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1.
J Virol ; 98(4): e0125823, 2024 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-38546211

RESUMO

Dengue fever, an infectious disease prevalent in subtropical and tropical regions, currently lacks effective small-molecule drugs as treatment. In this study, we used a fluorescence peptide cleavage assay to screen seven compounds to assess their inhibition of the dengue virus (DENV) NS2B-NS3 protease. DV-B-120 demonstrated superior inhibition of NS2B-NS3 protease activity and lower toxicity compared to ARDP0006. The selectivity index of DV-B-120 was higher than that of ARDP0006. In vivo assessments of the antiviral efficacy of DV-B-120 against DENV replication demonstrated delayed mortality of suckling mice treated with the compound, with 60-80% protection against life-threatening effects, compared to the outcomes of DENV-infected mice treated with saline. The lower clinical scores of DENV-infected mice treated with DV-B-120 indicated a reduction in acute-progressive illness symptoms, underscoring the potential therapeutic impact of DV-B-120. Investigations of DV-B-120's ability to restore the antiviral type I IFN response in the brain tissue of DENV-infected ICR suckling mice demonstrated its capacity to stimulate IFN and antiviral IFN-stimulated gene expression. DV-B-120 not only significantly delayed DENV-2-induced mortality and illness symptoms but also reduced viral numbers in the brain, ultimately restoring the innate antiviral response. These findings strongly suggest that DV-B-120 holds promise as a therapeutic agent against DENV infection and highlight its potential contribution in addressing the current lack of effective treatments for this infectious disease.IMPORTANCEThe prevalence of dengue virus (DENV) infection in tropical and subtropical regions is escalating due to factors like climate change and mosquito vector expansion. With over 300 million annual infections and potentially fatal outcomes, the urgent need for effective treatments is evident. While the approved Dengvaxia vaccine has variable efficacy, there are currently no antiviral drugs for DENV. This study explores seven compounds targeting the NS2B-NS3 protease, a crucial protein in DENV replication. These compounds exhibit inhibitory effects on DENV-2 NS2B-NS3, holding promise for disrupting viral replication and preventing severe manifestations. However, further research, including animal testing, is imperative to assess therapeutic efficacy and potential toxicity. Developing safe and potent treatments for DENV infection is critical in addressing the rising global health threat posed by this virus.


Assuntos
Vírus da Dengue , Dengue , Piperidinas , Animais , Camundongos , Antivirais/química , Antivirais/uso terapêutico , Doenças Transmissíveis , Dengue/tratamento farmacológico , Vírus da Dengue/fisiologia , Endopeptidases/farmacologia , Camundongos Endogâmicos ICR , Piperidinas/administração & dosagem , Inibidores de Proteases/farmacologia , Proteínas não Estruturais Virais/química
2.
Sensors (Basel) ; 23(19)2023 Oct 08.
Artigo em Inglês | MEDLINE | ID: mdl-37837155

RESUMO

This paper proposes a robust symbol timing synchronization scheme for return link initial access based on the Digital Video Broadcasting-Return Channel via Satellite 2nd generation (DVB-RCS2) system for the Low Earth Orbit (LEO) satellite channel. In most cases, the feedforward estimator structure is considered for implementing Time Division Multiple Access (TDMA) packet demodulators such as the DVB-RCS2 system. More specifically, the Non-Data-Aided (NDA) approach, without using any kind of preamble, pilot, and postamble symbols, is applicable for fine symbol timing synchronization. However, it hinders the improvement in estimation accuracy, especially when dealing with short packet lengths during the initial access from the User Terminal (UT) to the Gateway (GW). Moreover, when a UT sends a short random access packet for initial access or resource request to the LEO satellite channel, the conventional schemes suffer from a large Doppler error depending on UT's location in a beam and satellite velocity. To ameliorate these problems, we propose a novel symbol timing synchronization algorithm for GW, and its advantage is confirmed through computer simulation.

3.
Sensors (Basel) ; 22(7)2022 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-35408380

RESUMO

Passive radar is a technology that has huge potential for airspace monitoring, taking advantage of existing transmissions. However, to predict whether particular targets can be measured in a particular scenario, it is necessary to be able to model the received signal. In this paper, we present the results of a campaign in which a Pilatus PC-12 single-engine aircraft was measured with a passive radar system relying on DVB-T transmission from a single transmitter. We then present our work to simulate the bistatic RCS of the aircraft along its flight track, using both the method of moments and the shooting and bouncing ray solvers, assess the uncertainty in the simulations, and compare against the measurements. We find that our simulated RCS values are useful in predicting whether or not detection occurs. However, we see poor agreement between simulated and measured RCS values where measurements are available, which we attribute primarily to the difficulties in extracting RCS measurements from the data and to unmodeled transmission and received path effects.

