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1.
Environ Monit Assess ; 196(5): 435, 2024 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-38587761

RESUMO

Simple and sensitive electrochemical sensors were fabricated from cerium oxide (CeO2) and copper-benzene tricarboxylic acid-modified cerium oxide (CeO2-Cu-BTC) materials for differential pulse voltammetric analysis of toxic cadmium (Cd) ions in aqueous solutions. The materials were prepared by hydrothermal method and structurally characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy with energy-dispersive X-ray (SEM-EDX), thermogravimetric analysis (TGA), and X-ray diffraction analysis (XRD). The CeO2-modified carbon paste electrode (CeCPE) and the CeO2-Cu-BTC-modified carbon paste electrode (CeBCPE) were electrochemically characterized by their cyclic voltammetry and electrochemical impedance study in standard K3[Fe(CN)6] single-electron redox process. Their electrochemical surface areas, electrode surface coverages, and charge transfer resistances were calculated to be 1.46 cm2, 2.338 × 10-5 mol∙cm-2, and 2790 Ω and 5.48 cm2, 2.476 × 10-5 mol∙cm-2, and 1254.65 Ω for CeCPE and CeBCPE, respectively. These fabricated electrodes were used as electrochemical sensors for cadmium ion estimation by optimizing the experimental parameters through differential pulse voltammetry. The optimized conditions included 10% modifier for CeCPE and 5% modifier for CeBCPE in 0.12 M HCl solution of pH 5 as supporting electrolyte at - 1.2 V deposition for 30 s in 0.01 to 10 mg L-1 linear cadmium solution range. Under these conditions, the limit of quantification (LOQ) of 0.368 mg L-1 and 0.005 mg L-1 was calculated for CeCPE and CeBCPE electrodes, respectively. The limit of detection (LOD) was calculated to be 0.121 mg L-1 and 0.002 mg L-1 for CeCPE and CeBCPE, respectively. All the experimental results indicated that electrodes fabricated from CeO2-Cu-BTC show better performance as compared to CeO2-based electrodes. Both these types of electrochemical sensors presented good repeatability and performance in the presence of interfering ions as well. From these findings, it can also be inferred that these electrochemical sensors can provide a simple and very sensitive method for approximation of toxic cadmium ions in aqueous solutions.


Assuntos
Cádmio , Cério , Cobre , Cicloexanos , Monitoramento Ambiental , Íons , Carbono
2.
Analyst ; 149(8): 2388-2398, 2024 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-38462973

RESUMO

Hydrogen/deuterium exchange mass spectrometry (HDX-MS) is a versatile bioanalytical technique for protein analysis. Since the reliability of HDX-MS analysis considerably depends on the retention of deuterium labels in the post-labeling workflow, deuterium/hydrogen (D/H) back exchange prevention strategies, including decreasing the pH, temperature, and exposure time to protic sources of the deuterated samples, are widely adopted in the conventional HDX-MS protocol. Herein, an alternative and effective back exchange prevention strategy based on the encapsulation of a millimeter droplet of a labeled peptide solution in a water-immiscible organic solvent (cyclohexane) is proposed. Cyclohexane was used to prevent the undesirable uptake of water by the droplet from the atmospheric vapor through the air-water interface. Using the pepsin digest of deuterated myoglobin, our results show that back exchange kinetics of deuterated peptides is retarded in a millimeter droplet as compared to that in the bulk solution. Performing pepsin digestion directly in a water-in-oil droplet at room temperature (18-21 °C) was found to preserve more deuterium labels than that in the bulk digestion with an ice-water bath. Based on the present findings, it is proposed that keeping deuterated peptides in the form of water-in-oil droplets during the post-labelling workflow will facilitate the preservation of deuterium labels on the peptide backbone and thereby enhance the reliability of the H/D exchange data.


