Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 2.385
Filtrar
1.
Biosens Bioelectron ; 267: 116778, 2024 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-39270363

RESUMO

Establishing an effective system to measure formaldehyde (HCHO) content in food is of great significance due to food safety concern. Inspired by the mechanism of HCHO-induced protein denaturation and its effect on ion/molecule transport in nanochannels, a bioinspired microchannel-based electrochemiluminescence (ECL) sensor was constructed for HCHO detection. Benefiting from the water solubility of HCHO, the molecules rapidly spread and enriched at the ethylenediamine (EDA) functionalized microchannel interface. The reaction between EDA and HCHO significantly increased the negative charge density, leading to enhanced electroosmotic flow (EOF). This enhancement resulted in ion concentration depletion at the microchannel tip and a corresponding decrease in ionic current and ECL intensity. The ECL intensity exhibited a linear dependence on the logarithm of HCHO concentration ranging from 1 pg mL-1 to 100 ng mL-1, with a detection limit of 0.26 pg mL-1(S/N = 3). The biosensor demonstrated high selectivity, successfully detecting HCHO in shrimp samples. The performance of the bioinspired sensor was confirmed through comparation with existing methods, showcasing its superior sensitivity and reliability. The bioinspired sensor provides robust technical support for HCHO detection, crucial for food safety monitoring. Additionally, the innovative combination of bionics and microchannel-based ECL technology broadens the application range of ECL sensors, marking a significant advancement in the field.

2.
Biochem J ; 481(18): 1203-1219, 2024 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-39222030

RESUMO

The AMP-activated protein kinase (AMPK) is a sensor of cellular energy status that is expressed in almost all eukaryotic cells. In the canonical activation mechanism, it is activated by increases in AMP:ATP and ADP:ATP ratios that signify declining cellular energy status. Once activated, AMPK phosphorylates numerous targets that promote catabolic pathways generating ATP, while inhibiting anabolic and other processes that consume ATP, thus acting to restore energy homeostasis. Pharmacological agents that activate AMPK have been useful in identifying downstream targets and have potential as drugs for treatment of metabolic disorders such as Type 2 diabetes and non-alcoholic fatty liver disease. One such agent is C13, a pro-drug with a phosphonate bis(isobutyryloxymethyl) ester moiety, with the isobutyryloxymethyl groups increasing membrane permeability. Following cellular uptake, C13 is cleaved to release C2, an AMP analogue and potent AMPK activator that is specific for complexes containing the α1 (but not the α2) catalytic subunit isoform. This has previously been assumed to be the sole mechanism by which C13 activates AMPK, with potential roles for the isobutyryloxymethyl groups being ignored. We now report that, following cleavage from C13, these protective groups are metabolized to formaldehyde, an agent that inhibits mitochondrial function and increases cellular AMP:ATP ratios, thus providing additional AMPK activation by the canonical mechanism.


Assuntos
Proteínas Quinases Ativadas por AMP , Proteínas Quinases Ativadas por AMP/metabolismo , Humanos , Ativação Enzimática/efeitos dos fármacos , Monofosfato de Adenosina/metabolismo , Monofosfato de Adenosina/farmacologia , Animais , Fosforilação/efeitos dos fármacos , Trifosfato de Adenosina/metabolismo
3.
DNA Repair (Amst) ; 142: 103754, 2024 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-39232366

RESUMO

Transcription reprogramming is essential to carry out a variety of cell dynamics such as differentiation and stress response. During reprogramming of transcription, a number of adverse effects occur and potentially compromise genomic stability. Formaldehyde as an obligatory byproduct is generated in the nucleus via oxidative protein demethylation at regulatory regions, leading to the formation of DNA crosslinking damage. Elevated levels of transcription activities can result in the accumulation of unscheduled R-loop. DNA strand breaks can form if processed 5-methylcytosines are exercised by DNA glycosylase during imprint reversal. When cellular differentiation involves a large number of genes undergoing transcription reprogramming, these endogenous DNA lesions and damage-prone structures may pose a significant threat to genome stability. In this review, we discuss how DNA damage is formed during cellular differentiation, cellular mechanisms for their removal, and diseases associated with transcription reprogramming.