4.
Sensors (Basel) ; 21(19)2021 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-34640989

RESUMO

The radar geometry defined by a spatially separated transmitter and receiver with a moving object crossing the baseline is considered as a Bistatic Forward Inverse Synthetic Aperture Radar (BFISAR). As a transmitter of opportunity, a Digital Video Broadcast-Terrestrial (DVB-T) television station emitting DVB-T waveforms was used. A system of vector equations describing the kinematics of the object was derived. A mathematical model of a BFISAR signal received after the reflection of DVB-T waveforms from the moving object was described. An algorithm for extraction of the object's image including phase correction and two Fourier transformations applied over the received BFISAR signal-in the range and azimuth directions-was created. To prove the correctness of mathematical models of the object geometry, waveforms and signals, and the image extraction procedure, graphical results of simulation numerical experiments were provided.


Assuntos
Algoritmos , Radar
5.
Sensors (Basel) ; 21(12)2021 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-34201180

RESUMO

The verticals of 5G, such as the automotive, smart grid, and smart cities sectors, will bring new sensors and IoT devices requiring Internet connectivity. Most of these machine-type terminals will be sparsely distributed, covering a very large geographical area and, from time to time, will have to update their software, firmware, and/or other relevant data. Given this situation, one viable solution to implement the "Over-the-Air" update of these IoT terminals can be done with the aid of GEO satellite systems. However, due to the ultra-dense radio frequency reuse factor that contemporary High-Throughput Satellite (HTS) systems implement in the access link to serve the IoT terminals, the use of a time-packed Free Space Optical (FSO) link represents a practical solution to avoid the bottleneck that the satellite gateway experiences in the feeder link. The performance of both Detect-and-Forward and Decode-and-Forward relaying strategies are studied, assuming that the single-carrier M-PAM symbols that are transmitted on the optical feeder link are mapped into M-QAM symbols that modulate the multiple sub-carriers of the OFDM-based radio access link. In addition, the benefits of encapsulating the NB-IoT frames into DVB-S2(X) satellite frames is also analyzed in detail. The effects of the impairments introduced in both the optical feeder and radio access links are characterized in detail, and the end-to-end error correction capabilities of the Modulation and Coding Schemes (MCS) defined in the contemporary releases of the NB-IoT and DVB-S2(X) standards are studied for different working regimes.

6.
BMC Infect Dis ; 20(1): 512, 2020 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-32677896

RESUMO

BACKGROUND: The aims of this study were to identify the predictive factors for microbiological diagnosis through disco-vertebral biopsy (DVB) in patients with pyogenic vertebral osteomyelitis (PVO) and negative blood cultures, and compare the performance of DVB under fluoroscopic versus scanographic guidance. METHODS: We performed a cohort study comparing positive and negative DVB among patients with PVO. All cases of PVO undergoing a DVB for microbiological diagnosis in our center were retrospectively reviewed. Infections due to Mycobacterium tuberculosis, infections on foreign device, and non-septic diseases were excluded. Anamnestic, clinical, biological, microbiological, as well as radiological data were collected from medical charts thanks to a standardized data set. RESULTS: A total of 111 patients were screened; 88 patients were included. Microbiological cultures were positive in 53/88 (60.2%) patients. A thickening of the paravertebral tissue ≥10 mm on magnetic resonance imaging (MRI) in axial MR scans was a predictive factor of DVB microbiological positivity (52.4% vs. 13.3%; p = 0.006; OR = 5.4). Overall, 51 DVB were performed under fluoroscopic guidance and 37 under scanographic guidance. Considering lumbar DVB, 25/36 (69.4%) of cases yielded positive results under fluoroscopic guidance versus 5/15 (33.3%) under scanographic guidance (p = 0.02; OR = 4.4). No adverse event linked to DVB was notified. CONCLUSION: Every patient with PVO and negative blood cultures should undergo a DVB. A thickening of the paravertebral tissue ≥10 mm on MRI is associated with a higher rate of positive DVB culture. A lumbar DVB under fluoroscopic guidance is more sensitive than under scanographic guidance to identify the micro-organism involved.


