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1.
Front Public Health ; 9: 669190, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34026718

RESUMO

Powerline interference (PLI) is a major source of interference in the acquisition of electroencephalogram (EEG) signal. Digital notch filters (DNFs) have been widely used to remove the PLI such that actual features, which are weak in energy and strongly connected to brain states, can be extracted explicitly. However, DNFs are mathematically implemented via discrete Fourier analysis, the problem of overlapping between spectral counterparts of PLI and those of EEG features is inevitable. In spite of their effectiveness, DNFs usually cause distortions on the extracted EEG features, which may lead to incorrect diagnostic results. To address this problem, we investigate an adaptive sparse detector for reducing PLI. This novel approach is proposed based on sparse representation inspired by self-adaptive machine learning. In the coding phase, an overcomplete dictionary, which consists of redundant harmonic waves with equally spaced frequencies, is employed to represent the corrupted EEG signal. A strategy based on the split augmented Lagrangian shrinkage algorithm is employed to optimize the associated representation coefficients. It is verified that spectral components related to PLI are compressed into a narrow area in the frequency domain, thus reducing overlapping with features of interest. In the decoding phase, eliminating of coefficients within the narrow band area can remove the PLI from the reconstructed signal. The sparsity of the signal in the dictionary domain is determined by the redundancy factor. A selection criteria of the redundancy factor is suggested via numerical simulations. Experiments have shown the proposed approach can ensure less distortions on actual EEG features.


Assuntos
Algoritmos , Eletroencefalografia , Encéfalo , Análise de Fourier , Aprendizado de Máquina
2.
Analyst ; 146(11): 3440-3448, 2021 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-33955444

RESUMO

The extraction and quantification of leaf pigments are easy, fast, and cheap procedures; on the other hand, diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy associated with chemometrics tools could offer new insights into leaf biochemical composition. We aimed to boost the classic leaf pigment quantification, adding leaf biochemical information derived from DRIFT spectroscopy + principal component analysis, using the same leaf pigment extract produced by the classical quantification method. We performed a dose-response experiment using P as the limiting nutrient, and maize (Zea mays L.) as a plant-test. After 45 d of growth, we evaluated the effects of P fertilization in total maize shoot biomass, P shoot accumulation, leaf pigment quantification by UV-Vis, and the evaluation of biochemical variations by DRIFT spectroscopy analysis associated with a chemometric approach in the same leaf extract used for pigment quantification. P fertilization raised biomass accumulation (∼7.4×), P uptake (∼2.3×), and total chlorophyll a and b contents (∼2.1×). DRIFT spectroscopy analysis of extracted pigments revealed an elevated content of proteins and polysaccharides at high P availability. At low P availability, we found a low efficiency of N metabolism suggested by the accumulation of inorganic N forms. DRIFT spectroscopy applied together with the classic leaf pigment extraction and quantification method is a novel and promising tool for plant nutrition studies as a DRIFT spectroscopy metabolic profile protocol.


Assuntos
Folhas de Planta , Zea mays , Clorofila A , Análise de Fourier , Espectroscopia de Infravermelho com Transformada de Fourier , Análise Espectral
4.
J Biol Phys ; 47(2): 103-115, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33905049

RESUMO

The paper delves into the plausibility of applying fractal, spectral, and nonlinear time series analyses for lung auscultation. The thirty-five sound signals of bronchial (BB) and pulmonary crackle (PC) analysed by fast Fourier transform and wavelet not only give the details of number, nature, and time of occurrence of the frequency components but also throw light onto the embedded air flow during breathing. Fractal dimension, phase portrait, and sample entropy help in divulging the greater randomness, antipersistent nature, and complexity of airflow dynamics in BB than PC. The potential of principal component analysis through the spectral feature extraction categorises BB, fine crackles, and coarse crackles. The phase portrait feature-based supervised classification proves to be better compared to the unsupervised machine learning technique. The present work elucidates phase portrait features as a better choice of classification, as it takes into consideration the temporal correlation between the data points of the time series signal, and thereby suggesting a novel surrogate method for the diagnosis in pulmonology. The study suggests the possible application of the techniques in the auscultation of coronavirus disease 2019 seriously affecting the respiratory system.


Assuntos
Auscultação , Aprendizado de Máquina , Sons Respiratórios/diagnóstico , Processamento de Sinais Assistido por Computador , COVID-19/fisiopatologia , Análise de Fourier , Humanos , Análise de Componente Principal
5.
Int J Mol Sci ; 22(5)2021 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-33800802

RESUMO

Multiphoton microscopy has recently passed the milestone of its first 30 years of activity in biomedical research. The growing interest around this approach has led to a variety of applications from basic research to clinical practice. Moreover, this technique offers the advantage of label-free multiphoton imaging to analyze samples without staining processes and the need for a dedicated system. Here, we review the state of the art of label-free techniques; then, we focus on two-photon autofluorescence as well as second and third harmonic generation, describing physical and technical characteristics. We summarize some successful applications to a plethora of biomedical research fields and samples, underlying the versatility of this technique. A paragraph is dedicated to an overview of sample preparation, which is a crucial step in every microscopy experiment. Afterwards, we provide a detailed review analysis of the main quantitative methods to extract important information and parameters from acquired images using second harmonic generation. Lastly, we discuss advantages, limitations, and future perspectives in label-free multiphoton microscopy.


Assuntos
Microscopia de Fluorescência por Excitação Multifotônica/métodos , Absorção de Radiação , Anisotropia , Análise de Fourier , Microscopia de Polarização/métodos , Microtomia/métodos , Imagem Óptica/métodos , Fotodegradação , Fótons , Microscopia de Geração do Segundo Harmônico/métodos , Manejo de Espécimes/métodos , Fixação de Tecidos/métodos , Análise de Ondaletas
6.
Braz Oral Res ; 35: e034, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33729279

RESUMO

The objective of this study was to apply elliptic Fourier analysis (EFA) to find shape differences among skeletal growth patterns in both radiographic and tomographic panoramic views, controlling for asymmetry. Lateral and panoramic images were obtained from 350 patients. After screening patients with asymmetric linear and angular values and natural asymmetric hemimandibular shape, 240 patients were included in the study: 48 with tomographic information and 192 with radiographic information. The images were classified according to the mandibular plane angle and the ANB angle. Mandibular contours were digitized on the panoramic images and EFA was performed with 20 harmonics, filtering rotation, translation and size properties. As there were no differences between radiographic and tomographic panoramic mandibular contours and normal distribution was found in all groups, MANOVA was conducted to determine differences using a Hotelling's p-values with Bonferroni correction and an XY graph tool was applied to visualize these differences graphically. A 95% confidence level was used. Significative differences were found among hypodivergent, normodivergent, and hyperdivergent patterns in Class I, II, and III (p < 0.05), located mainly in the symphyseal region. The results of this study suggest that EFA is a useful tool to mathematically analyze mandibular contours and their morphological differences given by facial biotypes. This method could improve the precision of the mandibular prediction models.


Assuntos
Mandíbula , Cefalometria , Análise de Fourier , Humanos , Mandíbula/diagnóstico por imagem
7.
J Math Biol ; 82(5): 37, 2021 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-33721104

RESUMO

In the spreading of infectious diseases, an important number to determine is how many other people will be infected on average by anyone who has become infected themselves. This is known as the reproduction number. This paper describes a non-parametric inverse method for extracting the full transfer function of infection, of which the reproduction number is the integral. The method is demonstrated by applying it to the timeline of hospitalisation admissions for covid-19 in the Netherlands up to May 20 2020, which is publicly available from the site of the Dutch National Institute of Public Health and the Environment (rivm.nl).


Assuntos
Número Básico de Reprodução/estatística & dados numéricos , COVID-19/epidemiologia , COVID-19/transmissão , Modelos Estatísticos , Pandemias , SARS-CoV-2 , Simulação por Computador , Análise de Fourier , Humanos , Conceitos Matemáticos , Modelos Biológicos , Países Baixos/epidemiologia , Pandemias/estatística & dados numéricos , Estatísticas não Paramétricas
8.
Spectrochim Acta A Mol Biomol Spectrosc ; 254: 119665, 2021 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-33744696

RESUMO

Among skin cancers, melanoma is the lethal form and the leading cause of death in humans. Melanoma begins in melanocytes and is curable at early stages. Thus, early detection and evaluation of its metastatic potential are crucial for effective clinical intervention. Fourier transform infrared (FTIR) spectroscopy has gained considerable attention due to its versatility in detecting biochemical and biological features present in the samples. Changes in these features are used to differentiate between samples at different stages of the disease. Previously, FTIR spectroscopy has been mostly used to distinguish between healthy and diseased conditions. With this study, we aim to discriminate between different melanoma cell lines based on their FTIR spectra. Formalin-fixed paraffin embedded samples from three melanoma cell lines (IPC-298, SK-MEL-30 and COLO-800) were used. Statistically significant differences were observed in the prominent spectral bands of three cell lines along with shifts in peak positions. A partial least square discriminant analysis (PLS-DA) model built for the classification of three cell lines showed an overall accuracy of 92.6% with a sensitivity of 85%, 95.75%, 96.54%, and specificity of 97.80%, 92.14%, 98.64% for the differentiation of IPC-298, SK-MEL-30, and COLO-800, respectively. The results suggest that FTIR spectroscopy can differentiate between different melanoma cell lines and thus potentially characterize the metastatic potential of melanoma.


Assuntos
Melanoma , Neoplasias Cutâneas , Linhagem Celular , Análise de Fourier , Humanos , Melanoma/diagnóstico , Neoplasias Cutâneas/diagnóstico , Espectroscopia de Infravermelho com Transformada de Fourier
9.
Anal Methods ; 13(13): 1601-1611, 2021 04 07.
Artigo em Inglês | MEDLINE | ID: mdl-33730137

RESUMO

Due to the outbreak of the COVID-19 pandemic, practicing personal hygiene such as frequent hand sanitising has become a norm. The making of effective hand sanitiser products should follow the recommended formulations, but the high demand worldwide for such affordable products could have made them a candidate for counterfeiting, thus deserving forensic determination and profiling for source determination or supply chain tracing. In this study, determination and discrimination of hand sanitisers was carried out by employing attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy combined with chemometrics. Fifty commercially available hand sanitisers were obtained from the market and analysed. ATR-FTIR profiles of each sanitiser were compared and decomposed by principal component analysis (PCA) followed by linear discriminant analysis (LDA). Physical observation enabled the discrimination of seven samples based on their respective colours, the presence of beads and their colours, and the physical forms of formulations. Subsequently, eight distinct patterns were observed through visual comparison of ATR-FTIR profiles of the remaining 43 samples. An initial unsupervised exploratory PCA model indicated the separation of two main groups with ATR-FTIR profiles similar to those of ethanol and isopropanol, respectively. The PCA score-LDA model provided good predictions, with a 100% correct classification into eight different groups. In conclusion, this study demonstrated a quick determination and discrimination of hand sanitiser samples, allowing screening for any restricted components and sample-to-sample comparison.


Assuntos
Higienizadores de Mão/normas , COVID-19 , Análise de Fourier , Higiene das Mãos , Humanos , Espectroscopia de Infravermelho com Transformada de Fourier
10.
Epidemiol Infect ; 149: e64, 2021 03 04.
Artigo em Inglês | MEDLINE | ID: mdl-33658083

RESUMO

Fourier analysis can provide policymakers useful information for analysing the pandemic behaviours. This paper proposes a Fourier analysis approach for examining the cycle length and the power spectrum of the pandemic by converting the number of deaths due to coronavirus disease 2019 in the US to the frequency domain. Policymakers can control the pandemic by using observed cycle length whether they should strengthen their policy or not. The proposed Fourier method is useful for analysing waves in other medical applications.


Assuntos
COVID-19/mortalidade , Política de Saúde , Pandemias , Análise de Fourier , Humanos , Estados Unidos/epidemiologia
11.
Nat Commun ; 12(1): 1913, 2021 03 26.
Artigo em Inglês | MEDLINE | ID: mdl-33772014

RESUMO

Diffusion is a major molecular transport mechanism in biological systems. Quantifying direction-dependent (i.e., anisotropic) diffusion is vitally important to depicting how the three-dimensional (3D) tissue structure and composition affect the biochemical environment, and thus define tissue functions. However, a tool for noninvasively measuring the 3D anisotropic extracellular diffusion of biorelevant molecules is not yet available. Here, we present light-sheet imaging-based Fourier transform fluorescence recovery after photobleaching (LiFT-FRAP), which noninvasively determines 3D diffusion tensors of various biomolecules with diffusivities up to 51 µm2 s-1, reaching the physiological diffusivity range in most biological systems. Using cornea as an example, LiFT-FRAP reveals fundamental limitations of current invasive two-dimensional diffusion measurements, which have drawn controversial conclusions on extracellular diffusion in healthy and clinically treated tissues. Moreover, LiFT-FRAP demonstrates that tissue structural or compositional changes caused by diseases or scaffold fabrication yield direction-dependent diffusion changes. These results demonstrate LiFT-FRAP as a powerful platform technology for studying disease mechanisms, advancing clinical outcomes, and improving tissue engineering.


Assuntos
Córnea/metabolismo , Espaço Extracelular/metabolismo , Recuperação de Fluorescência Após Fotodegradação/métodos , Microscopia de Fluorescência por Excitação Multifotônica/métodos , Tendões/metabolismo , Animais , Anisotropia , Colágeno/química , Colágeno/metabolismo , Difusão , Análise de Fourier , Microscopia Confocal/métodos , Microscopia Eletrônica de Varredura/métodos , Ratos Sprague-Dawley , Reprodutibilidade dos Testes , Suínos , Engenharia Tecidual/métodos , Tecidos Suporte/química
12.
AJR Am J Roentgenol ; 216(3): 704-717, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33534619

RESUMO

OBJECTIVE. The purpose of this article is to provide a practice-focused review of accelerating musculoskeletal MRI with the use of widely accessible techniques and to assess the effects of such acceleration on the value of musculoskeletal MRI. CONCLUSION. Echo-train compaction with fast radiofrequency pulses, high gradient performance modes, and high receiver bandwidth, as well as basic phase undersampling techniques, affords at least twofold acceleration of musculoskeletal MRI examinations while retaining image quality, comprehensiveness, and diagnostic performance. Optimized efficiency is a cornerstone for adding value to musculoskeletal MRI.


Assuntos
Lista de Checagem , Imageamento por Ressonância Magnética/métodos , Sistema Musculoesquelético/diagnóstico por imagem , Adulto , Análise de Fourier , Humanos , Imageamento por Ressonância Magnética/normas , Masculino , Fatores de Tempo
13.
Poult Sci ; 100(2): 1248-1261, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33518082

RESUMO

Meat quality attributes vary with chicken age. Understanding the relationship between poultry age and the quality of the meat would be beneficial for efficient poultry farming to meet market needs. The Korat hybrid chicken (KC) is a new crossbred chicken whose meat quality is distinct from that of commercial broiler (CB) chickens and has not been well characterized. In this study, we characterized the physico-chemical properties of KC meat and correlate the findings with Raman spectral data. The protein content of KC breast and thigh meat increased with age. The pH of thigh meat decreased, while the water-holding capacity of breast meat increased as the age of the chickens increased. The amount of cholesterol in breast meat decreased as the rearing period was extended. Inosine 5'-monophosphate and guanosine 5'-monophosphate of breast meat decreased as KC grew older. The shear force values of meat from older birds increased concomitantly with an increase in total collagen. Principle component analysis revealed that the meat quality of CB was greatly different from that of KC meat. High shear force values of KC meat at 20 wk of age were well correlated with an increase in the ß-sheet structure (amide I) and amide III of collagen. Raman spectra at 3,207 cm-1 and relative α-helical content were negatively correlated with shear force values of KC breast meat. These could be used as markers to evaluate KC meat quality.


Assuntos
Galinhas/crescimento & desenvolvimento , Carne/normas , Fatores Etários , Animais , Galinhas/classificação , Colesterol/análise , Colágeno/análise , Ácidos Graxos/análise , Análise de Fourier , Guanosina Monofosfato/análise , Concentração de Íons de Hidrogênio , Inosina Monofosfato/análise , Carne/análise , Proteínas/análise , Purinas/análise , Resistência ao Cisalhamento , Análise Espectral Raman/métodos
14.
Spectrochim Acta A Mol Biomol Spectrosc ; 252: 119542, 2021 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-33581574

RESUMO

Recent studies have shown that bacteria can also undergo apoptosis, which has gradually attracted researchers' attention. Cisplatin is a first-line drug to treat several cancers, but it can damage beneficial bacteria. Hence it is very important to explore the damage mechanism of cisplatin on beneficial bacteria. In this study, Lactobacillus paracasei, one kind of beneficial bacteria, was used as the model to investigate cisplatin damage. Conventional detection showed that cisplatin induced the apoptosis of Lactobacillus paracasei. Then Fourier transform infrared (FTIR) microspectroscopy was used to detect biomacromolecular changes in Lactobacillus paracasei apoptosis, and the following results were obtained: ① Second derivative IR spectra showed the changes of DNA, proteins, polysaccharides and lipids; ② Peak-area ratios suggested the changes of the protein and lipid structure and the decrease of DNA content; ③ Principal component analysis (PCA) further revealed significant changes in the DNA and protein content/structure. This study may have a new insight into the adverse reaction mechanism of cisplatin on Lactobacillus, moreover, it suggests that FTIR microspectroscopy may be a useful supplementary tool for investigating bacterial apoptosis.


Assuntos
Lactobacillus paracasei , Apoptose , Cisplatino/farmacologia , Análise de Fourier , Espectroscopia de Infravermelho com Transformada de Fourier
15.
J Chromatogr A ; 1640: 461941, 2021 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-33556685

RESUMO

The steadily rising interest in the investigation of interactions between nanomaterials and biological media has also led to an increasing interest in asymmetrical flow field-flow fractionation (AF-FFF). The biggest strength of AF-FFF is the possibility to alter the flow profiles to suit a specific separation problem. In this paper, the influence of an oscillating main flow on the separation efficiency of AF-FFF is investigated. Such oscillations can e.g. be caused by the main pump To investigate the influence of such flow conditions on the separation efficiency in AF-FFF systematically, different oscillation profiles were applied and their influence on the elution profile and the retention times was observed. It could be shown, that the separation mechanism is extremely robust and a fractionation is still possible even under unfavorable conditions.


Assuntos
Fracionamento por Campo e Fluxo/métodos , Reologia , Análise de Fourier , Poliestirenos/química , Padrões de Referência , Fatores de Tempo
16.
Biomed Eng Online ; 20(1): 23, 2021 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-33632226

RESUMO

BACKGROUND: Precise visualization of meshes and their position would greatly aid in mesh shrinkage evaluation, hernia recurrence risk assessment, and the preoperative planning of salvage repair. Lightweight (LW) meshes are able to preserve abdominal wall compliance by generating less post-implantation fibrosis and rigidity. However, conventional 3D imaging techniques such as computed tomography (CT) and magnetic resonance imaging (MRI) cannot visualize the LW meshes. Patients sometimes have to undergo a second-look operation for visualizing the mesh implants. The goal of this work is to investigate the potential advantages of Automated 3D breast ultrasound (ABUS) pore texture analysis for implanted LW hernia mesh identification. METHODS: In vitro, the appearances of four different flat meshes in both ABUS and 2D hand-held ultrasound (HHUS) images were evaluated and compared. In vivo, pore texture patterns of 87 hernia regions were analyzed both in ABUS images and their corresponding HHUS images. RESULTS: In vitro studies, the imaging results of ABUS for implanted LW meshes are much more visualized and effective in comparison to HHUS. In vivo, the inter-class distance of 40 texture features was calculated. The texture features of 2D sectional plans (axial and sagittal plane) have no significant contribution to implanted LW mesh identification. Significant contribution was observed in coronal plane. However, since the mesh may have spatial variation such as shrinkage after implantation surgery, the inter-class distance of 3D coronal plane pore texture features are bigger than 2D coronal plane, so the contribution of 3D coronal plane pore texture features are more valuable than 2D coronal plane for implanted LW mesh identification. The use of 3D pore texture features significantly improved the robustness of the identification method in distinguishing between LW mesh and fascia. CONCLUSIONS: An innovative new ABUS provides additional pore texture visualization, by separating the LW mesh from the fascia tissues. Therefore, ABUS has the potential to provides more accurate features to characterize pore texture patterns, and ultimately provide more accurate measures for implanted LW mesh identification.


Assuntos
Parede Abdominal/diagnóstico por imagem , Hérnia/diagnóstico por imagem , Processamento de Imagem Assistida por Computador/métodos , Reconhecimento Automatizado de Padrão , Telas Cirúrgicas , Adulto , Idoso , Feminino , Análise de Fourier , Hérnia/terapia , Humanos , Imageamento Tridimensional , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Próteses e Implantes , Ultrassonografia
17.
Spectrochim Acta A Mol Biomol Spectrosc ; 252: 119477, 2021 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-33545509

RESUMO

Fast, sensitive, and noninvasive techniques are needed for better health care management, particularly when traditional biopsies could be replaced with appropriate analyses of body fluids, such as saliva. Here is presented a proof-of-concept study, which aims to test a recently developed saliva samples preparation method, for oral and oropharyngeal cancer diagnosis, using micro-Raman and Fourier transform infrared (FT-IR) spectroscopic techniques. The detected biomarker bands and the cancer classification rates are compared and discussed. Saliva samples were collected from healthy donors and pathologically confirmed oral and oropharyngeal cancer patients. Principal components analysis (PCA) and principal components analysis-linear discriminant analysis (PCA-LDA) chemometric methods were applied to build discrimination models for the test and control groups. Based on the differences between salivary spectra of healthy and cancer patients, several biomarker bands were identified. Noteworthy, a significant vibrational biomarker band at 2064 cm-1, assigned to thiocyanate, was observed in both the FT-IR and Raman data-set. Other cancer characteristic Raman bands were 754 cm-1 (tryptophan), 530 and 927 cm-1 (lysozyme), 1001 cm-1 (phenylalanine), while the FT-IR biomarker band was located at 1075 cm-1 (phosphodiester bonds stretching in DNA, RNA). The oral and oropharyngeal cancer was classified with an accuracy of 90% based on the micro-Raman data and 82% based on the FT-IR data set, respectively. The study showed that oral and oropharyngeal cancer can be differentiated from control saliva samples based on their respective micro-Raman and FT-IR spectral signatures, due to the biomolecular modifications induced by the disease.


Assuntos
Neoplasias Orofaríngeas , Saliva , Espectroscopia de Infravermelho com Transformada de Fourier , Análise Discriminante , Análise de Fourier , Humanos , Neoplasias Orofaríngeas/diagnóstico , Análise Espectral Raman
18.
AJR Am J Roentgenol ; 216(3): 781-790, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33474982

RESUMO

OBJECTIVE. The purpose of this article is to review currently available and emerging techniques for pediatric lung MRI for general radiologists. CONCLUSION. MRI is a radiation-free alternative to CT, and clearly understanding the strengths and limitations of established and emerging techniques of pediatric lung MRI can allow practitioners to select and combine the optimal techniques, apply them in clinical practice, and potentially improve early diagnostic accuracy and patient management.


Assuntos
Pneumopatias/diagnóstico por imagem , Pulmão/diagnóstico por imagem , Imageamento por Ressonância Magnética/métodos , Adolescente , Artefatos , Suspensão da Respiração , Criança , Pré-Escolar , Fibrose Cística/diagnóstico por imagem , Feminino , Análise de Fourier , Humanos , Lactente , Neoplasias Pulmonares/diagnóstico por imagem , Neoplasias Pulmonares/secundário , Imageamento por Ressonância Magnética/tendências , Masculino , Atelectasia Pulmonar/prevenção & controle , Rabdomiossarcoma/diagnóstico por imagem , Rabdomiossarcoma/secundário
19.
Spectrochim Acta A Mol Biomol Spectrosc ; 251: 119426, 2021 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-33485242

RESUMO

A method is described using rapid and sensitive Fourier transform near-infrared spectroscopy combined with Gas Chromatograpy internal standard method detection for the simultaneous identification and determination of three bioactive compounds in Amomum villosum samples. Partial least squares regression is selected as the analysis type and multiplicative scatter correction, second derivative, and SNV were adopted for the spectral pretreatment. The correlation coefficients (R) of the calibration models were above 0.95 and the root mean square error of predictions were under 0.8. The developed models were applied to unknown samples with satisfantory results. The established method was validated and can be applied to the intrinsic quality control of Amomum villosum.


Assuntos
Amomum , Calibragem , Análise de Fourier , Análise dos Mínimos Quadrados , Espectroscopia de Infravermelho com Transformada de Fourier , Espectroscopia de Luz Próxima ao Infravermelho
20.
J Biomech ; 117: 110247, 2021 03 05.
Artigo em Inglês | MEDLINE | ID: mdl-33493712

RESUMO

Osteomalacia is a pathological bone condition consisting in a deficient primary mineralization of the matrix, leading to an accumulation of osteoid tissue and reduced bone mechanical strength. The amounts, properties and organization of bone constituents at tissue level, are known to influence its mechanical properties. It is then important to investigate the relationship between mechanical behavior and tissue composition at this scale in order to provide a better understanding of bone fragility mechanisms associates with this pathology. Our purpose was to analyze the links between ultra-structural properties and the mechanical behavior of this pathological bone tissue (osteomalacia) at tissue level (mineral and osteoid separately, or global). Four bone biopsies were taken from patients with osteomalacia, and subsequently embedded, sectioned, and polished. Then nanoindentation tests were performed to determine local elastic modulus E, contact hardness Hc and true hardness H for both mineralized and organic bone phases and for the global bone. The creep of the bone was also studied using a special indentation procedure in order to assess visco-elasto-plastic (creep) bone behavior. This allowed a detailed study of the rheological models adapted to the bone and to calculate the parameters associated to a Burgers model. Ultra-structural parameters were measured by Fourier Transform InfraRed Microspectroscopy (FTIRM) on the same position as the indents. The use of rheological models confirmed a significant contribution from the organic phase on the viscous character of bone tissue. The elastic E and the elasto-plastic Hc deformation were correlated to both collagen maturity and Mineral/Matrix. The pure plastic deformation H was only correlated to the mineral phase. Our data show that mineral phase greatly affects mechanical variables (moduli and viscosities) and that organic phase (as illustrated in osteoid tissue) may play an important role in the creep behavior of bone. In conclusion, this study brings mechanical and physicochemical values for osteoid and mineral phases.


Assuntos
Osteomalacia , Osso e Ossos , Análise de Fourier , Dureza , Humanos , Viscosidade
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