Assuntos
Reprogramação Celular , Dano ao DNA , Transcrição Gênica , Humanos , Animais , Reparo do DNA , Diferenciação Celular , Instabilidade Genômica
4.
J Environ Manage ; 370: 122434, 2024 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-39265492

RESUMO

Photothermal catalytic oxidation is a promising and sustainable method for the degradation of indoor formaldehyde (HCHO). However, the excessively high surface temperature of existing photothermal catalysts during catalysis hinders the effective adsorption and degradation of formaldehyde under static conditions. Catalyst loading and oxygen vacancies (OVs) modulation are commonly employed strategies to reduce the photothermal catalytic temperature and enhance the efficiency of photothermal catalytic oxidation. In this work, a p-n type CuO/TiO2 heterojunction is successfully loaded onto diatomite using a wet precipitation method. Under the irradiation of a 300W xenon lamp, the prepared composite material achieved a 100% removal rate of HCHO within 2 h, with a 98% conversion rate to CO2, surpassing the performance of both individual photocatalysts and thermocatalysts. Additionally, by adjusting conditions such as light irradiation and temperature, we have demonstrated that this material exhibits synergistic photothermal catalytic properties. Based on HRTEM, XPS, Raman, and EPR analyses, the introduction of diatomite as a catalyst support was shown to effectively increase the number of OVs. Experimental results, along with O2-TPD, photoelectrochemical characterization, and radical detection, demonstrate that the presence of OVs enhances the oxidative efficiency of both photocatalysis and thermocatalysis, as well as the UV-Vis-IR photothermal catalytic performance. The ternary composite material generates weak hydroxyl (•OH) and superoxide (•O2-) radical under high-temperature with dark conditions, indicating its catalytic oxidation activity under this condition. The increase in temperature and the expansion of the spectral range both enhance the generation of these radicals. In summary, this work demonstrates that the use of diatomite as a support increases the material's specific surface area and OVs content, thereby enhancing adsorption and photothermal catalysis. It elucidates the enhanced catalytic degradation mechanism of this mineral-based photothermal catalyst.

5.
Angew Chem Int Ed Engl ; : e202413605, 2024 Sep 19.
Artigo em Inglês | MEDLINE | ID: mdl-39297731

RESUMO

Fluorescent foams with interconnected pores are attractive for the detection and quantification of various products. However, many fluorescent probes are suffering from aggregation-caused fluorescence quenching in their solid/aggregated state, are costly, and/or not straightforward to incorporate in foams, limiting their utility for this application. Herein, non-isocyanate polyurethane foams, prepared by the simple water-induced self-blowing process, present a nonconventional fluorescence behaviour, i.e. they are intrinsically fluorescent with a multicolor emission without requiring ex-situ traditional fluorescent probes. These foams demonstrate utility for capturing-sensing gaseous formaldehyde (an emblematic indoor air pollutant), as well as for detecting and quantifying various metal ions (Fe2+, Cu2+, Fe3+, Hg2+). They are also able to selectively sense tetracycline antibiotic in a ratiometric way with a high sensitivity. By exploiting the unique multicolor photoluminescent foam properties, a smartphone-compatible device is used for the facile antibiotic quantification. This nonconventional fluorescence behaviour is discussed experimentally and theoretically, and is mainly based on clusteroluminescence originating from multiple hydrogen bonding and hetero-atomic sub-luminophores, thus from aggregation-induced emission luminogens that are naturally present in the foams. This work illustrates that easily accessible non-conventional fluorescent NIPU foams characterized by a modular emission wavelength have an enormous potential for multiple substrates detection and quantification.

6.
Sci Total Environ ; 954: 176447, 2024 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-39307370

RESUMO

Formaldehyde (HCHO), glyoxal (CHOCHO), and nitrogen dioxide (NO2) are crucial in atmospheric photochemical processes at both surface and elevated altitudes. This study presents synchronous multi-axis differential optical absorption spectroscopy (MAX-DOAS) measurements of the vertical distributions of summertime HCHO, CHOCHO and NO2 in four representative megacities within the Beijing-Tianjin-Hebei (BTH), Yangtze River Delta (YRD), Sichuan Basin (SB), and Pearl River Delta (PRD) regions of China. The vertical distributions of HCHO and CHOCHO tended to occur at higher altitudes compared to NO2, influenced by both primary emissions near the ground and photochemical oxidation processes at elevated altitudes. Source separation regression analysis using the CO-CHOCHO trace pair identified secondary formation as the predominant source of ambient HCHO. In urban areas, the ratio of CHOCHO to secondary HCHO (RGFsec) serves as a more reliable metric at ground level for diagnosing VOC precursor sources, excluding the interference of primary and background HCHO. The increase in RGF values at higher altitudes highlights the relative contribution of VOCs favoring CHOCHO production. Moreover, four indicators (e.g. FNR, FNRsec, GNR, and MNR) were utilized to characterize O3 formation sensitivity at different altitudes. The range of FNR, FNRsec, GNR, and MNR marking the O3 formation sensitivity regime varies regionally, highlighting the need for localized assessments. The VOC-limited regime dominated at the ground level, whereas the contribution of the NOx-limited regime increased with altitude. Therefore, a comprehensive control strategy addressing both VOC and NOx emissions across different altitudes is essential for effectively mitigating photochemical pollution in urban areas of China.

