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1.
J Dairy Sci ; 107(1): 62-73, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37709021

RESUMO

Nutritional therapy, which may have advantages over medication, is being investigated as a novel treatment for pregnancy-induced hypertension. Several studies have shown that probiotic yogurt supplementation during pregnancy has beneficial effects on maternal and fetal health. In this study, fermented buffalo milk was produced with yogurt culture and Lactobacillus plantarum B, a probiotic isolated from healthy breast milk with high angiotensin-converting enzyme inhibitory activity. The fermentation conditions under which the angiotensin-converting enzyme (ACE) inhibitory activity reached 84.51% were optimized by the response surface method as follows: 2 × 106 cfu/mL of L. plantarum B, yogurt culture 2.5 × 105 cfu/mL, and 8 h at 37°C. The distribution of ACE inhibitory peptides from fermented buffalo milk and fermented cow milk were further analyzed by liquid chromatography-mass spectrometry. By searching according to the structural features of ACE inhibitory peptides, 29 and 11 peptides containing ACE inhibitory peptide features were found in fermented buffalo milk and fermented cow milk, respectively. To investigate the in vivo antihypertensive activity of fermented buffalo milk, 18 pregnant rats were divided into 3 groups (n = 6 in each group) and administered 10 mL of normal saline, yogurt (20 mg/kg), or labetalol hydrochloride (4 mg/kg) daily from the beginning of pregnancy to parturition. To induce hypertension, methyl nitrosoarginine (125 mg/kg) was injected subcutaneously every day from d 15 of pregnancy to the day of delivery. Blood pressure was not significantly changed in the yogurt and labetalol groups after induction of hypertension and was lower compared with the normal saline group, but there was no difference between the yogurt and labetalol groups. This implied that the buffalo yogurt had a preventive and antihypertensive effect in the pregnancy-induced hypertensive rat model. Further studies to determine the mechanism of action, as well as a randomized control trial, are warranted.


Assuntos
Hipertensão , Labetalol , Lactobacillus plantarum , Probióticos , Humanos , Feminino , Bovinos , Ratos , Animais , Gravidez , Leite/química , Iogurte/análise , Leite Humano/química , Anti-Hipertensivos/farmacologia , Anti-Hipertensivos/análise , Pressão Sanguínea , Labetalol/análise , Solução Salina/análise , Peptídeos/análise , Hipertensão/veterinária , Fermentação , Angiotensinas/análise , Probióticos/análise
2.
Zhongguo Zhong Yao Za Zhi ; 49(5): 1397-1405, 2024 Mar.
Artigo em Chinês | MEDLINE | ID: mdl-38621988

RESUMO

This study employed evidence mapping to systematically sort out the clinical studies about the treatment of premature ventricular contractions with Chinese patent medicines and to reveal the distribution of evidence in this field. The articles about the treatment of premature ventricular contractions with Chinese patent medicines were searched against PubMed, Cochrane Library, Web of Science, CNKI, Wanfang, and VIP with the time interval from January 2016 to December 2022. Evidence was analyzed and presented by charts and graphs combined with text. According to the inclusion and exclusion criteria, 164 papers were included, including 147 interventional studies, 4 observational studies, and 13 systematic reviews. A total of 27 Chinese patent medicines were involved, in which Shensong Yangxin Capsules and Wenxin Granules had high frequency. There were off-label uses in clinical practice. In recent years, the number of articles published in this field showed a decreasing trend. Eight types of outcome indicators were used in interventional studies. Ambulatory electrocardiography, clinical response rate, safety, and echocardiography had high frequency, while the rate of ß-blocker decompensation, major cardiovascular events, and pharmaceutical economic indicators were rarely reported. The evaluation was one-sided. The low quality of the included articles reduced the reliability of the findings. In the future, the clinical use of medicines should be standardized, and the quality of clinical studies should be improved. Comprehensive clinical evaluation should be carried out to provide a sound scientific basis for the treatment of premature ventricular contractions with Chinese patent medicines.


