA and TBACN), leveraging the basic and acidic character of the analyzed 1,2-azoles, which was also investigated by ¹H NMR spectroscopy. Therefore, the selective incorporation of N-heteroaromatic units into the pyrene scaffold effectively modulates the photophysics and environmental sensitivity of the corresponding probes. Full article

Formaldehyde vapor (HCHO) is a harmful chemical substance and a potential air contaminant, with a permissible level in indoor spaces below 0.08 ppm (80 ppb). Thus, highly sensitive gas sensors for the continuous monitoring of HCHO are in demand. The electrical conductivity of semiconducting nanomaterials (e.g., single-walled carbon nanotubes (SWCNTs)) makes them sensitive to chemical substances adsorbed on their surfaces, and a variety of portable and highly sensitive chemiresistive gas sensors, including those capable of detecting HCHO, have been developed. However, when monitoring low levels of vapors (<1 ppm) found in ambient air, most chemiresistive sensors face practical issues, including false responses to interfering effects (e.g., fluctuations in room temperature and humidity), baseline drift, and the need to apply a purge gas. Here, we report an actuator-driven, purge-free chemiresistive gas sensor that is capable of reliably detecting 0.05 ppm of HCHO in the air. This sensor is composed of an HCHO→HCl converter (powdery hydroxylamine salt, HA), an HCl detector (a SWCNT-based chemiresistor), and an HCl blocker (a thin plastic plate). Upon exposure to HCHO, the HA emits HCl vapor, which diffuses onto the adjacent SWCNTs, increasing their electrical conductivity through p-doping. Meanwhile, inserting a plastic plate between HA and SWCNTs makes the conductivity of SWCNTs insensitive to HCHO. Thus, via periodic actuation (insertion and removal) of the plastic plate, HCHO can be detected reliably over a wide concentration range (0.05–15 ppm) with excellent selectivity over other volatile organic compounds. This actuator-driven system is beneficial because it does not require a purge gas for sensor recovery or baseline correction. Moreover, since the response to HCHO is synchronized with the actuation timing of the plate, even small (~0.8%) responses to 0.05 ppm of HCHO can be clearly separated from larger noise responses (>1%) caused by interfering effects and baseline drift. We believe that this work provides substantial insights into the practical implementation of nanomaterial-based chemiresistive gas sensors. Full article

Cyclohexylamines are important and valuable key intermediates in the chemical industry, playing a crucial role in the synthesis of a variety of compounds. Developing a low-cost and efficient synthesis route for these chemicals is highly desirable but also presents significant challenges due to the complexity of the reactions involved. Herein, we designed three pathways for the production of 1,3-cyclohexanediamine (1,3-CHDA), including the one-pot reductive amination of resorcinol (RES) with ammonia and molecular hydrogen, the reductive amination of 1,3-cyclohexandione (1,3-CHD) with ammonia, and the oximation–hydrogenation of 1,3-CHD. Through systematical investigation, we finally developed a low-cost, simple operation and an efficient methodology for the synthesis of 1,3-CHDA as follows: RES was firstly hydrogenated in H₂O over Raney Ni to obtain 1,3-CHD, and then the obtained liquid reaction mixture was used directly for the subsequent oximation with hydroxylamine hydrochloride without further purification to form the oxime intermediate, followed by the hydrogenation of the oxime in methanol over Raney Ni to achieve the target product 1,3-CHDA with a high yield. Full article

Amines and hydroxylamines are essential compounds in the synthesis of pharmaceuticals and other functionalized molecules. However, the synthesis of primary amines and particularly hydroxylamines remains a challenging task. The most common way to obtain amines and hydroxylamines involves the reduction of substances containing C-N bonds, such as nitro compounds, nitriles, and oximes. Among these, oximes are the most readily accessible substrates easily derived from ketones and aldehydes. However, oximes are much harder to reduce compared to nitro compounds and nitriles. The catalytic heterogeneous hydrogenation of oximes often requires harsh conditions and catalysts with high precious metal loadings, while hydroxylamines are hard to be obtained by this method. In this work, we showed that Pt supported on a porous ceria–zirconia solid solution enables the selective and atom-efficient synthesis of both hydroxylamines and amines through the hydrogenation of oximes, achieving yields of up to 99% under ambient reaction conditions in a “green” THF:H₂O solvent system. The high activity of the 1% Pt/CeO₂-ZrO₂ catalyst (TOF > 500 h⁻¹) is due to low-temperature hydrogen activation on Pt nanoparticles with the formation of a hydride, Pt-H. The strong influence of electron-donating and electron-withdrawing groups on the hydrogenation of aromatic oximes implies the nucleophilic attack of hydridic hydrogen from Pt to the electrophilic carbon of protonated oximes. Full article