Assuntos
Pepsina A , Água , Deutério/química , Reprodutibilidade dos Testes , Espectrometria de Massas/métodos , Medição da Troca de Deutério/métodos , Peptídeos/química , Hidrogênio/química , Mioglobina/química , Cicloexanos
3.
PLoS One ; 19(3): e0288953, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38489327

RESUMO

In this study, we intensively measured the longitudinal productivity and survival of 362 commercially managed honey bee colonies in Canada, over a two-year period. A full factorial experimental design was used, whereby two treatments were repeated across apiaries situated in three distinct geographic regions: Northern Alberta, Southern Alberta and Prince Edward Island, each having unique bee management strategies. In the protein supplemented treatment, colonies were continuously provided a commercial protein supplement containing 25% w/w pollen, in addition to any feed normally provided by beekeepers in that region. In the fumagillin treatment, colonies were treated with the label dose of Fumagilin-B® each year during the fall. Neither treatment provided consistent benefits across all sites and dates. Fumagillin was associated with a large increase in honey production only at the Northern Alberta site, while protein supplementation produced an early season increase in brood production only at the Southern Alberta site. The protein supplement provided no long-lasting benefit at any site and was also associated with an increased risk of death and decreased colony size later in the study. Differences in colony survival and productivity among regions, and among colonies within beekeeping operations, were far larger than the effects of either treatment, suggesting that returns from extra feed supplements and fumagillin were highly contextually dependent. We conclude that use of fumagillin is safe and sometimes beneficial, but that beekeepers should only consider excess protein supplementation when natural forage is limiting.


Assuntos
Cicloexanos , Ácidos Graxos Insaturados , Mel , Abelhas , Animais , Estações do Ano , Suplementos Nutricionais , Alberta , Sesquiterpenos
5.
Environ Pollut ; 345: 123460, 2024 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-38290655

RESUMO

Despite the increasing production, use, and ubiquitous occurrence of novel brominated flame retardants (NBFRs), little information is available regarding their fate in aquatic organisms. In this study, the bioaccumulation and biotransformation of two typical NBFRs, i.e., 1,2-bis (2,4,6-tribromophenoxyethane) (BTBPE) and 1,2-dibromo-4-(1,2-dibromoethyl)-cyclohexane (TBECH), were investigated in tissues of zebrafish (Danio rerio) being administrated a dose of target chemicals through their diet. Linear accumulation was observed for both BTBPE and TBECH in the muscle, liver, gonads, and brain of zebrafish, and the elimination of BTBPE and TBECH in all tissues followed pseudo-first-order kinetics, with the fastest depuration rate occurring in the liver. BTBPE and TBECH showed low bioaccumulation potential in zebrafish, with biomagnification factors (BMFs) < 1 in all tissues. Individual tissues' function and lipid content are vital factors affecting the distribution of BTBPE and TBECH. Stereoselective accumulation of TBECH enantiomers was observed in zebrafish tissues, with first-eluting enantiomers, i.e. E1-α-TBECH and E1-ß-TBECH, preferentially accumulated. Additionally, the transformation products (TPs) in the zebrafish liver were comprehensively screened and identified using high-resolution mass spectrometry. Twelve TPs of BTBPE and eight TPs of TBECH were identified: biotransformation pathways involving ether cleavage, debromination, hydroxylation, and methoxylation reactions for BTBPE and hydroxylation, debromination, and oxidation processes for TBECH. Biotransformation is also a vital factor affecting the bioaccumulation potential of these two NBFRs, and the environmental impacts of NBFR TPs should be further investigated in future studies. The findings of this study provide a scientific basis for an accurate assessment of the ecological and environmental risks of BTBPE and TBECH.


Assuntos
Retardadores de Chama , Peixe-Zebra , Animais , Peixe-Zebra/metabolismo , Bioacumulação , Estereoisomerismo , Biotransformação , Cicloexanos/metabolismo , Retardadores de Chama/análise
6.
Nat Commun ; 15(1): 679, 2024 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-38263179

