Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 32
Filtrar
1.
Clin Implant Dent Relat Res ; 26(1): 113-126, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38018261

RESUMO

OBJECTIVES: To compare patient-reported outcome measures and additional surgical outcomes after sinus floor elevation (SFE) with osseodensification (OD) versus lateral window (LW), both with simultaneous implant placement. MATERIALS AND METHODS: Twenty participants requiring single-implant rehabilitation with residual bone height (RBH) ≤4 mm were enrolled. Pain experience, quality of life (QoL) via the Oral Health Impact Profile-14 (OHIP-14), analgesics intake, and other symptoms were self-reported for a week on a daily basis. Surgery duration, complications, and implant stability quotient at baseline (ISQ T0 ) and after 6 months (ISQ T6 ) were registered. Participants were followed up for 1 year. RESULTS: From Day 0 (day of surgery) to Day 3, pain experience was significantly lower (p < 0.05) in the OD group. OHIP-14 score was significantly lower (p < 0.05) in the OD group on all postoperative days, except on Day 5. Average analgesics intake was significantly lower (p < 0.001) in the OD group. Surgery mean duration was significantly higher (p < 0.001) in LW compared to OD (71.1 ± 10.4 vs. 32.9 ± 5.3 min). After osseointegration period, all implants were successfully restored with screw-retained crowns. CONCLUSIONS: Within the limitations of this study, it can be concluded that OD and LW techniques were similarly effective in SFE with simultaneous implant placement when RBH ≤ 4 mm. However, OD significantly outperformed LW in pain experience, impact on self-perceived QoL, surgery duration, postoperative edema, and analgesics intake.


Assuntos
Implantes Dentários , Levantamento do Assoalho do Seio Maxilar , Humanos , Implantação Dentária Endóssea/métodos , Qualidade de Vida , Levantamento do Assoalho do Seio Maxilar/métodos , Seio Maxilar/cirurgia , Medidas de Resultados Relatados pelo Paciente , Analgésicos/uso terapêutico , Dor/cirurgia , Resultado do Tratamento
2.
Sensors (Basel) ; 22(4)2022 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-35214388

RESUMO

The number of incidents between unmanned aerial vehicles (UAVs) and aircrafts at airports and airfields has been increasing over the last years. To address the problem, in this paper we describe a portable system capable of protecting areas against unauthorized UAVs, which is based on the use of low-cost SDR (software defined radio) platforms. The proposed anti-UAV system supports target localization and integrates effective jamming techniques with the generation of global positioning system (GPS) spoofing signals aimed at the drone. Real-life tests of the implemented prototype have shown that the proposed approach is capable of stopping the reliable reception of radionavigation signals and can also divert or even take control of unauthorized UAVs, whose flight path depends on the information obtained by the GPS system.

3.
Int J Oral Maxillofac Implants ; 36(6): 1104-1110, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34919606

RESUMO

PURPOSE: This systematic review aimed to appraise the available evidence on the clinical characteristics produced by osseodensification drilling compared with the conventional drilling technique. MATERIALS AND METHODS: Five databases (PubMed, Google Scholar, LILACS, EMBASE, and CENTRAL) were searched up to July 2020. Randomized clinical trials (RCTs) and nonrandomized studies of interventions (NRSIs) that compared osseodensification drilling with conventional drilling in humans were included. Random-effects meta-analyses of standardized mean difference (MD) with 95% confidence intervals (CI) and risk ratio were performed. RESULTS: Three NRSIs fulfilled the inclusion criteria, and all were scored as low risk of bias. Meta-analysis showed that the osseodensification drilling technique presented higher average implant stability quotient (ISQ) scores at baseline (MD: 13.1, 95% CI: 10.0 to 16.1, P < .0001) than conventional drilling, with complete homogeneity (I2 = 0.0%). Furthermore, osseodensification drilling presented higher average ISQ scores at follow-up (MD: 5.99, 95% CI: 1.3 to 10.6, P < .0001) than conventional drilling, with high homogeneity (I2 = 73.0%). CONCLUSION: This systematic review showed that osseodensification presented consistently higher ISQ at baseline and at 4 to 6 months after implant placement compared with conventional drilling. However, these results should be carefully interpreted since only three studies were selected in this meta-analysis. In the future, RCTs will be necessary to confirm the consistency of these results.