Assuntos
Disco Intervertebral/patologia , Vértebras Lombares/patologia , Osteomielite/diagnóstico , Doenças da Coluna Vertebral/diagnóstico , Infecções Estafilocócicas/diagnóstico , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos de Coortes , Abscesso Epidural/diagnóstico , Abscesso Epidural/patologia , Feminino , Fluoroscopia/métodos , Humanos , Biópsia Guiada por Imagem/métodos , Disco Intervertebral/microbiologia , Vértebras Lombares/microbiologia , Masculino , Pessoa de Meia-Idade , Osteomielite/microbiologia , Osteomielite/patologia , Prognóstico , Estudos Retrospectivos , Fatores de Risco , Doenças da Coluna Vertebral/microbiologia , Doenças da Coluna Vertebral/patologia , Infecções Estafilocócicas/patologia , Tomografia Computadorizada por Raios X/métodos , Adulto Jovem
7.
Sensors (Basel) ; 20(20)2020 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-33053833

RESUMO

This paper presents a novel method of calculating desynchronization between transmitters working in a single frequency digital video broadcasting-terrestrial (DVB-T) network. The described method can be a useful tool for enhancing passive radar operations and improving passive coherent location (PCL) sensors to correct their measurements of target localization. The paper presents the problem of localizing DVB-T transmitters utilized by passive radars, and proposes a novel method based on Time Difference of Arrival (TDoA) techniques to solve the problem. The proposed technique has been validated using real signals collected by a PCL sensor receiver. The details of the experiment and extensive result analysis are also contained in this article.

8.
Anal Bioanal Chem ; 409(12): 3135-3143, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28235995

RESUMO

In affinity chromatography, enrichment of biomolecules is dependent on the selection of affinity sites immobilized onto a suitable support material. A few hydrazide - functionalized materials with surface modification protocols compatible to conventional support materials like silica and cellulose are reported. The study demonstrates the modification/derivatization pathways that can be adopted to modify the support materials with similar surface chemistry like cellulose, poly(GMA/DVB), or diamond. Poly(GMA/DVB) and cellulose represent hydrophilic supports whereas diamond is a hydrophobic support material. SEM images of three materials provide surface morphology whereas FT-IR confirms reaction completion and derivatization. These hydrazide - functionalized materials are applied to fetuin digest for glycopeptides enrichment and subsequently for selectivity and sensitivity assessment. Statistically, poly(GMA/DVB) shows 85.7% sensitivity with specificity of 88.8% in the enrichment experiments. Diamond offers hydrophobic interactions to non-glycopeptides and they co-elute with glycopeptides, resulting in reduced sensitivity down to 69.2%. Poly(GMA/DVB) shows recovery up to 89%, while recovery for cellulose and diamond is 83 and 71%, respectively. The materials enrich mono-N-linked-glycosylated peptide from tryptic digest of chicken avidin spiked in fetuin digest. The hydrazide group density on cellulose, poly(GMA/DVB), and diamond is 2.8, 2.3, and 2.1 mmol/g, respectively; this contributes towards the specificity and sensitivity of designed materials. The materials are also applied to serum samples and enriched glycopeptides characteristic of serum glycoproteins of clinical importance. Therefore this study provides routes for the economical surface modifications of support materials and to fabricate affinity materials with improved efficiency. Graphical Abstract Glycopeptides enrichment by hydrazine affinity.


Assuntos
Celulose/análogos & derivados , Diamante/química , Glicopeptídeos/isolamento & purificação , Hidrazinas/química , Sequência de Aminoácidos , Animais , Galinhas , Cromatografia de Afinidade/métodos , Glicopeptídeos/análise , Glicopeptídeos/sangue , Células HeLa , Humanos , Interações Hidrofóbicas e Hidrofílicas , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos
9.
Sensors (Basel) ; 16(10)2016 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-27690036

RESUMO

This paper investigates the possibility to improve target detection capability in a DVB-T- based passive radar sensor by jointly exploiting multiple digital television channels broadcast by the same transmitter of opportunity. Based on the remarkable results obtained by such a multi-frequency approach using other signals of opportunity (i.e., FM radio broadcast transmissions), we propose appropriate modifications to the previously devised signal processing techniques for them to be effective in the newly considered scenarios. The resulting processing schemes are extensively applied against experimental DVB-T-based passive radar data pertaining to different surveillance applications. The obtained results clearly show the effectiveness of the proposed multi-frequency approaches and demonstrate their suitability for application in the considered scenarios.