Assuntos
Medicamentos de Ervas Chinesas , Complexos Ventriculares Prematuros , Complexos Ventriculares Prematuros/tratamento farmacológico , Complexos Ventriculares Prematuros/fisiopatologia , Humanos , Medicamentos de Ervas Chinesas/uso terapêutico , Medicamentos sem Prescrição/uso terapêutico
3.
Jpn J Clin Oncol ; 52(7): 707-715, 2022 07 08.
Artigo em Inglês | MEDLINE | ID: mdl-35383373

RESUMO

BACKGROUND: Colorectal cancer is a leading cancer incidence and cause of death worldwide and in Vietnam. Although screening is considered an effective measure to prevent and control colorectal cancer, there is no such effort in Vietnam. METHODS: Between 01 January 2018 and 31 October 2019, a population-based colorectal cancer screening program was conducted in Hanoi, Vietnam. A health advocacy campaign and follow-up phone calls were used to enroll residents aged ≥40 years old to complete an immunochemical-fecal occult blood testing. Positive immunochemical-fecal occult blood testing was followed by a colonoscopy. We also conducted a systematic review of the colorectal cancer screening programs in the Asia-Pacific region that used similar approach by searching Ovid Medline and PubMed databases. RESULTS: During study period, 103 542 individuals among 672 742 eligible residents attended the screening of whom 81.5% participants finished immunochemical-fecal occult blood testing test and the positive rate was 6.1%. The coverage rate for immunochemical-fecal occult blood testing test was 11.9%. Among 2278 individuals who underwent colonoscopy, 3.5% were histologically diagnosed with cancer, 17.8% with advanced adenomas, and 23.1% with non-advanced adenomas. Males had significantly higher detection rate of advanced adenomas, cancer or ≥ two polyps/tumor than females (P < 0.0001). The systematic review showed that in two-step modality (i.e. immunochemical-fecal occult blood testing/fecal immunochemical test and colonoscopy), the test positive was from 4.1 to 10.6%. Once colonoscopy was performed subsequently, the rate of cancer among positive participants was from 1.7 to 16.4% and that of advanced adenomas was from 7.1 to 23.1%. CONCLUSION: We showed that the two-step modality is a promising strategy for colorectal cancer screening in Vietnam that might apply to similar settings with limited resources.


Assuntos
Adenoma , Neoplasias Colorretais , Adenoma/diagnóstico , Adulto , Ásia , Colonoscopia , Neoplasias Colorretais/diagnóstico , Neoplasias Colorretais/epidemiologia , Detecção Precoce de Câncer , Feminino , Humanos , Masculino , Programas de Rastreamento , Sangue Oculto , Vietnã/epidemiologia
4.
Molecules ; 26(3)2021 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-33530612

RESUMO

1-Methyl-3,5-dinitro-2-pyridone serves as an excellent substrate for nucleophilic-type ring transformation because of the electron deficiency and presence of a good leaving group. In this review, we focus on the three-component ring transformation (TCRT) of dinitropyridone involving a ketone and a nitrogen source. When dinitropyridone is allowed to react with a ketone in the presence of ammonia, TCRT proceeds to afford nitropyridines that are not easily produced by alternative procedures. Ammonium acetate can be used as a nitrogen source instead of ammonia to undergo the TCRT, leading to nitroanilines in addition to nitropyridines. In these reactions, dinitropyridone serves as a safe synthetic equivalent of unstable nitromalonaldehyde.