RESUMO

Tetrodotoxin and congeners are specific voltage-gated sodium channel blockers that exhibit remarkable anesthetic and analgesic effects. Here, we present a scalable asymmetric syntheses of Tetrodotoxin and 9-epiTetrodotoxin from the abundant chemical feedstock furfuryl alcohol. The optically pure cyclohexane skeleton is assembled via a stereoselective Diels-Alder reaction. The dense heteroatom substituents are established sequentially by a series of functional group interconversions on highly oxygenated cyclohexane frameworks, including a chemoselective cyclic anhydride opening, and a decarboxylative hydroxylation. An innovative SmI2-mediated concurrent fragmentation, an oxo-bridge ring opening and ester reduction followed by an Upjohn dihydroxylation deliver the highly oxidized skeleton. Ruthenium-catalyzed oxidative alkyne cleavage and formation of the hemiaminal and orthoester under acidic conditions enable the rapid assembly of Tetrodotoxin, anhydro-Tetrodotoxin, 9-epiTetrodotoxin, and 9-epi lactone-Tetrodotoxin.


Assuntos
Cicloexanos , Estresse Oxidativo , Tetrodotoxina , Hidroxilação , Compostos Radiofarmacêuticos
7.
J Environ Manage ; 353: 120132, 2024 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-38286067

RESUMO

The removal of volatile organic compounds (VOCs) in air is of utmost importance to safeguard both environmental quality and human well-being. However, the low aqueous solubility of hydrophobic VOCs results in poor removal in waste gas biofilters (BFs). In this study, we evaluated the addition of (bio)surfactants in three BFs (BF1 and BF2 mixture of compost and wood chips (C + WC), and BF3 filled with expanded perlite) to enhance the removal of cyclohexane and hexane from a polluted gas stream. Experiments were carried out to select two (bio)surfactants (i.e., Tween 80 and saponin) out of five (sodium dodecyl sulfate (SDS), Tween 80, surfactin, rhamnolipid and saponin) from a physical-chemical (i.e., decreasing VOC gas-liquid partitioning) and biological (i.e., the ability of the microbial consortium to grow on the (bio)surfactants) point of view. The results show that adding Tween 80 at 1 critical micelle concentration (CMC) had a slight positive effect on the removal of both VOCs, in BF1 (e.g., 7.0 ± 0.6 g cyclohexane m-3 h-1, 85 ± 2% at 163 s; compared to 6.7 ± 0.4 g cyclohexane m-3 h-1, 76 ± 2% at 163 s and 0 CMC) and BF2 (e.g., 4.3 ± 0.4 g hexane m-3 h-1, 27 ± 2% at 82 s; compared to 3.1 ± 0.7 g hexane m-3 h-1, 16 ± 4% at 82 s and 0 CMC), but a negative effect in BF3 at either 1, 3 and 9 CMC (e.g., 2.4 ± 0.4 g hexane m-3 h-1, 30 ± 4% at 163 s and 1 CMC; compared to 4.6 ± 1.0 g hexane m-3 h-1, 43 ± 8% at 163 s and 0 CMC). In contrast, the performance of all BFs improved with the addition of saponin, particularly at 3 CMC. Notably, in BF3, the elimination capacity (EC) and removal efficiency (RE) doubled for both VOCs (i.e., 9.1 ± 0.6 g cyclohexane m-3 h-1, 49 ± 3%; 4.3 ± 0.3 g hexane m-3 h-1, 25 ± 3%) compared to no biosurfactant addition (i.e., 4.5 ± 0.4 g cyclohexane m-3 h-1, 23 ± 3%; hexane 2.2 ± 0.5 g m-3 h-1, 10 ± 2%) at 82 s. Moreover, the addition of the (bio)surfactants led to a shift in the microbial consortia, with a different response in BF1-BF2 compared to BF3. This study evaluates for the first time the use of saponin in BFs, it demonstrates that cyclohexane and hexane RE can be improved by (bio)surfactant addition, and it provides recommendations for future studies in this field.