10.
Food Chem ; 459: 140312, 2024 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-39003855

RESUMO

Estrogens and their analogues can cause harm to human health through the food chain. Ten estrogens in different milk samples were directly extracted by amphiphilic divinylbenzene/N-vinyl-2-pyrrolidone (DVB/NVP)-Fe3O4@SiO2-based magnetic solid-phase extraction (MSPE) followed by pre-column derivatization and ultra-high performance liquid chromatography tandem mass-spectrometry (UHPLC-MS/MS) detection. Under the optimal conditions, the limits of detection for ten analytes were in the range of 0.05-0.38 ng mL-1 in whole liquid milk matrix and 0.04-3.00 ng g-1 in milk powder matrix. The intra-/inter-day accuracy ranged in 83.4-113.8%, with RSDs in 2.5-15.0%. A total of 15 brands of liquid milk and milk powder samples were analyzed, and only estradiol was detected in three brands of boxed liquid milk within safe range. The proposed sample pretreatment eliminated the common protein precipitation process, improved the sample throughput, and has the potential for routine testing of estrogens and their analogues in market-sale milk samples.


Assuntos
Estrogênios , Contaminação de Alimentos , Leite , Extração em Fase Sólida , Espectrometria de Massas em Tandem , Leite/química , Extração em Fase Sólida/métodos , Extração em Fase Sólida/instrumentação , Cromatografia Líquida de Alta Pressão , Animais , Estrogênios/análise , Estrogênios/isolamento & purificação , Estrogênios/química , Contaminação de Alimentos/análise , Adsorção , Bovinos
11.
Se Pu ; 40(8): 730-735, 2022 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-35903840

RESUMO

A polymer-based strong anion stationary phase modified by quaternary ammoniated allyl glycidyl ether (AGE) for ion chromatography (IC) was developed. It was prepared by surface copolymerization between AGE and the pedant double bonds associated with hydrolyzed poly(glycidylmethacrylate-divinylbenzene) (GMA-DVB) substrate, followed by quaternization with N,N-methyldiethanolamine (a tertiary amine, MDEA). The synthesis conditions were optimized, including the type of organic tertiary amines (MDEA, N,N-dimethylethanolamine, trimethylamine), substrate hydrolysis, the amount of monomer and initiator, reaction temperature and reaction time. The obtained anion stationary phase was characterized by scanning electron microscope and elemental analysis. MDEA was observed to be the best quaternization reagent since the anion exchanger obtained by such reagent showed good separation and suitable retention time towards model inorganic anions. The resulting reason probably lies in higher hydrophilicity of MDEA relative the other two ones. The use of rich epoxy groups of GMA-DVB to introduce the functional groups was commonly used in many previous reports. Here the epoxy groups were firstly hydrolyzed to be diol groups and the pendant double bonds onto the surface of GMA-DVB particles were used to graft AGE. The data achieved indicated that the use of hydrolyzed GMA-DVB substrate would be helpful to reduce anion exchange capacity and unwanted non-ion exchange interaction, in which the rich epoxy groups were converted to hydroxy groups. More important, the obtained anion exchanger after hydrolytic treatment could offer a significantly reduction of retention time (~68%) and a ~1.67-fold higher plate count (take Br- as an example). The apparent capacity of the phase was computed to be 264 µmol/g by content of N data and its effective capacity was measured to be 98.5 µmol/column by the breakthrough curve method. Under the optimal chromatographic conditions, the obtained stationary phase showed baseline separation of seven common inorganic anions in less than 13 min using carbonate-bicarbonate mixed eluent, exhibiting high separation efficiency and peak shape, e. g. 49000 plate/m and 38000 plate/m of the theoretical plate counts respectively for chloride and nitrate, and their asymmetric factor were 1.3 and 1.4. These can be comparable or slightly higher than those of commercial columns. The fitted equation of the eluent concentration and the retention factors of model anions was proved that ion exchange model dominates the retention mechanism of the anion stationary phase. This offers a simple way to prepare anion exchanger and to manipulate anion exchange capacity. The utility of the obtained anion exchanger has been demonstrated to the analysis of tap water.