Assuntos
Compostos Heterocíclicos/síntese química , Nitrogênio/química , Piridonas/química , Acetatos/química , Compostos Heterocíclicos/química , Cetonas/química , Estereoisomerismo
5.
Angew Chem Int Ed Engl ; 59(46): 20455-20458, 2020 11 09.
Artigo em Inglês | MEDLINE | ID: mdl-33448556

RESUMO

The enantioselective desymmetrizing C-H activation of α-gem-dialkyl acyclic amides remains challenging because the availability of four chemically identical unbiased methylene C(sp3)-H bonds and increased rotational freedoms of the acyclic systems add tremendous difficulties for chemo- and stereocontrol. We have developed a method for the synthesis of acyclic aliphatic amides with α,ß-contiguous stereogenic centers via PdII-catalyzed asymmetric arylation of unbiased methylene C(sp3)-H, in good yields and with high levels of enantio-, chemo- and diastereoselectivity (up to >99 % ee and >20:1 d.r.). Successive application of this method enables the sequential arylation of the gem-dialkyl groups with two different aryl iodides, giving a range of ß-Ar1-ß'-Ar2-aliphatic acyclic amides containing three contiguous stereogenic centers with excellent diastereoselectivity.

6.
Angew Chem Int Ed Engl ; 59(33): 14060-14064, 2020 08 10.
Artigo em Inglês | MEDLINE | ID: mdl-32391972

RESUMO

Herein, we describe an unprecedented cascade reaction to ß-stereogenic γ-lactams involving Pd(II)-catalyzed enantioselective aliphatic methylene C(sp3 )-H alkenylation-aza-Wacker cyclization through syn-aminopalladation. Readily available 3,3'-substituted BINOLs are used as chiral ligands, providing the corresponding γ-lactams with broad scope and high enantioselectivities (up to 98 % ee).

7.
J Environ Manage ; 246: 374-383, 2019 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-31195257

RESUMO

The exponential washoff model was originally developed based on observations of particulate pollutants, however, its applicability when applied to different forms of pollutants is not well understood. Data from a previous study of 6 stormwater pollutants from 126 events at 12 sites in Singapore was used for event based model parameter calibration using a Monte Carlo technique. The accuracy of the calibrated exponential washoff model was clearly best for particulate pollutant total suspended solids (TSS), and worst for dissolved pollutants Ortho-Phosphate (PO4), nitrate (NO3) and ammonium-nitrogen (NH4). Model accuracy for mixed forms of pollutants total Phosphorus (TP) and total Nitrogen (TN) were in between these two extremes. Relationships between model parameters with rainfall and flow characteristics were also investigated. Statistically significant relationships could only be found for TSS, where the total rainfall depth was identified as being the most significant variable to explain model parameter behaviour. Antecedent dry period (ADP) was shown to have little or no importance across all land uses and pollutant forms. The results showed that the model parameter behaviour could be explained only for particulate pollutants and small (≤10 ha) sub-catchments, and that replicating washoff of mixed or dissolved forms of pollutants as a fraction of solids is likely to lead to misleading results.


Assuntos
Poluentes Ambientais , Poluentes Químicos da Água , Monitoramento Ambiental , Fósforo , Chuva , Singapura , Movimentos da Água
8.
Biochem Biophys Res Commun ; 469(2): 203-9, 2016 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-26631967

RESUMO

1-aminocyclopropane-1-carboxylic acid (ACC) synthase (ACS) is a rate-limiting enzyme in the biosynthesis of ethylene which regulates many aspects of the plant development and responses to biotic and abiotic stresses. In this study, a full-length cDNA of ACC synthase, OnACS2, was cloned from the senescing flower of Oncidium Gower Ramsey by RACE. The full-length cDNA of OnACS2 (GenBank accession no. JQ822087) was 1557 bp in length with an open reading frame (ORF) of 1308 bp encoding for a protein of 435 amino acid residues. The predicted OnACS2 protein had a molecular mass of 49.1 kDa with pI value of 7.51. Phylogenetic analysis indicated its evolutionary relationships with corresponding orthologous sequences in orchids, Hosta ventricosa and monocots. Real-time PCR assay demonstrated that OnACS2 was constitutively expressed in all tested organs with the highest transcript level in the gynandria. Differential expression pattern of OnACS2 gene correlated to the ethylene production and the subsequent occurrence of senescent symptoms in flower suggested that OnACS2 probably played an important role in the initiation of flower senescence.