Assuntos
Saponinas , Compostos Orgânicos Voláteis , Humanos , Tensoativos/química , Hexanos , Polissorbatos , Cicloexanos , Filtração/métodos
8.
J Biomol Struct Dyn ; 42(4): 1765-1777, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-37097971

RESUMO

Depressive disorders are among most common psychiatric diseases and second most common form of psychiatric illness globally. Commonly available chemical drugs used for treatment of nervous system disorders exert undesirable effects. Therefore, there is a growing need towards exploring novel antidepressants of herbal origin. Earlier, the antidepressant effect of methanolic extract of garlic has been shown. In this study, the ethanolic extract of garlic was prepared and chemically analysed using Gas Chromatography - Mass Spectrometry (GC-MS) screening. A total of 35 compounds were found to be present, which might act as antidepressant. Using computational analyses, these compounds were screened as potential inhibitors (selective serotonin reuptake inhibitor (SSRI)) against serotonin transporter (SERT)/leucine receptor (LEUT). In silico docking studies and other physicochemical, bioactivity and ADMET studies resulted in the selection of compound 1 ((2-Cyclohexyl-1-methylpropyl) cyclohexane) as potential SSRI (binding energy -8.1 kcal/mol) compared to known reference SSRI fluoxetine (binding energy -8.0 kcal/mol). Analysis of conformational stability, residue flexibility, compactness, binding interactions, solvent accessible surface area (SASA), dynamic correlation, and binding free energy predicted from molecular mechanics (MD) with generalised Born and surface area solvation (MM/GBSA) studies revealed formation of a more stable SSRI like complex with compound 1 having strong inhibitory interaction compared to known SSRI fluoxetine/reference complex. Thus, compound 1 may act as an active SSRI leading to discovery of potential antidepressant drug.Communicated by Ramaswamy H. Sarma.


Assuntos
Fluoxetina , Alho , Fluoxetina/farmacologia , Simulação de Dinâmica Molecular , Antidepressivos/farmacologia , Inibidores Seletivos de Recaptação de Serotonina/farmacologia , Cicloexanos , Simulação de Acoplamento Molecular
9.
Environ Toxicol ; 39(3): 1245-1257, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37927243

RESUMO

Diisononyl phthalate (DINP) and di(isononyl)cyclohexane-1,2-dicarboxylate (DINCH) are plasticizers introduced to replace previously used phthalate plasticizers in polymeric products. Exposure to DINP and DINCH has been shown to impact lipid metabolism. However, there are limited studies that address the mechanisms of toxicity of these two plasticizers. Here, a comparative toxicity analysis has been performed to evaluate the impacts of DINP and DINCH on 3T3-L1 cells. The preadipocyte 3T3-L1 cells were exposed to 1, 10, and 100 µM of DINP or DINCH for 10 days and assessed for lipid accumulation, gene expression, and protein analysis. Lipid staining showed that higher concentrations of DINP and DINCH can induce adipogenesis. The gene expression analysis demonstrated that both DINP and DINCH could alter the expression of lipid-related genes involved in adipogenesis. DINP and DINCH upregulated Pparγ, Pparα, C/EBPα Fabp4, and Fabp5, while both compounds significantly downregulated Fasn and Gata2. Protein analysis showed that both DINP and DINCH repressed the expression of FASN. Additionally, we analyzed an independent transcriptome dataset encompassing temporal data on lipid differentiation within 3T3-L1 cells. Subsequently, we derived a gene set that accurately portrays significant pathways involved in lipid differentiation, which we subsequently subjected to experimental validation through quantitative polymerase chain reaction. In addition, we extended our analysis to encompass a thorough assessment of the expression profiles of this identical gene set across 40 discrete transcriptome datasets that have linked to diverse pathological conditions to foreseen any potential association with DINP and DINCH exposure. Comparative analysis indicated that DINP could be more effective in regulating lipid metabolism.