7.
Sci Total Environ ; 953: 176037, 2024 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-39236828

RESUMO

Ozone (O3) pollution has become a noticeable problem in the Chengdu-Chongqing Economic Circle in China. The April-September MDA8 O3 level increases significantly by 2.26 µg m-3 year-1 from 2015 to 2023, with meteorological factors occupying merely 18 % in line with multivariate linear regression. To reveal the impact of anthropogenic emissions on O3 increase, O3 production sensitivity is accurately diagnosed by deriving localized thresholds for satellite formaldehyde (HCHO) to NO2 ratio and validated by in-situ measurements and observation-based model. Tracking volatile organic compounds (VOCs) and NOx through satellite HCHO and NO2, the O3 responses to precursor changes are assessed for long-term and special cases, and appropriate precursor reduction ratios are inferred. The results present that the transition range of satellite HCHO/NO2 from VOC-limited to NOx-limited in the region ranges from 2.7 to 4.3. The VOC-limited regime is concentrated in the urban areas of Chongqing and Chengdu as well as the central of the neighboring cities such as Deyang, Mianyang, and Meishan. The relative incremental reactivity from in-situ observations and box model at three sites in August 2019 demonstrates that O3 is most sensitive to anthropogenic VOC at urban and suburban sites, consistent with satellite results. Satellite and surface NO2 decrease at an annual rate of -2.1 % and - 2.9 % between 2015 and 2023, with larger decreases in Chengdu and Chongqing. In contrast, the trend of satellite HCHO is insignificant, indicating effective reduction in NOx but no significant reduction in VOC. This inappropriate reduction results in an increase in urban O3. The three short-term cases further validate the need for synergistic NOx and VOC reductions. Based on the relationship between O3 and satellite NO2 and HCHO, the minimum and optimal reduction ratios of VOC to NOx are 0.4:1 and 2.4:1 for the entire region, with higher ratios in Chengdu and Chongqing.

8.
Food Chem ; 463(Pt 2): 141128, 2024 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-39276546

RESUMO

To study the alkylresorcinols ability to trap lipid oxidation products in foods, crackers were prepared with either whole grain rye, wheat, spelt, or oat flour, and either sunflower or linseed oil, and were stored for up to 36 days at room temperature. During storage, polyunsaturated fatty acyl chains degraded, malondialdehyde was produced, and alkylresorcinol content decreased. At the end of the storage, alkylresorcinol content in crackers was reduced by 61-78 % and a part of disappeared alkyresorcinols (3-8 %) appeared as malondialdehyde/alkylresorcinol adducts. Formed adducts were unambiguously identified by using synthesized and characterized (NMR, MS) labelled and unlabelled standards, and determined by LC-MS/MS. This ability of alkylresorcinols to trap malondialdehyde, and most likely other lipid oxidation products, might be playing a role in both the reduction of hazardous reactive carbonyls in whole grain foodstuffs and the observed flavor differences between whole and refined grain food products.

9.
Angew Chem Int Ed Engl ; : e202413121, 2024 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-39291296

RESUMO

In this work, we present an innovative and atom-efficient synthesis of trimethine cyanines (Cy3) using formaldehyde (FA) as a single-carbon reagent. The widespread application of Cy3 dyes in bioimaging and genomics/proteomics is often limited by synthetic routes plagued with low atom economy and substantial side-product formation. Through systematic investigation, we have developed a practical and efficient synthetic pathway for both symmetric and asymmetric Cy3 derivatives, significantly minimizing resource utilization. Notably, this approach yields water as the byproduct, in alignment with sustainable chemistry principles. Moreover, the efficient one-pot synthesis facilitates the detection of intracellular FA levels, utilizing the fluorescence signal of Cy3 in live cells. It is also possible to detect the endogenous FA in the intestinal tissues. We observed a significant decrease of FA in the small intestine of the inflammatory bowel disease (IBD) mice compared to the healthy mice. This methodological advancement not only enhances the scope of fluorescent dye synthesis but also contributes to the sustainable practices within chemical manufacturing, offering a significant leap forward in the development of environmentally friendly synthetic strategies.

