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1.
Water Sci Technol ; 82(7): 1285-1295, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33079709

RESUMO

Microbial fuel cells were developed using two different water sources: (1) unpolluted water (Kala Talao Lake) and (2) polluted water (Waldhuni River). The maximum output voltage provided by each source was compared, as was the cell voltage variation with anode porosity. The variation in power density of each cell with variation in anode porosity was also studied. The analysis of the MFCs' internal resistance (Rin) was also conducted and the variation with increased anode porosity was identified. The pH variation in both the MFCs is also reported. The cells' higher voltage output resulting in a lower pH was confirmed and variation of the pH gradient with increased porosity of anode was recorded. An analysis of the chemical oxygen demand (COD) values and water conductivity of the MFCs was also carried out. A significant drop in the COD values with increasing anode porosity occurred in both cells. The finding of increased porosity was also studied with decreased conductivity. In addition, variations in chloride content and total dissolved salts with porosity were performed.


Assuntos
Fontes de Energia Bioelétrica , Análise da Demanda Biológica de Oxigênio , Eletrodos , Porosidade
2.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 2299-2302, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018467

RESUMO

The fluid dynamics of microporous materials are important to many biomedical processes such as cell deposition in scaffold materials, tissue engineering, and bioreactors. Microporous scaffolds are frequently composed of suspensions of beads that have varying topology which, in turn, informs their hydrodynamic properties. Previous work has shown that shear stress distributions can affect the response of cells in microporous environments. Using computational fluid dynamics, we characterize localized differences in fluid flow attributes such wall shear stress and velocity to better understand the fluid dynamics underpinning microporous device function. We evaluated whether bead packings with similar void fractions had different fluid dynamics as characterized by the distribution of velocity magnitudes and wall shear stress and found that there are differences despite the similarities in void fraction. We show that another metric, the average distance to the nearest wall, can provide an additional variable to measure the porosity and susceptibility of microporous materials to high shear stress. By increasing our understanding of the impact of bead size on cell scaffold fluid dynamics we aim to increase the ability to predict important attributes such as loading efficiency in these devices.


Assuntos
Hidrodinâmica , Tecidos Suporte , Porosidade , Estresse Mecânico , Engenharia Tecidual
3.
PLoS One ; 15(8): e0238319, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32866174

RESUMO

Wood is a porous, hygroscopic material with engineering properties that depend significantly on the amount of water (moisture) in the material. Water in wood can be present in both cell walls and the porous void-structure of the material, but it is only water in cell walls that affects the engineering properties. An important characteristic of wood is therefore the capacity for water of its solid cell walls, i.e. the maximum cell wall moisture content. However, this quantity is not straight-forward to determine experimentally, and the measured value may depend on the experimental technique used. In this study, we used a triangulation approach to determine the maximum cell wall moisture content by using three experimental techniques based on different measurement principles: low-field nuclear magnetic resonance (LFNMR) relaxometry, differential scanning calorimetry (DSC), and the solute exclusion technique (SET). The LFNMR data were furthermore analysed by two varieties of exponential decay analysis. These techniques were used to determine the maximum cell wall moisture contents of nine different wood species, covering a wide range of densities. The results from statistical analysis showed that LFNMR yielded lower cell wall moisture contents than DSC and SET, which were fairly similar. Both of the latter methods include factors that could either under-estimate or over-estimate the measured cell wall moisture content. Because of this and the fact that the DSC and SET methods are based on different measurement principles, it is likely that they provide realistic values of the cell wall moisture content in the water-saturated state.


Assuntos
Parede Celular/metabolismo , Água/metabolismo , Madeira/metabolismo , Porosidade
4.
Nat Commun ; 11(1): 4772, 2020 09 24.
Artigo em Inglês | MEDLINE | ID: mdl-32973145

RESUMO

Surface-enhanced Raman spectroscopy (SERS) is a powerful tool for vibrational spectroscopy as it provides several orders of magnitude higher sensitivity than inherently weak spontaneous Raman scattering by exciting localized surface plasmon resonance (LSPR) on metal substrates. However, SERS can be unreliable for biomedical use since it sacrifices reproducibility, uniformity, biocompatibility, and durability due to its strong dependence on "hot spots", large photothermal heat generation, and easy oxidization. Here, we demonstrate the design, fabrication, and use of a metal-free (i.e., LSPR-free), topologically tailored nanostructure composed of porous carbon nanowires in an array as a SERS substrate to overcome all these problems. Specifically, it offers not only high signal enhancement (~106) due to its strong broadband charge-transfer resonance, but also extraordinarily high reproducibility due to the absence of hot spots, high durability due to no oxidization, and high compatibility to biomolecules due to its fluorescence quenching capability.