Assuntos
Compostos de Epóxi , Ânions , Cromatografia por Troca Iônica/métodos , Compostos de Epóxi/química , Interações Hidrofóbicas e Hidrofílicas
12.
Anal Chim Acta ; 1226: 340254, 2022 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-36068056

RESUMO

It is well known that grape aromatic composition is directly correlated to the final wine quality. To determine this composition, a previous stage of selective extraction is necessary, since the aromatic compounds are found in very low concentrations in the grapes. Therefore, in this work, the thin film microextraction technique (TF-SPME) was optimized, for first time, with the aim to analyze the volatile composition of the grape musts. The results obtained with the two commercially available absorbent materials for TF-SPME, polydimethylsiloxane/carboxene (PDMS/CAR) and PDMS/divinylbenzene (PDMS/DVB), were optimized and compared. To carry out the optimization, a randomized factorial design was performed combining the following factors and levels: extraction mode (headspace (HS), or direct immersion (DI)), stirring speed (500 and 1000 rpm), extraction time (1, 3 and 6 h), and extraction temperature (20, 40 and 60 °C). After performing a principal component analysis (PCA) and an analysis of variance (ANOVA) multifactorial, it was concluded that the best conditions for TF-SPME with PDMS/CAR were: direct immersion (DI), 500 rpm, 6 h, and 20 °C, while for TF-SPME with PDMS/DVB no conditions were found that maximized the extraction of most compounds, therefore compromise conditions were chosen: headspace (HS), 500 rpm, 6 h, and 40 °C. Finally, the comparison between the results obtained with both absorbents indicated that the absorbent that extracted better the volatile compounds from the musts with the TF-SPME technique, was PDMS/CAR, under the conditions: direct immersion (DI), 500 rpm, 6 h, and 20 °C.


Assuntos
Compostos Orgânicos Voláteis , Vinho , Cromatografia Gasosa-Espectrometria de Massas/métodos , Compostos Orgânicos/análise , Microextração em Fase Sólida/métodos , Temperatura , Compostos Orgânicos Voláteis/análise , Vinho/análise
13.
Food Chem X ; 15: 100399, 2022 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-36211732

RESUMO

This study examined the changes in metabolites together with the flavor profiles of germinated Sacha inchi seeds during roasting by using gas chromatography. The results indicated that roasting partially increased the browning index, amino acid levels, total phenolic content, and antioxidant capacity, but slightly decreased the levels of reducing sugars. Oxidized and rancid compounds were significantly decreased at a 180 °C roasting temperature. Pyrazine, furan, and pyrrole were Maillard reaction products that were increased at 180 °C of roasting. Roasting at 145 °C for 45 min after germination for 4 days was determined to be the optimal conditions for roasting germinated Sacha inchi seeds, which reduced the off-flavor and burned taste. The roasted germinated Sacha inchi seed contains higher amino acids than raw seed, which could be used as an alternative source for food products and supplements. In addition, the roasted germinated seeds at 4 days were recommended for food applications.

14.
Se Pu ; 38(4): 458-463, 2020 Apr 08.
Artigo em Chinês | MEDLINE | ID: mdl-34213229

RESUMO

A polyaniline/graphene (PANI/G) composite was selected as the coating material to prepare a coated anion-exchange chromatographic stationary phase. First, aniline and graphene were used to prepare the PANI/G composite, which was coated onto the surface of poly(styrene-divinylbenzene) (PS-DVB) microspheres by physical absorption. Then, a series of anion-exchange stationary phases with different exchange capacities were obtained by quaternization using the nitrogen atom of polyaniline as the reactive site. The stationary phase was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and elemental analysis (EA). The results revealed that PANI/G was successfully coated onto the surface of PS-DVB and quaternized. The efficiency of the self-fabricated chromatographic column was evaluated by separating conventional anions and organic acids. The PANI/G-coated PS-DVB anion-exchange chromatographic column that was quaternized eight times showed good separation performance for conventional anions and organic acids.