Assuntos
Escherichia coli/fisiologia , Etilenos/biossíntese , Liases/química , Liases/fisiologia , Orchidaceae/enzimologia , Orchidaceae/genética , Sequência de Aminoácidos , Senescência Celular/fisiologia , Clonagem Molecular/métodos , Ativação Enzimática , Escherichia coli/citologia , Flores/enzimologia , Flores/genética , Dados de Sequência Molecular , Reguladores de Crescimento de Plantas/biossíntese
9.
Org Biomol Chem ; 14(45): 10674-10682, 2016 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-27790667

RESUMO

When 2-(phenylethynyl)pyridine was oxidized, the formed N-oxide immediately cyclized at the ethynyl group to form isoxazolo[2,3-a]pyridinium salt. This salt underwent Reissert-Henze-type reactions with alcohol in the presence of a base to afford 6-substituted 2-phenacylpyridines, which are not easily synthesized through alternative procedures. When acetonitrile was used as a solvent, an amide functional group was introduced into the phenacylpyridine framework. Moreover, a hetero-atom at the 6-position facilitated the oxidation of the phenacyl group to afford α-diketones upon simple exposure of the reaction mixture to air.

10.
Molecules ; 21(7)2016 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-27347919

RESUMO

A metal-free, mild and efficient method for the synthesis of 2-methylquinolines was successfully developed by condensation of anilines with vinyl ethers in the presence of catalytic amount of iodine. Modification of both pyridine and benzene moieties was easily achieved by changing only the vinyl ether and aniline. In this reaction, the iodine species was revealed to show dual behavior; molecular iodine serves as an oxidant, while its reduced form, hydrogen iodide, activates the vinyl ether. The redox reaction between these iodine species enables the use of a catalytic amount of iodine in this synthetic method.


Assuntos
Compostos de Anilina/química , Iodo/química , Quinaldinas/química , Compostos de Vinila/química , Catálise , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Oxirredução , Quinaldinas/síntese química
11.
J Org Chem ; 80(17): 8856-8, 2015 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-26244697

RESUMO

An alternative method for the synthesis of 3-alkylated/arylated 5-nitropyridines was developed involving a three-component ring transformation of 3,5-dinitro-2-pyridone on treatment with aldehyde in the presence of ammonium acetate. This method facilitates the modification of the substituent at the 3-position by changing the precursor aldehyde. The use of solid ammonium acetate instead of ammonia as the nitrogen source renders the synthetic method more practical and user-friendly.

12.
Org Lett ; 26(21): 4457-4462, 2024 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-38775281

RESUMO

Desymmetrization of gem-dimethyl groups has been developed as an efficient pathway to achieve asymmetric C(sp3)-H functionalization. Herein, we described a Pd(II)-catalyzed desymmetrizing gem-dimethyl C(sp3)-H alkenylation/aza-Wacker cyclization directed by a bidentate 2-pyridinylisopropyl auxiliary. Chiral α-methyl γ-lactams were obtained in good yields (up to 82%) and high enantioselectivities (up to 91.5% ee).

13.
Environ Sci Process Impacts ; 25(11): 1830-1838, 2023 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-36987664

RESUMO

Per- and polyfluoroalkyl substances (PFAS) are emerging contaminants that have been used extensively as firefighting agents and in a wide range of commercial applications around the world. As many of the most-common PFAS components are surfactants, they readily accumulate at interfaces, a process that can govern their environmental fate. There are thousands of PFAS compounds, and they have nearly always been used as mixtures, so it is common to find many different PFAS components present together in the environment. Furthermore, the interfacial behavior of ionic PFAS can be strongly influenced by the presence of salts, with adsorption dependent on both the composition and concentration of salts present. Any predictions of PFAS interfacial behavior made without considering both the mixed nature of PFAS present, as well as the composition of the salts present, have the potential to be off by orders of magnitude. To date, models capable of making predictions of PFAS interfacial adsorption when both mixed PFAS and mixed salts are present have not been presented. The work described here addresses this need by extending a mass-action model developed previously by the authors to allow predictions in cases where complex combinations of mixed PFAS and mixed salts are present. Predictions of PFAS interfacial affinity for a range of PFAS mixture conditions and ionic strengths are verified using experimentally-measured surface tension data. The new model provides physically-realistic prediction of interfacial adsorption of a wide range of PFAS mixtures over a wide range of salt concentrations and compositions. The model is capable of predicting interfacial adsorption of ionic/nonionic PFAS mixtures in the presence of salts, and can also make predictions when there is competitive adsorption between different PFAS components, a common case in PFAS source zones where high concentrations of multiple components are present and in foam fractionation reactors.