Assuntos
Carbono/química , Nanofios/química , Análise Espectral Raman/métodos , Fluorescência , Porosidade , Reprodutibilidade dos Testes , Ressonância de Plasmônio de Superfície/métodos , Propriedades de Superfície
5.
PLoS One ; 15(8): e0237271, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32866161

RESUMO

Molecular separation of pharmaceutical contaminants from water has been recently of great interest to alleviate their detrimental impacts on environment and human well-being. As the novelty, this investigation aims to develop a mechanistic modeling approach and consequently its related CFD-based simulations to evaluate the molecular separation efficiency of ibuprofen (IP) and its metabolite 4-isobutylacetophenone (4-IBAP) from water inside a porous membrane contactor (PMC). For this purpose, octanol has been applied as an organic phase to extract IP and 4-IBAP from the aqueous solution due to high solubility of solutes in octanol. Finite element (FE) technique is used as a promising tool to simultaneously solve continuity and Navier-Stokes equations and their associated boundary conditions in tube, shell and porous membrane compartments of the PMC. The results demonstrated that the application of PMC and liquid-liquid extraction process can be significantly effective due to separating 51 and 54% of inlet IP and 4-IBAP molecules from aqueous solution, respectively. Moreover, the impact of various operational / functional parameters such as packing density, the number of fibrous membrane, the module length, the membrane porosity / tortuosity, and ultimately the aqueous solution flow rate on the molecular separation efficiency of IP and 4-IBAP is studied in more details.


Assuntos
Acetofenonas/isolamento & purificação , Anti-Inflamatórios não Esteroides/isolamento & purificação , Ibuprofeno/isolamento & purificação , Membranas Artificiais , Polímeros/química , Extração Líquido-Líquido/métodos , Octanóis/química , Porosidade , Solubilidade , Soluções
6.
Zhongguo Gu Shang ; 33(8): 784-7, 2020 Aug 25.
Artigo em Chinês | MEDLINE | ID: mdl-32875773

RESUMO

As a new potential bone graft material, tissue engineered bone effectively compensates for the defects of today's bone repair materials. Meanwhile, mesoporous silica nanomaterials(MSNs) have been widely recognized due to their large specific surface area, good biocompatibility, and capability of further processing and modification. They have promising application prospects in bone tissue engineering. For the basic scientific research results that have been carried out in the early stage, the basic characteristics of mesoporous silica nano biomaterials and their application advantages, research status and development prospects in bone tissue engineering are reviewed. As for the research status, there are two aspects--as a carrier or as a component of engineering scaffolds. For the first aspect, different kinds of loaded drugs and different loading methods are reviewed. For the second, microstructure and mechanical properties of various complex scaffolds containing MSNs and the molecular and cellular behavior of seeded cells on these scaffolds are reviewed. The research of MSNs in bone cements and metal ions doped MSNs in bone tissue engineering are also included. The future development of MSNs in bone tissue engineering is also discussed.


Assuntos
Nanopartículas , Dióxido de Silício , Osso e Ossos , Porosidade , Engenharia Tecidual
7.
Int J Oral Implantol (Berl) ; 13(3): 241-252, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32879929

RESUMO

PURPOSE: Implant primary stability has long been considered a prerequisite for successful osseointegration. However, achieving stability may be difficult when placing implants in wide postextractive bone defects. The purpose of this study was to conduct a clinical and radiographic investigation of bone modifications at porous-structured implants inserted with or without primary stability. MATERIALS AND METHODS: Fifty porous-structured implants were inserted in the posterior sockets of 50 consecutive patients 2 months after tooth extraction, combined with allogeneic bone and a resorbable membrane. The implants were divided into two groups according to insertion torque: spinner (spinning at 35 Ncm, n = 23) and stable (stable at 35 Ncm, n = 27). Implant stability was assessed by resonance frequency analysis from baseline to 6-month function. Follow-up took place 3 years after implant placement. RESULTS: At baseline, the implant stability quotient was undetectable in the spinner group and averaged 75.07 ± 5.84 in the stable group. At uncovering, the implant stability quotient increased to 71.33 ± 4.42 and 77.97 ± 3.30 in the spinner and stable group, respectively (P < 0.001). After 6 months of loading, no between-group difference in implant stability quotient was found (P = 0.13). Marginal bone level changes were similar between groups at all follow-ups, averaging -0.41 ± 0.77 mm and -0.15 ± 0.53 mm at 36-month follow-up in the spinner and stable group, respectively (P = 0.35). No implant failed throughout the observation period. Neither biological nor mechanical complications occurred. CONCLUSION: Implants with a moderately rough surface and a porous-structured body may osseointegrate even without primary stability.