15.
J Chromatogr A ; 1623: 461154, 2020 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-32505273

RESUMO

Chiral stationary phases (CSPs) have always been research hotspot in enantiomer separation. Currently, most of the CSPs are based on silica platform. In this research, monodisperse, porous glycidyl methacrylate-divinylbenzene copolymer particles (poly(GMA-DVB)) were designed and prepared. Then the GMA was further reacted with ethylenediamine to introduce amino groups onto the polymer, which provide anchoring sites for cellulose derivatives. Herein, Cellulose-tris (3,5-dimethylphenylcarbamate) (CDMPC) was successfully coated onto the polymer microspheres, achieving a stable and successful CSP. The porous structure and the surface moieties of the CSPs were studied in detail. The chromatographic separation was optimized. Hexaconazole,methyl DL-mandelate,benzoin and tebuconazole have been successfully separated on the CSP column, with column efficiency as high as 10,200 plates/m, which is comparable with some silica-based CSPs. The research has indicated that the poly(GMA-DVB) is a promising candidate for constructing CSPs for chiral separation.


Assuntos
Celulose/análogos & derivados , Microesferas , Fenilcarbamatos/química , Polímeros/química , Celulose/química , Cromatografia Líquida de Alta Pressão/métodos , Compostos de Epóxi/química , Metacrilatos/química , Porosidade , Dióxido de Silício/química , Estereoisomerismo , Triazóis/química , Compostos de Vinila/química
16.
Polymers (Basel) ; 12(11)2020 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-33114700

RESUMO

Flexible ultra-compact low-loss optical waveguides play a vital role in the development of soft photonics. The search for suitable materials and innovative fabrication techniques to achieve low loss long polymer optical waveguides and interconnects has proven to be challenging. In this paper, we demonstrate the fabrication of submicron optical waveguides in polydimethylsiloxane (PDMS) using divinylbenzene (DVB) as the photopolymerizable monomer through two-photon polymerization (2PP). We show that the commercial oxime ester photoinitiator Irgacure OXE02 is suitable for triggering the DVB photopolymerization, resulting in a stable and controllable fabrication process for the fabrication of defect-free, 5-cm long waveguides. We further explore a multi-track fabrication strategy to enlarge the waveguide core size up to ~3 µm for better light confinement and reduced cross-talk. In these waveguides, we measured a refractive index contrast on the order of 0.005 and a transmission loss of 0.1 dB/cm at 710 nm wavelength.

17.
Environ Pollut ; 245: 634-641, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30476893

RESUMO

Microplastics are emerging pollutants in water bodies worldwide. The environmental entry areas must be studied to localise their sources and develop preventative and remedial solutions. Rivers are major contributors to the marine microplastics load. Here, we focus on a specific type of plastic microbead (diameter 286-954 µm, predominantly opaque, white-beige) that was repeatedly identified in substantial numbers between kilometres 677 and 944 of the Rhine River, one of Europe's main waterways. Specifically, we aimed (i) to confirm the reported abrupt increase in microbead concentrations between the cities of Leverkusen and Duisburg and (ii) to assess the concentration gradient of these particles along this stretch at higher resolution. Furthermore, we set out (iii) to narrow down the putative entry stretch from 81.3 km, as reported in an earlier study, to less than 20 km according to our research design, and (iv) to identify the chemical composition of the particles and possibly reveal their original purpose. Surface water filtration (mesh: 300 µm, n = 9) at regular intervals along the focal river stretch indicated the concentration of these spherules increased from 0.05 to 8.3 particles m-3 over 20 km. This spot sampling approach was supported by nine suspended solid samples taken between 2014 and 2017, encompassing the river stretch between Leverkusen and Duisburg. Ninety-five percent of microbeads analysed (202/212) were chemically identified as crosslinked polystyrene-divinylbenzene (PS-DVB, 146/212) or polystyrene (PS, 56/212) via Raman or Fourier-transform infrared spectroscopy. Based on interpretation of polymer composition, surface structure, shape, size and colour, the PS(-DVB) microbeads are likely to be used ion-exchange resins, which are commonly applied in water softening and various industrial purification processes. The reported beads contribute considerably to the surface microplastic load of the Rhine River and their potential riverine entry area was geographically narrowed down.