Assuntos
Fluorocarbonos , Sais , Adsorção , Tensão Superficial , Tensoativos , Água
14.
Sci Total Environ ; 902: 166111, 2023 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-37567299

RESUMO

Shrimp farming has strongly developed in recent years, and became an important economic sector that helps create jobs and increase incomes for Vietnamese. However, the aquatic environment has also been greatly affected by the development due to the amount of wastewater discharged from shrimp farms. Among biological processes used for treating shrimp farming wastewater, the application of microalgae-bacteria co-culture is considered high potential due to its treatment and energy saving. Consequently, a photobioreactor operated with microalgae-bacteria co-culture was employed to treat shrimp farming wastewater. The salinity of wastewater and the operating condition (ratio of biomass retention time and hydraulic retention time, BRT/HRT) are the major factors affecting pollutant removal. Thus, this study investigated the effects of salinities of 0.5-20 ppt and BRT/HRT ratios of 1.5-16 on the removal performance. The results indicated that the nutrient removal was reduced when PBR operated under salinity over than 10 ppt and BRT/HRT over 5.5. Particularly, the nitrogen and phosphorus removal rates were achieved 6.56 ± 1.33 gN m-3 d-1 and 1.49 ± 0.59 gP m-3 d-1, and the removal rates decreased by 2-4 times under a salinity >10 ppt and 2-6 times under a BRT/HRT ratio >5.5. Whereas, organic matter treatment seems not to be affected when the removal rate was maintained at 28-34 gCOD m-3 d-1 under various conditions.


Assuntos
Microalgas , Águas Residuárias , Simbiose , Salinidade , Bactérias , Agricultura , Biomassa , Nitrogênio/análise , Fósforo
15.
Sci Total Environ ; 899: 165595, 2023 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-37467995

RESUMO

Floating treatment wetlands (FTW) are nature-based solutions for the purification of open water systems such as rivers, ponds, and lakes polluted by diffuse sources as untreated or partially treated domestic wastewater and agricultural run-off. Compared with other physicochemical and biological technologies, FTW is a technology with low-cost, simple configuration, easy to operate; has a relatively high efficiency, and is energy-saving, and aesthetic. Water remediation in FTWs is supported by plant uptake and the growth of a biofilm on the water plant roots, so the selection of the macrophyte species is critical, not only to pollutant removal but also to the local ecosystem integrity, especially for full-scale implementation. The key factors such as buoyant frame/raft, plant growth support media, water depth, seasonal variation, and temperature have a considerable role in the design, operation, maintenance, and pollutant treatment performance of FTW. Harvesting is a necessary process to maintain efficient operation by limiting the re-pollution of plants in the decay phase. Furthermore, the harvested plant biomass can serve as a green source for the recovery of energy and value-added products.


Assuntos
Poluentes Químicos da Água , Áreas Alagadas , Ecossistema , Eliminação de Resíduos Líquidos , Poluentes Químicos da Água/análise , Biodegradação Ambiental , Plantas , Água , Nitrogênio/análise
16.
Cancer Epidemiol Biomarkers Prev ; 32(9): 1160-1168, 2023 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-37314746