Assuntos
Ácidos Cicloexanocarboxílicos , Ácidos Ftálicos , Animais , Camundongos , Plastificantes/toxicidade , Metabolismo dos Lipídeos , Células 3T3-L1 , Ácidos Cicloexanocarboxílicos/toxicidade , Ácidos Dicarboxílicos/toxicidade , Ácidos Ftálicos/toxicidade , Cicloexanos , Lipídeos
10.
Int J Environ Health Res ; 34(2): 968-978, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36966491

RESUMO

Detection of pesticide residues in soil samples was conducted using UHPLC-MS/MS. Non-dietary health risk assessment was conducted using calculate chronic daily intake (CDI) from ingestion, inhalation and dermal contact pathways and following non-carcinogenic and carcinogenic risks in the adults and adolescent. The rank order of pesticide in soil based on their concentration was malathion (0.082 mg kg-1)> cyproconazole (0.019 mg kg-1)> propargite (0.018 mg kg-1)> butachlor (0.016 mg kg-1) > chlorpyrifos (0.0067 mg kg-1)> diazinon (0.0014 mg kg-1)> imidacloprid (0.0007 mg kg-1). Hazard index (HI) values obtained of exposure to pesticides in soil in adults and adolescent were 0.0012 and 0.0035, respectively. Hence, exposed population are at the acceptable range of non-carcinogenic risk (HI < 1). Cancer risk (CR) values due to propargite in soil via ingestion pathway in adults and adolescent were 2.03E-09 and 2.08E-09, respectively; therefore, carcinogenic risk due to the exposure to pesticide contaminated soil was safe range (CR < 1E-06).


Assuntos
Cicloexanos , Resíduos de Praguicidas , Praguicidas , Poluentes do Solo , Adulto , Adolescente , Humanos , Resíduos de Praguicidas/toxicidade , Resíduos de Praguicidas/análise , Solo/química , Fazendas , Irã (Geográfico) , Espectrometria de Massas em Tandem , Poluentes do Solo/toxicidade , Poluentes do Solo/análise , Praguicidas/toxicidade , Medição de Risco , Carcinógenos/análise
11.
J Environ Manage ; 351: 119795, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38091735

RESUMO

A carbon trading market (CTM) policy for trading carbon dioxide emission rights as a commodity was created to reduce greenhouse gas emissions. CTMs operate differently in different countries and regions, and their interactions deserve an in-depth study. This study focused on the world's largest CTM, the European Union (EU), and the CTM of China, largest carbon-emitting country. First, we evaluate the liquidity and volatility of the two CTMs. Subsequently, the VAR model is used to explore the mean spillover effect between the two markets and the BEKK-GARCH model is used to explore the volatility spillover effect between the two markets. The study concludes that: (1) The liquidity of China's CTM is better than that of the EU's CTM. (2) Both the EU and Chinese CTMs are unstable, but the volatility of the Chinese CTM is lower than that of the EU CTM. (3) Price changes in the EU and Hubei CTMs have a mutual influence. (4) There are interactions between the market fluctuations of the EU CTM and the Shanghai CTM and those of the EU CTM and the Hubei CTM. The results of this study have implications for the construction and development of CTMs in the EU and China.


Assuntos
Cicloexanos , Mesilatos , China , União Europeia
12.
Chemosphere ; 349: 140900, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38065261

RESUMO

Management of growing volumes of fluid fine tailings (FFT) is a significant challenge for oil sands industry. A potential alternative non-aqueous solvent extraction (NAE) process uses cycloalkane solvent such as cyclohexane or cyclopentane with very little water and generates smaller volumes of 'dry' solids (NAES) with residual solvent. Here we investigate remediation of NAES in a simulated bench-scale upland reclamation scenario. In the first study, microcosms with nutrient medium plus FFT as inoculum were amended with cyclohexane and incubated for ∼1 year, monitoring for cyclohexane biodegradation under aerobic conditions. Biodegradation of cyclohexane occurred under aerobic conditions with no metabolic intermediates detected. A second study using NAES mixed with FFT spiked with cyclohexane and cyclopentane, with or without additional nutrients (nitrogen and phosphorus), showed complete and rapid aerobic biodegradation of both cycloalkanes in NAES inoculated with FFT and supplemented with nutrients. 16S rRNA gene sequencing revealed dominance of Rhodoferax and members of Burkholderiaceae during aerobic cyclohexane biodegradation in FFT, and Hydrogenophaga, Acidovorax, Defluviimonas and members of Porticoccaceae during aerobic biodegradation of cyclohexane and cyclopentane in NAES inoculated with FFT and supplemented with nutrients. The findings indicate that biodegradation of cycloalkanes from NAES is possible under aerobic condition, which will contribute to the successful reclamation of oil sands tailings for land closure.