Assuntos
Implantes Dentários , Humanos
4.
J Funct Biomater ; 12(4)2021 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-34940545

RESUMO

The ideal positioning of immediate implants in molar extraction sockets often requires the osteotomy to be in the interradicular septum, which can be challenging in some cases, with traditional site preparation techniques. Patients who had undergone molar tooth extraction and immediate implant placement at five different centers, and followed up between August 2015 and September 2020, were evaluated. Inclusion criteria were use of the osseodensification technique for implant site preparation. The primary outcome was septum width measurement pre-instrumentation and osteotomy diameter post expansion. Clinical outcomes, such as implant insertion torque (ISQ) and implant survival rate, were also collected. A total of 131 patients, who received 145 immediate implants, were included. The mean overall septum width at baseline was 3.3 mm and the mean osteotomy diameter post instrumentation was 4.65 mm. A total of ten implants failed: seven within the healing period and three after loading; resulting in a cumulative implant survival rate of 93.1%. This retrospective study showed that osseodensification is a predictable method for immediate implant placement with interradicular septum expansion in molar extraction sockets. Furthermore, it allowed the introduction of a new molar socket classification. In the future, well-designed controlled clinical studies are needed to confirm these results and further explore the potential advantages of this technique.

5.
Front Neurosci ; 15: 663174, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34211364

RESUMO

Flexible polymer neural probes are an attractive emerging approach for invasive brain recordings, given that they can minimize the risks of brain damage or glial scaring. However, densely packed electrode sites, which can facilitate neuronal data analysis, are not widely available in flexible probes. Here, we present a new flexible polyimide neural probe, based on standard and low-cost lithography processes, which has 32 closely spaced 10 µm diameter gold electrode sites at two different depths from the probe surface arranged in a matrix, with inter-site distances of only 5 µm. The double-layer design and fabrication approach implemented also provides additional stiffening just sufficient to prevent probe buckling during brain insertion. This approach avoids typical laborious augmentation strategies used to increase flexible probes' mechanical rigidity while allowing a small brain insertion footprint. Chemical composition analysis and metrology of structural, mechanical, and electrical properties demonstrated the viability of this fabrication approach. Finally, in vivo functional assessment tests in the mouse cortex were performed as well as histological assessment of the insertion footprint, validating the biological applicability of this flexible neural probe for acquiring high quality neuronal recordings with high signal to noise ratio (SNR) and reduced acute trauma.

6.
Sensors (Basel) ; 21(8)2021 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-33917654

RESUMO

Multisite neural probes are a fundamental tool to study brain function. Hybrid silicon/polymer neural probes combine rigid silicon and flexible polymer parts into one single device and allow, for example, the precise integration of complex probe geometries, such as multishank designs, with flexible biocompatible cabling. Despite these advantages and benefiting from highly reproducible fabrication methods on both silicon and polymer substrates, they have not been widely available. This paper presents the development, fabrication, characterization, and in vivo electrophysiological assessment of a hybrid multisite multishank silicon probe with a monolithically integrated polyimide flexible interconnect cable. The fabrication process was optimized at wafer level, and several neural probes with 64 gold electrode sites equally distributed along 8 shanks with an integrated 8 µm thick highly flexible polyimide interconnect cable were produced. The monolithic integration of the polyimide cable in the same fabrication process removed the necessity of the postfabrication bonding of the cable to the probe. This is the highest electrode site density and thinnest flexible cable ever reported for a hybrid silicon/polymer probe. Additionally, to avoid the time-consuming bonding of the probe to definitive packaging, the flexible cable was designed to terminate in a connector pad that can mate with commercial zero-insertion force (ZIF) connectors for electronics interfacing. This allows great experimental flexibility because interchangeable packaging can be used according to experimental demands. High-density distributed in vivo electrophysiological recordings were obtained from the hybrid neural probes with low intrinsic noise and high signal-to-noise ratio (SNR).