Assuntos
Implantes Dentários para Um Único Dente , Implantes Dentários , Implantação Dentária Endo-Óssea , Estética Dentária , Humanos , Porosidade , Alvéolo Dental/cirurgia
8.
Braz Dent J ; 31(4): 385-391, 2020 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-32901714

RESUMO

The present study evaluated the odontogenic potential of human dental pulp cells (HDPCs) exposed to chitosan scaffolds containing calcium aluminate (CHAlCa) associated or not with low doses of simvastatin (SV). Chitosan scaffolds received a suspension of calcium aluminate (AlCa) and were then immersed into solutions containing SV. The following groups were established: chitosan-calcium-aluminate scaffolds (CHAlCa - Control), chitosan calcium-aluminate with 0.5 µM SV (CHAlCa-SV0.5), and chitosan calcium-aluminate with 1.0 µM SV (CHAlCa-SV1.0). The morphology and composition of the scaffolds were evaluated by SEM and EDS, respectively. After 14 days of HDPCs culture on scaffolds, cell viability, adhesion and spread, mineralized matrix deposition as well as gene expression of odontogenic markers were assessed. Calcium aluminate particles were incorporated into the chitosan matrix, which exhibited regular pores homogeneously distributed throughout its structure. The selected SV dosages were biocompatible with HDPCs. Chitosan-calcium-aluminate scaffolds with 1 µM SV induced the odontoblastic phenotype in the HDPCs, which showed enhanced mineralized matrix deposition and up-regulated ALP, Col1A1, and DMP-1 expression. Therefore, one can conclude that the incorporation of calcium aluminate and simvastatin in chitosan scaffolds had a synergistic effect on HDPCs, favoring odontogenic cell differentiation and mineralized matrix deposition.


Assuntos
Quitosana , Compostos de Alumínio , Cálcio , Compostos de Cálcio , Humanos , Porosidade , Sinvastatina
9.
Artigo em Inglês | MEDLINE | ID: mdl-32926007

RESUMO

The aim of this study was to compare the effect of an autogenous blood concentrate (L-PRF) with the effect of white porous titanium granules (WPTG) on buccal bone remodeling. These materials were used to graft the void between the implant and the buccal bone following immediate implant placement. Clinical measurements were made at two time points, and the mean buccal bone horizontal dimension at placement was 2.94 ± 0.59 mm for L-PRF and 3.49 ± 0.99 mm for WPTG. At reentry, the values were 1.19 ± 0.90 mm and 2.12 ± 0.87 mm, respectively. Overall, there was no difference observed in the performance of the two materials regarding buccal bone resorption.


Assuntos
Implantes Dentários , Fibrina Rica em Plaquetas , Placas Ósseas , Porosidade , Estudos Prospectivos , Titânio , Alvéolo Dental
10.
PLoS One ; 15(9): e0238469, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32877469

RESUMO

The spatial arrangement and pore size distribution play an important role in accumulation and protection of exogenous organic matter (EOM) in the soil, but how different organic materials contribute to modify pore structure is poorly understood. We aimed at exploring possible changes in the complexity of the soil phase during fertilization with different doses of digestate and sludges sourced from the agro-food industry. For this purpose, the short-term effects-one year, of soil fertilization, were investigated in several sampling periods and within two depths (0-25 cm and 25-40 cm). Changes in the specific surface area (SSA), total pore volume (VMIP), total pore area (SMIP), average pore radius (RMIP) and pore size distribution (PSD) were monitored using N2 adsorption/desorption (NAD) and mercury porosimetry (MIP) methods. Our results showed that the intensity of observed changes depended on the type and dose of organic material, soil depth and sampling date. Accumulation of EOM increased with soil depth, masking a large proportion of SSA. Deeper soil layer was more susceptible to changes in the pore size distributions due to the formation of new elongated pores. We concluded that this specific structural porosity was related to the decomposition of organic matter during the formation of soil aggregates.