Assuntos
Cicloparafinas , Campos de Petróleo e Gás , RNA Ribossômico 16S , Cicloexanos , Ciclopentanos , Biodegradação Ambiental , Solventes
13.
Environ Pollut ; 343: 123183, 2024 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-38110047

RESUMO

With the gradual deepening of the research and governance of air pollution, chemical transport models (CTMs), especially the third-generation CTMs based on the "1 atm" theory, have been recognized as important tools for atmospheric environment research and air quality management. In this review article, we screened 2396 peer-reviewed manuscripts on the application of four pre-selected regional CTMs in the past five years. CAMx, CMAQ, WRF-Chem and NAQPMS models are well used in the simulation of atmospheric pollutants. In the simulation study of secondary pollutants such as O3, secondary organic aerosol (SOA), sulfates, nitrates, and ammonium (SNA), the CMAQ model has been widely applied. Secondly, model evaluation indicators are diverse, and the establishment of evaluation criteria has gone through the long-term efforts of predecessors. However, the model performance evaluation system still needs further specification. Furthermore, temporal-spatial resolution, emission inventory, meteorological field and atmospheric chemical mechanism are the main sources of uncertainty, and have certain interference with the simulation results. Among them, the inventory and mechanism are particularly important, and are also the top priorities in future simulation research.


Assuntos
Poluentes Atmosféricos , Poluição do Ar , Cicloexanos , Mesilatos , Poluentes Atmosféricos/análise , Material Particulado/análise , Incerteza , Poluição do Ar/análise , Monitoramento Ambiental/métodos
15.
PLoS One ; 18(12): e0284887, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38064437

RESUMO

Sex hormones exert a wide influence on several systems of the human body, especially in women, who undergo intense changes in the trans and postmenopausal periods. Different experimental models are used to mimic these conditions; however, the impact on hormonal profile may be different. This study aimed to analyze and compare vaginal cytology of different post-estropausal mice models, along with their microscopical ovarian features. Forty-six C57BL/6J female mice with the ages of 4, 6 and 18 months at the beginning of the experiment, weighing about 25-28 grams, constituted five groups: NC-(negative control) animals with no treatment, OVX-SHAM-sham ovariectomized, OVX-ovariectomized, VCD-medicated with 160 mg/kg/day of 4-vinylcyclohexene diepoxide via IP for 20 consecutive days, and Aged-senescent mice under physiological estropause. Euthanasia was performed at different periods for the removal of the ovaries, and after diestrus was confirmed by vaginal cytology for 10 consecutive days. For daily vaginal cytology, morphological and histomorphometric microscopic analyzes were performed. Aged mice presented significant increased neutrophils when compared to VCD group, as well as increased cornified epithelial cells when compared to OVX mice, and also increased nucleated epithelial cells when compared to VCD and OVX. NC and OVX-SHAM ovaries presented innumerous follicles at different stages of development, while VCD showed marked follicular atresia, depleted of primordial or developing follicles and a predominance of interstitial cells. The ovaries of aged mice were predominantly constituted by corpus luteum degenerated into corpus albicans, with rare antral follicles. All analyzed models led to different permanent diestrus profiles caused by each model, as indicated by ovarian features. This should be carefully considered when choosing a post-estropausal experimental model, in order to better correlate this challenging phase of female's life with physiological/pathological conditions.