Assuntos
Monitoramento Ambiental/métodos , Poliestirenos/análise , Poluentes Químicos da Água/análise , Poluentes Ambientais/análise , Europa (Continente) , Microesferas , Plásticos/análise , Rios/química
18.
Talanta ; 199: 347-354, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-30952269

RESUMO

If strong cation exchange chromatography (SCX) is combined with ion-pair chromatography, then the solute could be retained selectively with the power of mixed separation modes. This combination is termed selectivity enhanced strong cation exchange chromatography (SE-SCX). Macroporous polystyrene-divinylbenzene (PS/DVB) resin with sulfonate coating that conveys ion exchange and reversed phase characteristics was employed. Sodium dodecyl sulfate (SDS) was utilized as a selectivity modifier and an ion-pair reagent. This separation strategy is exploited for a challenging simultaneous separation of peptide variants having similar isoelectric points (pIs) and comparable retention behaviour. Insulin variants were used as a model in this study. The selective separation of insulin and five structurally-related analogues namely; ASPART, LISPRO, GLULISIN, GLARGIN, and DETEMIR was conducted using gradient elution mode. Three eluents were used for the separation of the target compounds. Eluent A was a mixture of acetonitrile and 10 mmol L-1 SDSat ratio (1:1) and was kept at 20% through the run. Eluent B was 20 mmol L-1 KH2PO4 adjusted at pH = 4.0 and eluent C was eluent B plus 1 mol L-1 NaCl that was increased linearly till 80% at 20 min. It was found that the retention of the tested variants can be modeled mainly by electrostatic interaction that might be hydrophobically-assisted. The developed method was validated in accordance with ICH guidelines and was appropriate for the intended purposes. Finally, this study introduces SE-SCX as a new selective separation strategy for peptides and proteins that may open the door for novel mixed mode perspectives in protein analysis.


Assuntos
Peptídeos/análise , Peptídeos/química , Cromatografia por Troca Iônica , Interações Hidrofóbicas e Hidrofílicas
19.
Food Res Int ; 123: 75-87, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31285025

RESUMO

Ethanol is the major matrix constituent of beer and has been reported as an important interfering volatile during headspace solid phase microextraction (HS-SPME) of minor compounds due to its displacement effect. The addition of a thin hydrophobic polydimethylsiloxane (PDMS) layer on a commercial divinylbenzene/Carboxen/PDMS (DVB/Car/PDMS) fiber was evaluated, for the first time, to minimize the displacement effect caused by ethanol in the quantitative determination of volatile profile of five stages of brewing. Analysis were performed through gas chromatography coupled to mass spectrometry detector. The extractive capacity of the PDMS-overcoated fiber was superior to the commercial analogous fiber, since the modified version extracted a greater number of compounds (61 versus 45) and allowed to obtain 20% more of total chromatographic area than the commercial fiber. The ethanol content of model solutions (0, 4, 8 and 12%) did not result in significant differences in responses neither to polar nor to medium polar or nonpolar analytes when PDMS-overcoated fiber was used. On the other hand, a displacement effect was observed when polar compounds were extracted by the commercial fiber. There was no need to prepare different analytical curves with distinct ethanol levels close to those found in each brewing stage, when PDMS-overcoated fiber was used. This approach turns the analytical method simpler, less laborious and time consuming. It showed adequate linearity, sensitivity, repeatability and intermediate precision. A heat map displayed the quantitative differences in the volatile profile of each stage of brewing. Mashing stood out in relation to the others steps by the highest levels of higher alcohols. Boiling was characterized by the highest levels of Maillard reaction products, while fermentation, maturation and pasteurization were discriminated by a major presence of esters. Terpenes were incorporated to the wort during boiling or fermentation and the concentration of these compounds remained similar throughout the subsequent brewing steps.


Assuntos
Manipulação de Alimentos , Microextração em Fase Sólida , Compostos Orgânicos Voláteis/análise , Dimetilpolisiloxanos/química , Ésteres/análise , Estudos de Avaliação como Assunto , Cromatografia Gasosa-Espectrometria de Massas , Polivinil/química , Terpenos/análise
20.
Data Brief ; 25: 104268, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31453285

RESUMO

This data article describes the analysis of volatile organic compounds (VOCs) in 44 samples of cocoa bean shells (CBS) obtained from cocoa beans of diverse cultivars and collected in different geographical origins. The volatile compounds were extracted by headspace solid-phase microextraction (HS-SPME) method and then analyzed by gas chromatography coupled to a quadrupole mass spectrometry GC-qMS. The retention times, identification and semi-quantification of 101 VOCs are reported. Data collected on the volatile profile of CBS samples using E-nose analysis are also available. Additional data related to physicochemical characteristics and color analysis for CBS samples are reported. Further interpretation and discussion on these datasets can be found in the related article entitled "Assessment of volatile fingerprint by HS-SPME/GC-qMS and E-nose for the classification of cocoa bean shells using chemometrics" (Barbosa-Pereira et al., 2019).

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