10.
Vet World ; 17(8): 1836-1845, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-39328437

RESUMO

Background and Aim: Foot-and-mouth disease (FMD) is a highly contagious viral disease of cloven-footed animals. It is a major threat to livestock production worldwide, causing significant economic losses. Inactivation of FMD virus (FMDV) is crucial for vaccine development and control of outbreaks. However, traditional inactivation methods can sometimes damage the viral protein, affecting vaccine efficacy. Therefore, finding new inactivating agents that effectively inactivate the virus while preserving the integrity of its proteins is an important research area. This study investigated the optimal materials (0.04% formaldehyde, 0.001 M binary ethylenimine [BEI], or a combination) for inactivating and preserving the specific molecular weight of Serotype O FMDV protein. Materials and Methods: This study used serotype O FMDV isolated from several areas of East Java. The virus was inoculated into baby hamster kidney-21 cells, and the titer was calculated using the TCID50 Assay. The virus was inactivated using 0.04% formaldehyde, 0.001 M BEI, or a combination of 0.04% formaldehyde and 0.001 M BEI. Inactive viral proteins were characterized using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and western blotting. Results: Serotype O FMDV can be inactivated using 0.04% formaldehyde while preserving specific FMDV proteins, specifically VP0 and VP3 with a molecular weight (MW) of 36 kDa and VP3 with a MW of 24 kDa. Serotype O FMDV can be inactivated by 0.001 M BEI while preserving specific FMDV proteins, specifically VP0 with a MW of 35 kDa, VP3 with a MW of 28 kDa, and VP1 with a MW of 23 kDa. FMDV serotype O can be inactivated using a combination of 0.04% formaldehyde and 0.001 M BEI while preserving specific FMDV proteins, specifically VP0 and VP3 with a MW of 36 kDa and VP3 with a MW of 24 kDa. Conclusion: This study found that 0.04% formaldehyde, alone or in combination with 0.001 M BEI, was effective for inactivating and preserving the specific molecular weight of Serotype O FMDV protein. The limitation of this study was the inactivations of the virus have not yet been tested for their potency on experimental animals. Further research is warranted to investigate the inactivation kinetics of these materials, including their potency on experimental animals. Additionally, a comparison of the inactivation rates between 0.04% formaldehyde alone and the combination with BEI would help to determine the optimal inactivation agent for future applications.

11.
ACS Sens ; 9(9): 4777-4787, 2024 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-39254107

RESUMO

The performance of semiconductor sensors is determined by reaction kinetics, conductivity, and electron mobility, which are undoubtedly closely related to the electron motion behavior. Therefore, the effective regulation of electronic states is crucial for improving gas sensing properties. Previous methods of enhancing the gas-sensing performance have induced complex material modifications, and the extent of performance improvement is usually very limited. Further optimization of the gas sensing performance requires continuous efforts to advance new technologies. Toward this issue, a novel magnetic field-induced strategy is adopted to boost the carrier transfer efficiency of nonferromagnetic semiconductors. The gas sensing investigation results manifest that the applied magnetic field can effectively enhance the sensitivity and reduce the baseline resistance. The In2O3 NC-2 (In2O3 nanocubes) with an applied magnetic field have a greatly enhanced response of 161.4 toward 100 ppm formaldehyde, which is 2.5 times higher than that without magnetic field. The enhanced gas sensing properties can be mainly attributed to magnetization of reactive materials, which makes the orientation of electronic magnetic moments consistent, thus greatly contributing to reactivity. This work introduces a practical approach to effectively improve gas sensing performance without further morphology optimization, noble metal catalysis, structural modification, and material cladding. The results of this study provide new insights for designing novel gas sensors to improve the gas sensing performance.