Assuntos
Menopausa Precoce , Insuficiência Ovariana Primária , Humanos , Feminino , Camundongos , Animais , Idoso , Insuficiência Ovariana Primária/induzido quimicamente , Cicloexanos , Diestro , Camundongos Endogâmicos C57BL , Atresia Folicular , Cicloexenos , Modelos Animais de Doenças , Compostos de Vinila
16.
IEEE Trans Biomed Eng ; 70(9): 2564-2572, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-37656637

RESUMO

BACKGROUND: Neurons demonstrate very distinct nonlinear activation dynamics, influenced by the neuron type, morphology, ion channel expression, and various other factors. The measurement of the activation dynamics can identify the neural target of stimulation and detect deviations, e.g., for diagnosis. This paper describes a tool for closed-loop sequential parameter estimation (SPE) of the activation dynamics through transcranial magnetic stimulation (TMS). The proposed SPE method operates in real time, selects ideal stimulus parameters, detects and processes the response, and concurrently estimates the input-output (IO) curve and the first-order approximation of the activated neural target. OBJECTIVE: To develop a method for concurrent SPE of the first-order activation dynamics and IO curve with closed-loop TMS. METHOD: First, identifiability of an integrated model of the first-order neural activation dynamics and IO curve is assessed, demonstrating that at least two IO curves need to be acquired with different pulse widths. Then, a two-stage SPE method is proposed. It estimates the IO curve by using Fisher information matrix (FIM) optimization in the first stage and subsequently estimates the membrane time constant as well as the coupling gain in the second stage. The procedure continues in a sequential manner until a stopping rule is satisfied. RESULTS: The results of 73 simulation cases confirm the satisfactory estimation of the membrane time constant and coupling gain with average absolute relative errors (AREs) of 6.2% and 5.3%, respectively, with an average of 344 pulses (172 pulses for each IO curve or pulse width). The method estimates the IO curves' lower and upper plateaus, mid-point, and slope with average AREs of 0.2%, 0.7%, 0.9%, and 14.5%, respectively. The conventional time constant estimation method based on the strength-duration (S-D) curve leads to 33.3% ARE, which is 27.0% larger than 6.2% ARE obtained through the proposed real-time FIM-based SPE method in this paper. CONCLUSIONS: SPE of the activation dynamics requires acquiring at least two IO curves with different pulse widths, which needs a controllable TMS (cTMS) device with adjustable pulse duration. SIGNIFICANCE: The proposed SPE method enhances the cTMS functionality, which can contribute novel insights in research and clinical studies.


Assuntos
Encéfalo , Estimulação Magnética Transcraniana , Cicloexanos , Mesilatos
17.
Sci Total Environ ; 904: 167326, 2023 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-37748600

RESUMO

The emission of volatile organic compounds (VOCs) into the atmosphere causes negative environmental and health effects. Biofiltration is known to be an efficient and cost-effective treatment technology for the removal of VOCs in waste gas streams. However, little is known on the removal of VOC mixtures and the effect of operational conditions, particularly for hydrophobic VOCs, and on the microbial populations governing the biofiltration process. In this study, we evaluated the effect of inoculum type (acclimated activated sludge (A-AS) versus Rhodococcus erythropolis) and packing material (mixture of compost and wood chips (C + WC) versus expanded perlite) on the removal of a mixture of hydrophobic VOCs (toluene, cyclohexane and hexane) in three biofilters (BFs), i.e., BF1: C + WC and R. erythropolis; BF2: C + WC and A-AS; and BF3: expanded perlite and R. erythropolis. The BFs were operated for 374 days at varying inlet loads (ILs) and empty bed residence times (EBRTs). The results showed that the VOCs were removed in the following order: toluene > cyclohexane > hexane, which corresponds to their air-water partitioning coefficient and thus bioavailability of each VOC. Toluene is the most hydrophilic VOC, while hexane is the most hydrophobic. BF2 outperformed BF1 and BF3 in each operational phase, with average maximum elimination capacities (ECmax) of 21 ± 3 g toluene m-3 h-1 (removal efficiency (RE): 100 %; EBRT: 82 s), 11 ± 2 g cyclohexane m-3 h-1 (RE: 86 ± 6 %; EBRT: 163 s) and 6.2 ± 0.9 g hexane m-3 h-1 (RE: 96 ± 4 %; EBRT: 245 s). Microbial analysis showed that despite having different inocula, the genera Rhodococcus, Mycobacterium and/or Pseudonocardia dominated in all BFs but at different relative abundances. This study provides new insights into the removal of difficult-to-degrade VOC mixtures with limited research to date on biofiltration.