RESUMO

BACKGROUND: Colorectal cancer is one of the leading cancers worldwide and in Vietnam. Adenomas are important precursors of colorectal cancer. Study on the association between sleep duration and development of colorectal adenoma (CRA) is limited, particularly among Vietnamese population. METHODS: We conducted an individually matched case-control study of 870 CRA cases and 870 controls in a large-scale colorectal screening program involving 103,542 individuals ages ≥40 years old in Hanoi, Vietnam. Sleep duration was categorized in three groups: short: ≤6 hours/day, normal: 7 to 8 hours/day, and long: >8 hours/day. Conditional logistic regression was used to evaluate the association between sleep duration and adenomas risk after controlling for potential confounders. RESULTS: Overall, short-sleep duration was associated with increased risk of having CRA compared with normal duration [OR, 1.48; 95% confidence interval (CI), 1.12-1.97]. This pattern was present in both females (OR, 1.58; 95% CI, 1.14-2.18) and males (OR, 1.45; 95% CI, 1.08-1.93), with advanced adenomas (OR, 1.61; 95% CI, 1.09-2.38) and non-advanced adenomas (OR, 1.66; 95% CI, 1.19-2.32). Furthermore, the association between CRA development and short-sleep duration was more apparent among females who were nondrinker, nonobese, physically active, with proximal or both sided adenomas and with cardiometabolic disorder. Among males, the short-sleep duration was associated with CRA risk among never-smoking, cardiometabolic disorders, and obese. CONCLUSIONS: Short-sleep duration was associated with increased prevalence of both advanced and non-advanced CRAs among Vietnamese population. IMPACT: Findings from this study showed that maintaining an adequate sleep duration may have an important implication for colorectal adenoma prevention and control.


Assuntos
Adenoma , Doenças Cardiovasculares , Neoplasias Colorretais , Masculino , Feminino , Humanos , Adulto , Estudos de Casos e Controles , Fatores de Risco , Duração do Sono , Vietnã/epidemiologia , Neoplasias Colorretais/epidemiologia , Neoplasias Colorretais/etiologia , Neoplasias Colorretais/prevenção & controle , Adenoma/epidemiologia , Adenoma/etiologia , Adenoma/prevenção & controle , Colonoscopia
17.
Chemosphere ; 305: 135376, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35716714

RESUMO

1,2-dichloroethane (1,2-DCA) is a chlorinated hydrocarbon used for polyvinyl chloride plastic production. As such, 1,2-DCA is a common persistent contaminant in saturated zones. While nanoscale zerovalent iron (NZVI) is considered an effective reductant for removing a wide range of chlorinated hydrocarbons, 1,2-DCA is resistant to reduction by NZVI as well as by modified forms of NZVI (e.g., sulfidated-NZVI). Hydroxyl radicals produced in Fenton's reaction can effectively degrade 1,2-DCA, but Fenton's reaction requires the acidification of saturated zones to achieve a groundwater pH of 3 to facilitate the catalytic reaction. To overcome this problem, this study has developed a sequential treatment process using an NZVI-induced Fenton-like reaction that can effectively degrade 1,2-DCA at an initially neutral pH range. The experiments were conducted using a high 1,2-DCA concentration (2000 mg/L) to evaluate the feasibility of using the treatment process at source zones. The process degraded 99% of 1,2-DCA with a pseudo-first-order rate constant of 0.49 h-1. Unlike the single-stage treatment process, the sequential treatment can control the used H2O2 concentration in the system, thus sustaining the reaction and resulting in more efficient 1,2-DCA degradation. To mimic subsurface conditions, batch experiments were conducted to remove 1,2-DCA sorbed in contaminated soil. The results show that 99% removal of 1,2-DCA was obtained within 16 h. Additionally, this study suggests that the NZVI can be used for at least three consecutive 1,2-DCA degradation cycles while maintaining high removal efficiency.