Assuntos
Campos Magnéticos , Semicondutores , Gases/química , Gases/análise
12.
J Am Heart Assoc ; 13(19): e035341, 2024 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-39291508

RESUMO

BACKGROUND: We aimed to investigate the associations of long-term exposure to ambient formaldehyde with hypertension and angina pectoris symptoms in Chinese adults. METHODS AND RESULTS: Participants' information was obtained from the WHO SAGE (World Health Organization Study on Global Aging and Adult Health) study. The Cox proportional hazards regression model was applied to estimate the associations of formaldehyde with hypertension and angina pectoris symptoms. Mediating effect analysis was used to investigate the mediating effect of hypertension between formaldehyde exposure and angina pectoris symptoms. Long-term exposure to formaldehyde was positively associated with the risk of angina pectoris symptoms (hazard ratio [HR], 1.66 [95% CI, 1.29-2.13], per interquartile range [IQR], 3.33, 1015 molecules/cm2) and hypertension (HR, 1.17 [95% CI, 1.02-1.34], per IQR, 3.34, 1015 molecules/cm2). The associations between formaldehyde and angina pectoris symptoms were greater in participants aged ≥65 years (HR, 1.90 [95% CI, 1.29-2.80]) and in rural areas (HR, 2.71 [95% CI, 1.54-4.77]), whereas the associations of formaldehyde with hypertension were stronger in men (HR, 1.27 [95% CI, 1.02-1.58]), rural areas (HR, 1.22 [95% CI, 0.94-1.59]), and in ever smokers (HR, 1.33 [95% CI, 1.02-1.72]). The mediation effect analysis indicated that 18.44% (95% CI, 2.17-37.65) of the association between formaldehyde exposure and angina pectoris symptoms was mediated by hypertension. CONCLUSIONS: Long-term exposure to ambient formaldehyde was positively associated with hypertension and angina pectoris symptoms. The effects of formaldehyde may be modified by age, sex, urbanicity, and smoking status. Hypertension might play a mediating effect in formaldehyde-induced angina pectoris symptoms.


Assuntos
Angina Pectoris , Formaldeído , Hipertensão , Humanos , Formaldeído/efeitos adversos , Masculino , Feminino , Hipertensão/epidemiologia , Hipertensão/induzido quimicamente , Pessoa de Meia-Idade , Idoso , Angina Pectoris/epidemiologia , Angina Pectoris/induzido quimicamente , Fatores de Tempo , China/epidemiologia , Fatores de Risco , Adulto , Poluentes Atmosféricos/efeitos adversos , Medição de Risco , Organização Mundial da Saúde , Exposição Ambiental/efeitos adversos , Fatores Etários
13.
Environ Sci Technol ; 58(39): 17334-17343, 2024 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-39292760

RESUMO

Carbonyl compounds play a crucial role in the formation of ozone (O3) and secondary aerosols, with recent studies particularly highlighting formaldehyde (HCHO) as a significant contributor to the missing particulate sulfur. However, evaluations based on field observations are limited, especially in clean marine environments. Utilizing observation data from a coastal mountain site in May 2021 in Qingdao, northern China, we reveal the important regulating effect of carbonyls in atmospheric oxidation capacity and particulate sulfur chemistry using detailed chemical box models. Photolysis of gaseous carbonyls accounted for >90% and >60% of the primary sources of HO2 and RO2, respectively, contributing 38% of net O3 production. Notably, HCHO alone constituted 80% of the primary HO2 and 15% of net O3 production. Using a multiphase model with updated HCHO-related chemistry, we determine that HCHO chemistry can account for up to 30% of total particulate sulfur (the sum of hydroxymethanesulfonate and sulfate) and address more than one-third of the simulated sulfate gap. The emission-based multiphase model indicates that the HCHO-related pathway remains significant and can account for 20% of the particulate sulfur under clean marine conditions. These findings underscore the importance of carbonyls, particularly HCHO, in regulating the atmospheric oxidation capacity and particulate sulfur chemistry in the marine atmosphere, urging further laboratory studies on chemical kinetics and field measurements of particle-phase carbonyls.