Assuntos
Agricultura/métodos , Fertilizantes/análise , Solo/química , Adsorção , Indústria Alimentícia , Mercúrio/química , Nitrogênio/química , Porosidade , Esgotos/química
11.
PLoS One ; 15(9): e0229841, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32946470

RESUMO

Starch based gluten-free bread (formulations containing mixture of corn and potato starch with hydrocolloids) are deficient in nutrients and do not contain health promoting compounds. Therefore they could be supplemented with raw materials rich in such components, especially antioxidants. Among them pseudo-cereals, seeds, fruits and vegetables are often applied to this purpose. Potato pulp produced by processing red fleshed (Magenta Love) and purple fleshed (Violetta) varieties could become a new innovative substrate for gluten-free bread enrichment, because of high levels of endogenous polyphenols, namely flavonoids, flavonols, phenolic acids and especially anthocyanins with high antioxidant potential, as well as dietary fiber. Study material consisted of gluten-free bread enriched in the pulp. Dietary fiber, acrylamide content and antioxidant and antiradical potential of the bread were determined. Sensory evaluation included crumb elasticity, porosity and other characteristics, taste and smell. Among all analyzed gluten-free breads, the sample containing 7.5% share of freeze-dried red potato pulp Magenta Love was characterized by high content of phenolic compounds and dietary fiber, pronounced antioxidant activity, low levels of potentially dangerous acrylamide and good physical and sensory characteristics. Therefore such an addition (7.5% Magenta Love) could be recommended for industrial production of gluten-free bread.


Assuntos
Pão , Farinha/análise , Ingredientes de Alimentos/análise , Solanum tuberosum/química , Verduras/química , Acrilamida/análise , Antioxidantes/análise , Doença Celíaca/dietoterapia , Doença Celíaca/imunologia , Fibras na Dieta/análise , Liofilização/métodos , Glutens/imunologia , Humanos , Valor Nutritivo , Polifenóis/análise , Porosidade , Olfato , Amido/isolamento & purificação , Paladar
12.
J Biomed Nanotechnol ; 16(5): 652-658, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32919485

RESUMO

Fragrances are extensively applied in food, daily chemicals, tobacco and medicine industries. However, too strong volatility of fragrances results in a fast release rate, thereby reducing the usage time of aromatherapy products. Although loading fragrances into nanomaterials is capable of slowing their rates of release, the encapsulation efficiency of traditional nanomaterials is very low, and the nanomaterials themselves are not stable. Herein, hollow mesoporous silica nanoparticles (hMSNs) were designed for encapsulation of eugenol and the nano-fragrance was named EG@hMSNs. The structure of hMSNs was stable and the encapsulation rate of eugenol reached 46.5%. Besides, EG@hMSNs could significantly slow the release rate of eugenol. Subsequently, the EG@hMSNs were testified that they had positive roles in stress relief by open field tests. The molecular mechanisms of these positive effects on the central nervous system were then explored. Furthermore, the preparation method of hMSCs was simple, and the preparation cost was low. Therefore, EG@hMSNs are expected to be industrially produced and have a great application prospect.


Assuntos
Nanopartículas , Eugenol , Sistema Nervoso , Porosidade , Dióxido de Silício
13.
J Chromatogr A ; 1626: 461328, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797818

RESUMO

Ferric oxide/carbon (Fe2O3@C) was fabricated via direct carbonization of metal-organic framework of iron (MOF-235) under argon atmosphere. The magnetic Fe2O3 nanoparticles are evenly embedded in porous carbon matrix, while original morphology of MOF-235 was well-maintained. The synthesized Fe2O3@C was used as magnetic sorbent for extracting five benzoylurea insecticides (BUs). The materials exhibited excellent extraction performance, which benefited not only from the strong π-π interaction and hydrophobic interaction (π-conjugated system), but also to the abundant adsorption sites and flexible transport channel (the interconnected 3D porous structure). A three-factor-three-level Box-Behnken design (BBD) was selected to optimize three greatly influential parameters: amount of adsorbent (A), desorption time (B) and volume of desorption solvent (C) by response surface methodology. The established method coupled to HPLC-UV detection showed wide linearity with the range of 0.2-450 µg•L-1, relatively low limits of detection (0.05-0.10 µg•L-1) with the relative standard deviation (RSD) (n = 7) lower t than 5.47%. Moreover, the proposed method was successfully applied to analyze BUs in tea samples and investigate the removal effect of different washing on BUs residues from tea leaf. These results indicated that the synthesized Fe2O3@C is a promising adsorbent material for magnetic solid phase extraction of BUs at trace concentrations from tea samples.