Assuntos
Ferro , Poluentes Químicos da Água , Dicloretos de Etileno , Peróxido de Hidrogênio , Concentração de Íons de Hidrogênio , Poluentes Químicos da Água/análise
18.
Sci Total Environ ; 819: 151987, 2022 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-34843785

RESUMO

Salts are known to have strong impacts on environmental behavior of per- and polyfluoroalkyl substances (PFAS) including air-water interfacial adsorption. Multivalent salts impact interfacial adsorption to a greater extent than monovalent salts. Models to make a priori predictions of PFAS interfacial adsorption in the presence of multiple salts with different ionic charges are needed given the need to predict PFAS environmental fate. This study further develops a mass-action model to predict the interfacial behavior of PFAS as a function of both salt valency and concentration. The model is validated using surface tension data for a series of monovalent and divalent salt mixtures over a wide range of ionic strengths (i.e., from no added salt to 0.5 M) as well as comparison to data from literature. This model highlights the disproportionate impact of multivalent salts on interfacial adsorption and the practical utility of the model for predicting interfacial adsorption in the presence of multiple monovalent and multivalent inorganic salts. Results suggest that failure to account for divalent salt, even when concentrations are much smaller than monovalent salt, under most environmentally relevant aqueous phase conditions will result in significant underpredictions of PFAS interfacial adsorption. Simple examples of PFAS distribution in a range of salt conditions in the vadose zone and in aerated-water treatment reactors highlight the predictive utility of the model.


Assuntos
Fluorocarbonos , Adsorção , Cloreto de Sódio , Tensão Superficial
19.
Polymers (Basel) ; 14(15)2022 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-35893997

RESUMO

Parylene is used as encapsulating material for medical devices due to its excellent biocompatibility and insulativity. Its performance as the insulating polymer of implantable neural interfaces has been studied in electrolyte solutions and in vivo. Biological tissue in vitro, as a potential environment for characterization and application, is convenient to access in the fabrication lab of polymer and neural electrodes, but there has been little study investigating the behaviors of Parylene in the tissue in vitro. Here, we investigated the electrochemical impedance behaviors of Parylene C polymer coating both in normal saline and in a chilled pig brain in vitro by performing electrochemical impedance spectroscopy (EIS) measurements of platinum (Pt) wire neural electrodes. The electrochemical impedance at the representative frequencies is discussed, which helps to construct the equivalent circuit model. Statistical analysis of fitted parameters of the equivalent circuit model showed good reliability of Parylene C as an insulating polymer in both electrolyte models. The electrochemical impedance measured in pig brain in vitro shows marked differences from that of saline.

20.
Sci Total Environ ; 848: 157663, 2022 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-35907553

RESUMO

Per- and polyfluoroalkyl substances (PFAS) are widely-detected environmental contaminants known to concentrate at surfaces and interfaces. Many of the most commonly-detected PFAS function as ionic surfactants under environmental conditions. The interfacial behaviors of ionic surfactants, including PFAS, are strongly dependent on salt concentration and composition, with interfacial affinity potentially varying by orders of magnitude for the same compound under different conditions. The work described here presents a tool for predicting the salt-dependent adsorption of PFAS compounds based entirely on chemical structure, something of great value for predicting the real-world environmental behavior of many of the large numbers of PFAS compounds for which experimental data are not available. The approach combines two different previously-developed models, one a mass-action model designed to predict the effects of salts on interfacial adsorption of ionic PFAS (the UNSW-OU salt model), and the second a group-contribution model designed to predict interfacial adsorption of PFAS in the absence of salt based on chemical structure. The challenge of combining the two models comes from the fact that both are based on different isotherms. The salt model can produce sigmoidal isotherms under salt-limited conditions (an isotherm shape that is supported by experimental evidence), while the group-contribution model can generate Langmuir parameters from calculations based on chemical structure. Equations were derived to determine salt model isotherm parameters from Langmuir parameters (either from the group-contribution model or experimental sources) by matching surface tension curves in the vicinity of the concentration of highest second derivative. Refined group-contribution model parameters were determined based on data from an additional 40 surface tension curves to allow improved structure-based predictions for important classes of PFAS that were not sufficiently well-represented in the original model. The resulting equations provide a tool allowing quantitative predictions of PFAS behavior under realistic environmental conditions for compounds for which little or no experimental data are available.


Assuntos
Fluorocarbonos , Adsorção , Sais , Cloreto de Sódio , Tensoativos/química , Água/química
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