Assuntos
Atmosfera , Oxirredução , Enxofre , Atmosfera/química , Enxofre/química , Ozônio/química , Poluentes Atmosféricos/química , Aerossóis , China , Material Particulado
14.
Environ Sci Technol ; 58(37): 16368-16375, 2024 Sep 17.
Artigo em Inglês | MEDLINE | ID: mdl-39223712

RESUMO

Assessment of personal formaldehyde (FA) exposure is most commonly carried out using formate as a biomarker, as it is the major product from FA metabolism. However, formate could also have originated from the metabolism of other endogenous and exogenous substances or from dietary intake, which may give rise to overestimated results with regard to FA exposure. We have developed and validated a liquid chromatography-tandem mass spectrometry (LC-MS/MS) coupled with an isotope-dilution method for rigorous quantitation of two major urinary FA conjugation products: thioproline (SPro) and thioprolinyl glycine (SPro-Gly), formed in the reaction between FA and endogenous cysteine or cysteinyl glycine, respectively, as marker molecules to assess personal FA exposure. Using this newly developed method, we measured the FA exposure levels in cigarette smokers, occupants of a chemistry research laboratory and typical domestic household, and visitors to a Chinese temple with a Pearson correlation coefficient greater than 0.94, showing a strong linear correlation between urinary adduct levels and the airborne FA level. It is believed that quantitation of urinary SPro and SPro-Gly may represent a noninvasive, interference-free method for assessing personal FA exposure.


Assuntos
Biomarcadores , Formaldeído , Humanos , Biomarcadores/urina , Formaldeído/urina , Espectrometria de Massas em Tandem , Cromatografia Líquida , Glicina/análogos & derivados , Glicina/urina , Exposição Ambiental , Dipeptídeos/urina , Tiazolidinas/urina
15.
Polymers (Basel) ; 16(17)2024 Aug 24.
Artigo em Inglês | MEDLINE | ID: mdl-39274043

RESUMO

Dental resin composites are widely used in clinical settings but often face longevity issues due to the development and accumulation of microcracks, which eventually lead to larger cracks and restoration failure. The incorporation of microcapsules into these resins has been explored to introduce self-healing capability, potentially extending the lifespan of the restorations. This study aims to enhance the performance of self-healing dental resins by optimizing the microcapsules-resin matrix physicochemical interactions. Poly(urea-formaldehyde) (PUF) microcapsules were reinforced with melamine and subsequently subjected to surface functionalization with 3-aminopropyltriethoxysilane (APTES) and (3-mercaptopropyl)trimethoxysilane (MPTMS). Additionally, microcapsules were functionalized with a bilayer approach, incorporating tetraethyl orthosilicate (TEOS) with either APTES or MPTMS. X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA) confirmed an increased Si:C ratio from 0.006 to 0.165. The functionalization process did not adversely affect the structure of the microcapsules or their healing agent volume. Compared to PUF controls, the functionalized microcapsules demonstrated enhanced healing efficiency, with TEOS/MPTMS-functionalized microcapsules showing the highest performance, showing a toughness recovery of up to 35%. This work introduces a novel approach to functionalization of microcapsules by employing advanced silanizing agents such as APTES and MPTMS, and pioneering bilayer functionalization protocols through their combination with TEOS.

16.
Polymers (Basel) ; 16(17)2024 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-39274095

RESUMO

This paper presents a two-stage microencapsulation process that uses pH modulation to enhance the thermal stability of microcapsules that consist of a melamine-formaldehyde (MF) shell and a butyl stearate core. In the first stage, the pH value was modulated between 6.0 and 8.0. Rising the pH value to 8.0 slowed the polycondensation rate, allowing the MF resin with a lower degree of polymerization to migrate to the capsule surface and form a smooth shell. Lowering the pH value to 6.0 accelerated polycondensation. In the second stage, a relatively fast, continuous reduction in the pH value to 5.0 led to further MF polycondensation, hardening the shell. Post-curing at 100 °C prevented shell damage caused by the liquid-gas phase transition of the core material during the process. The microcapsules produced by increasing the pH value to 8.0 twice demonstrated improved thermal stability, with only a minimal overall weight loss of 5% at 300 °C. Significant weight loss was observed between 350 and 400 °C, temperatures at which the methylene bridges in the MF shell undergo thermal degradation. The results from differential scanning calorimetry, electron microscopy, and thermogravimetry analyses confirmed a successful optimization of the microencapsulation, showing that these microcapsules are promising for thermal energy storage and other applications that require high thermal stability.