Assuntos
Inseticidas/análise , Nanopartículas de Magnetita/química , Estruturas Metalorgânicas/química , Chá/química , Ureia/análise , Adsorção , Carbono/química , Cromatografia Líquida de Alta Pressão/métodos , Cromatografia Líquida de Alta Pressão/normas , Compostos Férricos/química , Inseticidas/isolamento & purificação , Inseticidas/normas , Limite de Detecção , Porosidade , Padrões de Referência , Extração em Fase Sólida , Espectrofotometria Ultravioleta , Chá/metabolismo , Ureia/análogos & derivados , Ureia/isolamento & purificação , Ureia/normas
14.
J Chromatogr A ; 1626: 461339, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797821

RESUMO

We report on a systematic and comprehensive (0.7 ≤ k'' ≤ 122) experimental study of the effect of the zone retention factor k'' on eddy dispersion (heddy) in packed bed columns for liquid chromatography. The values for heddy are obtained by subtracting rigorously estimated contributions to the total plate height from longitudinal diffusion (hB) and the mobile (hCm) and stationary zone (hCs) mass transfer resistances. For the first time, hCm-values are calculated using an expression for the Sherwood number (Sh) that has been established and validated in the relevant velocity range. Experiments were carried out on both a fully-porous and a core-shell particle column. In both cases, the eddy dispersion systematically decreased with increasing retention factor k'', dropping 0.5 to 0.8 reduced plate height units when going from the lowest to the highest k''. To establish a simple empirical fitting equation that can represent the observed effects, the widely used power law-based Knox model has been extended to express the dependence of its A- and n-parameters on the retention factor.


Assuntos
Cromatografia Líquida/métodos , Algoritmos , Cromatografia Líquida/instrumentação , Difusão , Tamanho da Partícula , Porosidade
15.
J Chromatogr A ; 1626: 461341, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797822

RESUMO

The recognition and separation of polar chiral compounds are important technological challenges in separation science. Taking full advantage of the intrinsically chiral environment and multiple interactions featured by macrocycles, we designed the first example of porous methylated cyclodextrins-containing polymers (MP-CDPs) with three-dimensional (3D) chiral channels. The enantioselective recognition of (R)/(S)-1-phenylethylamine mixtures was realized with enantiomer excess (e.e.) >73% in only 3 min by using MP-CDPs as the adsorbent. The obtained MP-CDPs also serve as highly efficient liquid chromatographic stationary phases for separation of polar chiral compounds. The stationary phase can separate racemic alcohols and acids successfully. These chiral compounds can be separated within 8 min under normal-phase mode, and the resolution (RS) range from 1.76 to 3.00. Molecular simulations suggest that chiral recognition is a cooperative interaction based on multiple effects such as host-guest interaction, H-bond and size selection. These findings will provide novel chiral stationary phases for recognition and separation of polar chiral compounds in the fields of separation science and pharmaceutical industry.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Polímeros/química , beta-Ciclodextrinas/química , Álcoois/química , Ligação de Hidrogênio , Porosidade , Estereoisomerismo
16.
J Chromatogr A ; 1626: 461348, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797828