Assuntos
Polímeros , Silício , Eletrodos , Fenômenos Eletrofisiológicos
7.
Sci Rep ; 10(1): 21625, 2020 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-33303829

RESUMO

Current research is paying much attention to heterojunction nanostructures. Owing to its versatile characteristics such as stimulating morphology, affluent surface-oxygen-vacancies and chemical compositions for enhanced generation of reactive oxygen species. Herein, we report the hydrothermally synthesized TiO2@MoS2 heterojunction nanostructure for the effective production of photoinduced charge carriers to enhance the photocatalytic capability. XRD analysis illustrated the crystalline size of CTAB capped TiO2, MoS2@TiO2 and L-Cysteine capped MoS2@TiO2 as 12.6, 11.7 and 10.2 nm, respectively. The bandgap of the samples analyzed by UV-Visible spectroscopy are 3.57, 3.66 and 3.94 eV. PL spectra of anatase phase titania shows the peaks present at and above 400 nm are ascribed to the defects in the crystalline structure in the form of oxygen vacancies. HRTEM reveals the existence of hexagonal layered MoS2 formation on the spherical shaped TiO2 nanoparticles at the interface. X-ray photoelectron spectroscopy recommends the chemical interactions between MoS2 and TiO2, specifically, oxygen vacancies. In addition, the electrochemical impedance spectroscopy studies observed that L-MT sample performed low charge transfer resistance (336.7 Ω cm2) that promotes the migration of electrons and interfacial charge separation. The photocatalytic performance is evaluated by quantifying the rate of Congo red dye degradation under visible light irradiation, and the decomposition efficiency was found to be 97%. The electron trapping recombination and plausible photocatalytic mechanism are also explored, and the reported work could be an excellent complement for industrial wastewater treatment.

8.
Small ; 16(51): e2003517, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33236819

RESUMO

Despite the progress achieved in nanomedicine during the last decade, the translation of new nanotechnology-based therapeutic systems into clinical applications has been slow, especially due to the lack of robust preclinical tissue culture platforms able to mimic the in vivo conditions found in the human body and to predict the performance and biotoxicity of the developed nanomaterials. Organ-on-a-chip (OoC) platforms are novel microfluidic tools that mimic complex human organ functions at the microscale level. These integrated microfluidic networks, with 3D tissue engineered models, have been shown high potential to reduce the discrepancies between the results derived from preclinical and clinical trials. However, there are many challenges that still need to be addressed, such as the integration of biosensor modules for long-time monitoring of different physicochemical and biochemical parameters. In this review, recent advances on OoC platforms, particularly on the preclinical validation of nanomaterials designed for cancer, as well as the current challenges and possible future directions for an end-use perspective are discussed.


Assuntos
Microfluídica , Nanomedicina , Humanos , Dispositivos Lab-On-A-Chip , Análise de Sequência com Séries de Oligonucleotídeos , Engenharia Tecidual
9.
Opt Express ; 28(22): 32302-32315, 2020 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-33114919

RESUMO

This work reports on high extraction efficiency in subwavelength GaAs/AlGaAs semiconductor nanopillars. We achieve up to 37-fold enhancement of the photoluminescence (PL) intensity from sub-micrometer (sub-µm) pillars without requiring back reflectors, high-Q dielectric cavities, nor large 2D arrays or plasmonic effects. This is a result of a large extraction efficiency for nanopillars <500 nm width, estimated in the range of 33-57%, which is much larger than the typical low efficiency (∼2%) of micrometer pillars limited by total internal reflection. Time-resolved PL measurements allow us to estimate the nonradiative surface recombination of fabricated pillars. We conclusively show that vertical-emitting nanopillar-based LEDs, in the best case scenario of both reduced surface recombination and efficient light out-coupling, have the potential to achieve notable large external quantum efficiency (∼45%), whereas the efficiency of large µm-pillar planar LEDs, without further methods, saturates at ∼2%. These results offer a versatile method of light management in nanostructures with prospects to improve the performance of optoelectronic devices including nanoscale LEDs, nanolasers, single photon sources, photodetectors, and solar cells.

10.
Int J Pharm ; 586: 119590, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32621946

RESUMO

Tolerance inducing vaccines have re-appeared in recent years as a mean to re-establish immunological tolerance in the context of autoimmune disease. In the case of multiple sclerosis, several myelin-related peptides have been identified. The use of microneedles (MNs) allows the painless administration of molecules to the epidermal and intradermal space. This approach has been considered particularly promising in the scope of vaccination as the skin represents an immunologically super-active organ. This work explores the preparation of a MN patch that can deliver immunologically active peptides foreseeing the establishment of tolerance in the context of multiple sclerosis. A new MN design was achieved by microfabrication. The patches are composed of a dense MN array containing 33 × 33 needles with 200 or 125 µm diameter and height around 600 µm. Polymeric MNs composed by poly(vinyl alcohol), poly(vinyl pyrrolidone) and chitosan were successfully obtained, replicating the silicon masters morphology. The polymer MN patches showed to perforate pig skin, reaching more than 400 µm depth of penetration when assessed using agarose as a model for the skin viscoelastic properties. The MNs with 200 µm diameter showed improved mechanical properties in comparison to 125 µm diameter MNs. The presence of chitosan in the MN structure was explored and found not to affect mechanical properties or significantly alter the drug loading or release profile. The immunomodulatory peptide associated with the proteolipid protein PLP139-151 was loaded in 200 µm diameter MN patch and it is released in physiological conditions at therapeutic doses of the peptide, putting forward this strategy to integrate a new tolerance-inducing therapy for multiple sclerosis successfully.


Assuntos
Vacinas , Administração Cutânea , Animais , Sistemas de Liberação de Medicamentos , Microinjeções , Agulhas , Peptídeos , Pele , Suínos
11.
J Mater Chem B ; 8(23): 4990-5013, 2020 06 21.
Artigo em Inglês | MEDLINE | ID: mdl-32409810

RESUMO

The 2D layered structured material with unique surface terminations and properties have showed great potential in variety of biomedical research fields including drug delivery and cancer therapeutics which forms the major focus of this review. MXenes as a multifunctional two-dimensional (2D) nanomaterial, has also received momentous research interest in oncology resulting from its intriguing structure and fascinating properties of magnetism and photodynamic properties such as luminescent, conductivity, magnetism, non-toxicity and its bio compatibility. This reported review intends to cover exclusively the synthesis and utilization of MXenes in oncological applications, and subsequently its future outlook in cancer therapeutic, diagnostic and theranostics. The versatile and unique physio-chemistry of MXenes permits fine tuning of its properties towards oncological applications ranging from the cancer therapeutic (e.g., photothermal therapy, photodynamic therapy, radiation therapy, chemotherapy) to cancer imaging (e.g., CT/MRI/PA imaging) as well as cancer theranostic applications. We have started the discussion by portraying the broad picture of physio-chemical aspects of MXenes followed by its drug delivery functionalities. Subsequently, ROS mediated therapeutic strategies of photodynamic therapy and radiotherapy as well as light triggered functionalities of MXenes were detailed comprehensively. In the middle of the gallery, various imaging and sensing aspects of MXenes were elucidated. Finally, we have concluded by explaining the combined therapy and diagnostic functions (theranostics) of MXenes. To put it in perspective, the current challenges and new opportunities in MXenes also discussed will give great realistic insights to motivate further research in realizing MXene as an intelligent oncological tool.


Assuntos
Antineoplásicos/química , Carbono/química , Neoplasias/diagnóstico por imagem , Nitrogênio/química , Elementos de Transição/química , Animais , Antineoplásicos/uso terapêutico , Carbono/uso terapêutico , Humanos , Nanoestruturas/química , Neoplasias/tratamento farmacológico , Neoplasias/metabolismo , Nitrogênio/uso terapêutico , Tamanho da Partícula , Propriedades de Superfície , Elementos de Transição/uso terapêutico
12.
Biomolecules ; 9(11)2019 11 09.
Artigo em Inglês | MEDLINE | ID: mdl-31717547

RESUMO

Madeira wine (MW) oxidative aging results in the formation of several key aromas. Little is still known about their odor relevance to the aroma of the most commercialized MWs. This report presents an in-depth study of the odor impact of sotolon in MW blends. First, its odor perception was estimated in MWs according to ASTM E679, testing different 3-year-old (3-yo) commercial blends. The odor relevance of sotolon in the aroma of 3-, 5-, and 10-yo commercial blends (89 MWs) was then appraised by calculating its Odor Activity Value (OAV), after determining its content by RP-HPLC-MS/MS. The sotolon odor perception in MW was as low as 23 µg/L, although it was found that little differences in the wine matrix influenced its perception. OAVs varied between 0.1 and 22, increasing with the blend age. Considering that 16% of the OAVs are higher than 10 (mostly ≥ 10-yo), sotolon was found to be a key contributor to the overall aroma MW blends.


Assuntos
Furanos/química , Odorantes/análise , Vinho , Cromatografia Líquida de Alta Pressão , Furanos/isolamento & purificação , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Oxirredução , Espectrometria de Massas em Tandem
13.
J Pers Med ; 9(4)2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31731656

RESUMO

Microneedles (MNs) have been extensively explored in the literature as a means to deliver drugs in the skin, surpassing the stratum corneum permeability barrier. MNs are potentially easy to produce and may allow the self-administration of drugs without causing pain or bleeding. More recently, MNs have been investigated to collect/assess the interstitial fluid in order to monitor or detect specific biomarkers. The integration of these two concepts in closed-loop devices holds the promise of automated and minimally invasive disease detection/monitoring and therapy. These assure low invasiveness and, importantly, open a window of opportunity for the application of population-specific and personalised therapies.

14.
Micromachines (Basel) ; 10(9)2019 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-31540268

RESUMO

Integration of point-of-care assays can be facilitated with the use of actuated magnetic beads (MB) to perform testing in less expensive settings to enable the delivery of cost-effective care. In this paper we present six different designs of planar microelectromagnets traps (MEMT) with four external coils in series and one central coil connected for an opposite direction of manipulation of MB in microfluidic flows. The development of a simulation tool facilitated the rapid and efficient optimization of designs by presenting the influence of system variables on real time concentrations of MB. Real time experiments are in good agreement with the simulations and showed that the design enabled synchronous concentration and dispersion of MB on the same MEMT. The yield of local concentration is seen to be highly dependent on coil design. Additional coil turns between the central and external coils (inter-windings) doubled magnetic concentration and repulsion with no significant electrical resistance increase. The assemblage of a copper microchannel closed loop cooling system to the coils successfully eliminated the thermal drift promoted by joule heating generated by applied current.

15.
Sci Rep ; 9(1): 8032, 2019 05 29.
Artigo em Inglês | MEDLINE | ID: mdl-31142796

RESUMO

Liquid biopsy offers unique opportunities for low invasive diagnosis, real-time patient monitoring and treatment selection. The phenotypic and molecular profile of circulating tumor cells (CTCs) can provide key information about the biology of tumor cells, contributing to personalized therapy. CTC isolation is still challenging, mainly due to their heterogeneity and rarity. To overcome this limitation, a microfluidic chip for label-free isolation of CTCs from peripheral blood was developed. This device, the CROSS chip, captures CTCs based on their size and deformability with an efficiency of 70%. Using 2 chips, 7.5 ml of whole blood are processed in 47 minutes with high purity, as compared to similar technologies and assessed by in situ immunofluorescence. The CROSS chip performance was compared to the CellSearch system in a set of metastatic colorectal cancer patients, resulting in higher capture of DAPI+/CK+/CD45- CTCs in all individuals tested. Importantly, CTC enumeration by CROSS chip enabled stratification of patients with different prognosis. Lastly, cells isolated in the CROSS chip were lysed and further subjected to molecular characterization by droplet digital PCR, which revealed a mutation in the APC gene for most patient samples analyzed, confirming their colorectal origin and the versatility of the technology for downstream applications.


Assuntos
Separação Celular/instrumentação , Neoplasias Colorretais/diagnóstico , Dispositivos Lab-On-A-Chip , Células Neoplásicas Circulantes , Proteína da Polipose Adenomatosa do Colo/genética , Idoso , Linhagem Celular Tumoral , Neoplasias Colorretais/sangue , Neoplasias Colorretais/genética , Neoplasias Colorretais/patologia , Análise Mutacional de DNA , Desenho de Equipamento , Feminino , Humanos , Biópsia Líquida/instrumentação , Biópsia Líquida/métodos , Masculino , Mutação , Reação em Cadeia da Polimerase , Valores de Referência , Sensibilidade e Especificidade
16.
Sensors (Basel) ; 18(10)2018 Oct 13.
Artigo em Inglês | MEDLINE | ID: mdl-30322147

RESUMO

Several devices and measurement approaches have recently been developed to perform ballistocardiogram (BCG) and seismocardiogram (SCG) measurements. The development of a wireless acquisition system (hardware and software), incorporating a novel high-resolution micro-electro-mechanical system (MEMS) accelerometer for SCG and BCG signals acquisition and data treatment is presented in this paper. A small accelerometer, with a sensitivity of up to 0.164 µs/µg and a noise density below 6.5 µg/ Hz is presented and used in a wireless acquisition system for BCG and SCG measurement applications. The wireless acquisition system also incorporates electrocardiogram (ECG) signals acquisition, and the developed software enables the real-time acquisition and visualization of SCG and ECG signals (sensor positioned on chest). It then calculates metrics related to cardiac performance as well as the correlation of data from previously performed sessions with echocardiogram (ECHO) parameters. A preliminarily clinical study of over 22 subjects (including healthy subjects and cardiovascular patients) was performed to test the capability of the developed system. Data correlation between this measurement system and echocardiogram exams is also performed. The high resolution of the MEMS accelerometer used provides a better signal for SCG wave recognition, enabling a more consistent study of the diagnostic capability of this technique in clinical analysis.


Assuntos
Balistocardiografia/instrumentação , Doenças Cardiovasculares/diagnóstico , Técnicas de Diagnóstico Cardiovascular/instrumentação , Processamento de Sinais Assistido por Computador , Acelerometria/instrumentação , Adulto , Idoso , Balistocardiografia/métodos , Eletrocardiografia , Desenho de Equipamento , Feminino , Frequência Cardíaca/fisiologia , Humanos , Masculino , Sistemas Microeletromecânicos , Pessoa de Meia-Idade , Razão Sinal-Ruído , Vibração , Tecnologia sem Fio
17.
Nanoscale ; 10(39): 18613-18621, 2018 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-30259940

RESUMO

Silicon nanopillar (NP) arrays are known to exhibit efficient light trapping and broadband absorption of solar radiation. In this study, we consider the effect of deep subwavelength sidewall scalloping (DSSS) on the broadband absorption of the arrays. Practically, the formation of DSSS is a side effect of top-down dry etching of NP arrays of several microns height. We use finite-difference time-domain electromagnetic calculations to show that the presence of DSSS can result in efficient excitation of optical modes in both the arrays and the underlying substrates. We demonstrate a broadband absorption enhancement of >10% in a DSSS-NP array with an underlying substrate. Finally, we use device calculations to examine the effect of DSSS on the electrical performance of a photovoltaic cell, as the main concern is the degradation of the open-circuit voltage due to surface recombination (DSSS results in higher surface-to-volume ratio). We show that the effect of DSSS on open-circuit voltage is negligible. Finally, deep-subwavelength sidewall features offer a new, interesting photon management strategy towards absorption enhancement.

18.
Sensors (Basel) ; 18(7)2018 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-29954089

RESUMO

The present work provides a detailed description on quantitative 3D magnetic field reconstruction using a scanning magnetoresistance microscopy setup incorporating a 19.5 μm × 2.5 μm magnetoresistive sensor. Therefore, making use of a rotation stage, 11 nm thick ferromagnetic CoFe elements with 20 μm × 5 μm planar size were measured along different sensor axes and converted into cartesian coordinate magnetic field components by use of the analytical coordinate transform equations. The reconstruction steps were followed and validated by numerical simulations based on a field averaging model caused by a non-negligible sensor volume. Detailed in-plane magnetic component reconstruction with ability to reconstruct sub-micrometer features is achieved. A discussion on the limiting factors for optimal resolution is presented.

19.
Anal Chim Acta ; 1020: 30-40, 2018 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-29655426

RESUMO

Sample preparation from complex matrixes with minute DNA content could highly benefit from the miniaturization of solid phase extraction (SPE) based devices due to an increased surface area-to-volume ratio. However, the adaptation of "bench-top" based protocols for DNA purification to miniaturized devices is not as straightforward as it might seem, and several issues need to be considered. A careful evaluation of DNA extraction and purification protocols needs to be performed, taking into account the complexity of such samples, and in order to facilitate the integration with the subsequent step, normally DNA amplification. In this work a washable and reusable miniaturized device for DNA purification based on microscale solid phase extraction (µSPE), containing a commercial disposable silica membrane as the solid phase for DNA capture, was developed. The DNA purification protocol was firstly optimized by testing a set of different conditions, including buffer composition in all three steps of analysis and incubation during the elution step, with the objective of increasing the DNA yield and facilitating the integration in a miniaturized setting. This protocol was then tested with olive oil samples, including a pretreatment step also developed and optimized in this work. DNA analysis of olive oil samples is of high interest for the detection of fraudulent adulteration with oil from other seeds and for cultivar identification. The results were compared with the commercial NucleoSpin® Food kit regarding efficiency and purity of the DNA extract, by estimating the DNA yield and evaluating the absorbance ratios A260/280 and A260/230. The miniaturized DNA purification device showed better performance than the commercial kit tested, making this method a very promising sample preparation approach for olive oil and other samples with minute DNA content.


Assuntos
DNA de Plantas/isolamento & purificação , Análise de Alimentos , Azeite de Oliva/química , Extração em Fase Sólida , DNA de Plantas/química
20.
J Anal Methods Chem ; 2018: 4393040, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30647986

RESUMO

Sotolon (4,5-dimethyl-3-hydroxy-2,5-dihydrofuran-2-one) is a powerful odorant usually pointed out as being responsible not only for the characteristic curry notes of the finest fortified wines but also for the off-flavour notes in prematurely oxidized white wines. Most methods reported in literature for quantifying sotolon in wines are quite laborious and use large volumes of organic solvents. Thus, in the present study, the development of a simple, fast, and environment-friendly method for the quantification of sotolon in fortified wine is herein presented. The proposed method uses a single-step liquid-liquid extraction followed by RP-LC-MS/MS and was optimized using a full factorial design. The method showed good linearity (R 2 = 0.9999), intra- and interday precision lower than 10% RSD, recovery of about 95%, and high sensitivity (LOQ of 0.04 µg/L). The method was applied to analyse 44 fortified wines from different styles (from dry to sweet wines) and ages (3-115 years old), and it was found that it covers the concentration range usually found for this compound in this kind of alcoholic beverages, which was found to be within 6.3-810 µg/L. Thus, it can be concluded that this method can be used as an accurate tool for the rapid analysis of sotolon, since the early stages of its formation up to long ageing periods.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...