Assuntos
Poluentes Atmosféricos , Compostos Orgânicos Voláteis , Compostos Orgânicos Voláteis/análise , Filtração/métodos , Hexanos , Biodegradação Ambiental , Cicloexanos , Tolueno , Poluentes Atmosféricos/análise , Reatores Biológicos/microbiologia
18.
Environ Sci Pollut Res Int ; 30(41): 94740-94756, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37540420

RESUMO

The cyclohexane is the common toxic volatiles emitted from the various industry in worldwide leading to environmental degradation and human illnesses. Hence, there is a requirement for an efficient and stable adsorbent for adsorbing these toxic molecules to safeguard human health and the air atmosphere. Hollow carbon spheres (HCS) are a new type of carbon nanomaterial with large specific surface area, low density, and good chemical and thermal stability. In this study, DFT simulations and static-dynamic adsorption studies of cyclohexane were carried out using HCS as the adsorbent material. Among them, static adsorption focuses on adsorption/desorption isotherm, adsorption isotherm model fitting and isosteric heat of adsorption. Dynamic adsorption was mainly studied the effect of initial concentrations, gas flow rate, and ambient temperature on adsorption performance. The results showed that HCS exhibited very good performance in cyclohexane adsorption.


Assuntos
Carbono , Simulação por Computador , Cicloexanos , Adsorção , Carbono/química , Cicloexanos/química , Termodinâmica , Microesferas , Dióxido de Silício/química
19.
AIDS ; 37(13): 1987-1995, 2023 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-37418541

RESUMO

OBJECTIVES: Chemokine receptor CCR5 is the principal co-receptor for entry of M-tropic HIV virus into immune cells. It is expressed in the central nervous system and may contribute to neuro-inflammation. The CCR5 antagonist maraviroc (MVC) has been suggested to improve HIV-associated neurocognitive impairment (NCI). DESIGN: A double-blind, placebo-controlled, 48-week, randomized study of MVC vs. placebo in people with HIV (PWH) on stable antiretroviral therapy (ART) for more than one year in Hawaii and Puerto Rico with plasma HIV RNA less than 50 copies/ml and at least mild NCI defined as an overall or domain-specific neuropsychological z (NPZ) score less than -0.5. METHODS: Study participants were randomized 2 : 1 to intensification of ART with MVC vs. placebo. The primary endpoint was change in global and domain-specific NPZ modeled from study entry to week 48. Covariate adjusted treatment comparisons of average changes in cognitive outcome were performed using winsorized NPZ data. Monocyte subset frequencies and chemokine expression as well as plasma biomarker levels were assessed. RESULTS: Forty-nine participants were enrolled with 32 individuals randomized to MVC intensification and 17 to placebo. At baseline, worse NPZ scores were seen in the MVC arm. Comparison of 48-week NPZ change by arm revealed no differences except for a modest improvement in the Learning and Memory domain in the MVC arm, which did not survive multiplicity correction. No significant changes between arms were seen in immunologic parameters. CONCLUSION: This randomized controlled study found no definitive evidence in favor of MVC intensification among PWH with mild cognitive difficulties.


Assuntos
Infecções por HIV , Humanos , Maraviroc , Infecções por HIV/complicações , Infecções por HIV/tratamento farmacológico , Cicloexanos , Triazóis/uso terapêutico , Terapia Antirretroviral de Alta Atividade
20.
J Org Chem ; 88(13): 7918-7928, 2023 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-37279190

RESUMO

An efficient cascade protocol for the stereoselective synthesis of borylated carbocycles via copper-catalyzed borylative Michael/Michael cyclization is presented. Using this mild approach, up to 24 new boronic ester substituted indanes, cyclohexanes, and cyclopentanes were prepared in good yields with excellent diasteroselectivities and exceptional functional group tolerance. Furthermore, carbacyclic boronates were oxidized successfully through synthetic transformation. Gram-scale synthesis of the present protocol was also carried out effectively.


Assuntos
Cicloexanos , Ciclopentanos , Estrutura Molecular , Estereoisomerismo , Ciclização
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