RESUMO

Solid-phase extraction (SPE) is a widely-used and very well-established sample preparation technique for liquid samples. An area of on-going focus for innovation in this field concerns the development of new and improved SPE sorbents that can enhance the sensitivity and/or the selectivity of SPE processes. In this context, mixed-mode ion-exchange sorbents have been developed and commercialised, thereby allowing enhanced capacity and selectivity to be offered by one single material. The ion-selectivity of these materials is such that either anion-exchange or cation-exchange is possible, however one limitation to their use is that more than one sorbent type is required to capture both anions and cations. In this paper, we disclose the design, synthesis and exploitation of a novel SPE sorbent based on microporous polymer microspheres with amphoteric character. We show that it is possible to switch the ion-exchange retention mechanism of the sorbent simply by changing the pH of the loading solution; anion-exchange dominates at low pH, cation-exchange dominates at high pH, and both mechanisms can contribute to retention when the polymer-bound amphoteric species, which are based on the α-amino acid sarcosine (N-methylglycine), are in a zwitterionic state. This is an interesting and useful feature, since it allows distinctly different groups of analytes (acids and bases) to be fractionated using one single amphoteric sorbent with dual-functionality. The sarcosine-based sorbent was applied to the SPE of acidic, basic and amphoteric analytes from ultrapure water, river water and effluent wastewater samples. Under optimised conditions (loading 100 mL of sample at pH 6, washing with 1 mL of MeOH and eluting with an acidic or basic additive in MeOH) the recoveries for most of the compounds were from 57% to 87% for river water and from 61% to 88% for effluent wastewater. We anticipate that these results will lay the basis for the development of a new family of multifunctional sorbents, where two or more separation mechanisms can be embedded within one single, bespoke material optimised for application to challenging chemical separations to give significant selectivity advantages over essentially all other state-of-the-art SPE sorbents.


Assuntos
Ácidos/química , Microesferas , Polímeros/química , Extração em Fase Sólida/métodos , Adsorção , Cátions , Concentração de Íons de Hidrogênio , Troca Iônica , Porosidade , Rios/química , Solventes/química , Águas Residuárias/química , Poluentes Químicos da Água/análise
17.
J Chromatogr A ; 1626: 461354, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797834

RESUMO

The Al-doped mesoporous crystalline material-41 (Al-MCM-41) composite was prepared and applied as fiber coating material of headspace solid-phase microextraction (HS-SPME) for extraction of polycyclic aromatic hydrocarbons (PAHs) from human urine. Five PAHs including acenaphthene, fluorene, phenanthrene, anthracene, and pyrene are chosen as target analytes to evaluate the performance of the material by GC-FID analysis. The mesoporous Al-MCM-41 composite was characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, nitrogen adsorption/desorption measurement, and thermogravimetric analysis. The parameters affecting the extraction efficiency of HS-SPME were investigated. Under the optimal conditions, the method exhibits ideal linearity for target analytes in the range of 0.3-600 ng⋅mL-1 with the coefficients (R2) equal or higher than 0.9906. The enrichment factors are calculated from 540 to 1760. The limits of detection (LODs) and limits of quantitation (LOQs) are between the ranges of 0.06-0.18 and 0.3-0.9 ng⋅mL-1, respectively. The relative standard deviations (RSDs) (n = 5) of intra-day and inter-day are in the ranges of 1.08-7.49% and 2.84-18.3% respectively. The fiber-to-fiber reproducibility (n = 3) is in the range of 6.47-13.9%. The method was successfully applied for the analysis of PAHs in human urine with reasonable recoveries which is ranging from 73.29 to 116.1%.


Assuntos
Alumínio/química , Hidrocarbonetos Policíclicos Aromáticos/urina , Dióxido de Silício/química , Microextração em Fase Sólida/métodos , Adsorção , Cristalização , Humanos , Limite de Detecção , Masculino , Concentração Osmolar , Porosidade , Padrões de Referência , Reprodutibilidade dos Testes , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura , Fatores de Tempo , Difração de Raios X
18.
J Chromatogr A ; 1626: 461358, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797837

RESUMO

In this study, the in-situ conversion of the synthesized Co-Al layered double hydroxide (Co-Al LDH) nanosheets to three dimensional hierarchical zeolitic imidazolate framework-67 (3D HZIF-67) was presented as a cost-effective, highly efficient, flexible and robust sorbent to carry out the microextraction process. In the first stage, the anodized aluminum foil was prepared electrochemically. Then, the Co-Al LDH precursor was constructed on the surface of the previously-prepared anodized Al foil applying in-situ formation approach. The procedure is followed by the conversion of the prepared Co-Al LDH film to 3D HZIF-67 film via a facile solvothermal method without adding cobalt salt. The in-situ prepared 3D HZIF-67-anodized Al was used for the thin film microextraction (TFME) of caffeine. The effective factors in TFME procedure were investigated and optimized through applying Central Composite Design (CCD). In the obtained optimal condition, the calibration curves for TFME-HPLC-UV of caffeine were linear in the range of 1-200 µg L-1 with the coefficient of determination (r2) higher than 0.9915. The limits of detection were 0.33 and 0.38 µg L-1, in water and urine matrices, respectively. Moreover, the enrichment factors (EFs) and absolute recoveries (%AR) were also calculated as 173-198 and 57.1%-65.3%, respectively. The inter-day relative standard deviations (RSDs) were evaluated as the method precision for 20 and 200 µg L-1 of spiked sample and were between 4.9-6.1%. The repeatability of the preparation step was investigated as batch-to-batch reproducibility and it was found to be 4.9%; as a result, the reproducibility of the presented film was approved. Finally, the proposed method was utilized to determine caffeine (as the model analyte) from different types of real samples including urine, coffee, beverage (Pepsi) and shampoo. The obtained recoveries (higher than 88%) confirmed the capability of the method for real sample analysis.


Assuntos
Alumínio/química , Cafeína/isolamento & purificação , Cromatografia Líquida de Alta Pressão/métodos , Cobalto/química , Hidróxidos/química , Imidazóis/química , Raios Ultravioleta , Zeolitas/química , Adsorção , Eletrodos , Limite de Detecção , Microscopia de Força Atômica , Porosidade , Reprodutibilidade dos Testes , Solventes/química , Propriedades de Superfície
19.
J Chromatogr A ; 1626: 461319, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797815

RESUMO

The aim of this study is to model, describe and predict the mass transfer of IgG as a function of the agarose concentration in the protein A stationary phase, taking into account the influence of adsorption on the pore size. Therefore, particle size distribution, bed and bead porosities were examined by light microscopy, pressure-flow behavior and iSEC. Three agarose protein A stationary phases (2 wt%, 4 wt%, 6 wt%) were investigated. The pore size decreased from 116 nm for 2 wt% to 54 nm for 6 wt% and the porosity for the target molecule IgG was reduced by 25%. A shrinking core model approach was used to assess the influence of IgG adsorption on the pore size of the stationary phase and the diffusivity of IgG. Due to IgG adsorption, the pore diameter reduced by 24 nm, which is approximately two times its hydrodynamic diameter. Effective pore diffusivities of IgG were obtained by fitting the general rate model to breakthrough curves. They were in the range between 3.96·10-12m2/s and 6.5·10-12m2/s, decreasing as the agarose concentration increased. The DBC1% has a maximum for the 4 wt% agarose gel, showing optimal tradeoffs between accessibility, specific surface and diffusive mass transfer for IgG. A simple geometrical model was developed to describe the change in pore and filament diameters due to adsorption. The diffusion measured in protein A agarose beads can be described by a modification of the Ogston model. This enables the diffusion measured in protein A agarose networks to be predicted.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Sefarose/química , Adsorção , Cromatografia em Gel , Difusão , Imunoglobulina G/metabolismo , Tamanho da Partícula , Porosidade , Ligação Proteica , Proteína Estafilocócica A/metabolismo
20.
J Chromatogr A ; 1626: 461360, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797839

RESUMO

Conjugated microporous polymers (CMPs) with uniform morphology have shown fascinating application in the separation science. In this study, metal-free Knoevenagel condensation was adopted to prepare spherical sp2 carbon-conjugated microporous polymers, which used tetrakis(4-formylphenyl)methane and 1,4-phenylenediacetonitrile as monomers. Due to the remarkable extraction capability for carbamate pesticides (CPs), the as-synthesized CMPs were fabricated as the coating for solid-phase microextraction (SPME). After optimized SPME parameters (adsorption time, salt concentration, sample pH, adsorption temperature, desorption time, desorption solvent and desorption volume), ten CPs in water samples were quantified by ultrahigh performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). Linearity in the range 0.005-100 ng mL-1 with low detection limits of 0.00060-0.017 ng mL-1 was obtained. The intra-day and inter-day precisions expressed as relative standard deviations were 1.5-8.1% and 1.1-8.0%, respectively. Fiber-to-fiber reproducibility was below 7.3%. The CMPs-SPME-UPLC-MS/MS method was applied to detect trace CPs in real water samples with relative recoveries from 91.8% to 108%.


Assuntos
Carbamatos/análise , Microextração em Fase Sólida/métodos , Poluentes Químicos da Água/análise , Adsorção , Carbamatos/isolamento & purificação , Cromatografia Líquida de Alta Pressão , Praguicidas/análise , Praguicidas/isolamento & purificação , Polímeros/química , Porosidade , Reprodutibilidade dos Testes , Espectrometria de Massas em Tandem , Poluentes Químicos da Água/isolamento & purificação
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