17.
Molecules ; 29(17)2024 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-39274907

RESUMO

Catalytic performance decline is a general issue when shaping fine powder into macroscale catalysts (e.g., beads, fiber, pellets). To address this challenge, a phenolic resin-assisted strategy was proposed to prepare porous Co/N carbon beads (ZACBs) at millimeter scale via the phase inversion method followed by confined pyrolysis. Specially, p-aminophenol-formaldehyde (AF) resin-coated zeolitic imidazolate framework (ZIF-67) nanoparticles were introduced to polyacrylonitrile (PAN) solution before pyrolysis. The thermosetting of the coated AF improved the interface compatibility between the ZIF-67 and PAN matrix, inhibiting the shrinkage of ZIF-67 particles, thus significantly improving the void structure of ZIF-67 and the dispersion of active species. The obtained ZACBs exhibited a 99.9% removal rate of tetracycline (TC) within 120 min, with a rate constant of 0.069 min-1 (2.3 times of ZIF-67/PAN carbon beads). The quenching experiments and electron paramagnetic resonance (EPR) tests showed that radicals dominated the reaction. This work provides new insight into the fabrication of high-performance MOF catalysts with outstanding recycling properties, which may promote the use of MOF powder in more practical applications.

18.
MethodsX ; 13: 102937, 2024 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-39295630

RESUMO

A comprehensive risk assessment method was applied to examine the risks associated with airborne formaldehyde occupational exposure among hospital laboratory staff. The method assessed exposure levels and health impacts by integrating area and personal air sampling, biological monitoring, and self-reported health data. Samples were collected from 74 workplaces across various departments using NIOSH method 3500 and were analyzed via UV-vis spectrophotometry. The data showed significant differences in exposure levels between departments (p≤0.05) and confirmed the efficacy of the method in identifying risk differences. Despite average personal exposure levels being measured lower than occupational limits, individual assessments indicated that some participants surpassed these limits, emphasizing the necessity of personal monitoring for workers with higher risks. The high prevalence of respiratory symptoms, such as cough and wheezing among staff, indicated the need for further investigation and targeted interventions. Although estimated cancer and non-cancer risks were within safe thresholds, the study emphasized the importance of continuous exposure monitoring and the implementation of effective control measures in hospital laboratory departments with formaldehyde emission. This integrated method improved the reliability and generalizability of formaldehyde exposure risk assessments and aided in the development of safe occupational health practices.•The method integrated personal and area sampling with advanced calibration for precise occupational exposure evaluation in laboratories.•The method used of biomarkers to assess formaldehyde absorption in the body estimating both cancerous and non-cancerous health risks associated with occupational exposure.•Addressed traditional method limitations and integrated risk components to improve data reliability for workplace safety and health risk management.

19.
Sci Total Environ ; 954: 176197, 2024 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-39277005

RESUMO

Monitoring the spatiotemporal distribution of formaldehyde (HCHO) is crucial for reducing volatile organic compounds (VOCs) emissions, and the long-term evolution of socio-natural sources contributions to tropospheric HCHO over China is still unclear. We propose an oversampling algorithm for quantitatively tracking the evolution of uncertainty, which lowers the uncertainty of the original Level 2 OMI HCHO data (50 % -105 %) to 0-50 %, and then we examine the evolution of contributions from various emissions sources applying multi-scale correlation. We found that the high formaldehyde vertical column densities (VCD) caused by human activities in eastern China are crossing the Hu Huanyong Line, which was formerly used to demarcate the population distribution. National-scale analysis indicate that HCHO VCD are significantly correlated with per capita Gross Domestic Product (per capita GDP) (r = 0.948) and Normalized Difference Vegetation Index (r = 0.864), while no substantial correlation with land surface temperature (LST) (r = 0.233). A valuable finding at city-scale is that the vast majority of cities exhibits clear latitude zoning characteristics in the correlation between HCHO VCD and per capita GDP. Diagnosis at pixel scale reveals that anthropogenic emissions continue to weaken the contributions of emissions caused by the increase in vegetation proportion. NDVI = 0.8 is the critical characteristic point where the contribution of natural source exceeds that of anthropogenic sources, while the point presents a decreasing trend in recent years due to the enhancement of human activities levels. Rise in LST over vegetation areas show positive driving effect on formaldehyde emissions, but continuous urbanization is diminishing this contribution. NDVI = 0.8 is a characteristic point to determine whether the contribution proportion of regional surface temperature to formaldehyde emissions from vegetation begun to rise. Our research identifies the evolutionary process and characteristics of the spatiotemporal distribution and socio-nature sources contributions of tropospheric formaldehyde of China from 2005 to 2022.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA