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1.
Spectrochim Acta A Mol Biomol Spectrosc ; 244: 118825, 2021 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-32866803

RESUMO

Novel antiviral active molecule 2- [(4,6-diaminopyrimidin-2-yl)sulfanyl]-N-(4-fluoro- phenyl)acetamide has been synthesised and characterized by FT-IR and FT-Raman spectra. The equilibrium geometry, natural bond orbital calculations and vibrational assignments have been carried out using density functional B3LYP method with the 6-311G++(d,p) basis set. The complete vibrational assignments for all the vibrational modes have been supported by normal coordinate analysis, force constants and potential energy distributions. A detailed analysis of the intermolecular interactions has been performed based on the Hirshfeld surfaces. Drug likeness has been carried out based on Lipinski's rule and the absorption, distribution, metabolism, excretion and toxicity of the title molecule has been calculated. Antiviral potency of 2- [(4,6-diaminopyrimidin-2-yl)sulfanyl]-N-(4-fluoro-phenyl) acetamide has been investigated by docking against SARS-CoV-2 protein. The optimized geometry shows near-planarity between the phenyl ring and the pyrimidine ring. Differences in the geometries due to the substitution of the most electronegative fluorine atom and intermolecular contacts due to amino pyrimidine were analyzed. NBO analysis reveals the formation of two strong stable hydrogen bonded N-H···N intermolecular interactions and weak intramolecular interactions C-H···O and N-H···O. The Hirshfeld surfaces and consequently the 2D-fingerprint confirm the nature of intermolecular interactions and their quantitative contributions towards the crystal packing. The red shift in N-H stretching frequency exposed from IR substantiate the formation of N-H···N intermolecular hydrogen bond. Drug likeness and absorption, distribution, metabolism, excretion and toxicity properties analysis gives an idea about the pharmacokinetic properties of the title molecule. The binding energy -8.7 kcal/mol of the nonbonding interaction present a clear view that 2- [(4,6-diaminopyrimidin-2-yl)sulfanyl]-N-(4-fluoro- phenyl) acetamide can irreversibly interact with SARS-CoV-2 protease.


Assuntos
Antivirais/química , Betacoronavirus/efeitos dos fármacos , Infecções por Coronavirus/tratamento farmacológico , Pandemias , Pneumonia Viral/tratamento farmacológico , Inibidores de Proteases/química , Proteínas não Estruturais Virais/antagonistas & inibidores , Antivirais/farmacocinética , Betacoronavirus/enzimologia , Cristalografia por Raios X , Cisteína Endopeptidases , Humanos , Modelos Moleculares , Simulação de Acoplamento Molecular , Estrutura Molecular , Dinâmica não Linear , Inibidores de Proteases/farmacocinética , Conformação Proteica , Teoria Quântica , Espectroscopia de Infravermelho com Transformada de Fourier , Análise Espectral Raman , Termodinâmica , Vibração
2.
Sci Total Environ ; 751: 141476, 2021 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-32871309

RESUMO

BACKGROUND: More women in reproductive ages are entering occupations where exposure to whole body vibrations (WBV) is common (e.g. in transportation and construction). Previous studies based on self-assessed exposure suggest increased risks of adverse birth outcomes, but it is unclear at what exposure levels and if the current exposure guidelines are appropriate during pregnancy. OBJECTIVES: To investigate whether occupational WBV-exposure increases the risk of preterm birth, low birth weight, and/or small-for-gestational age, in a large, nationwide, prospective, cohort study. DESIGN: The Fetal Air Pollution Exposure cohort (FAIR) was formed by merging data from multiple, national registers, and the present study includes singletons born 1994-2014 to working women in Sweden (n = 1,091,080 births). WBV-exposure was assessed quantitatively using a job-exposure matrix based on measurements, and calculated odds ratios were adjusted for potential confounders such as smoking and BMI, and other occupational exposures like noise, combustion particles, and physically and psychologically strenuous work. Data on absence from work (full-/part time, sick leave, parental leave, etc.) was also used. RESULTS: Exposure to WBV during pregnancy, among women with low absence from work (n = 476,419), was associated with an increased risk of preterm birth, below the occupational exposure limit (1.15 m/s2). Compared to unexposed mothers, the OR was 1.38 (95% CI: 1.05, 1.83) for exposure ≥0.5 m/s2, corresponding to an increase from 47/1000 cases to 65/1000 cases. No increased risk was found for small-for-gestational age. CONCLUSIONS: Exposure to WBV was associated with an increased risk of preterm birth. The results suggest that the current permissible exposure and action levels for WBV-exposure do not adequately protect pregnant women with continuous exposure.


Assuntos
Exposição Ocupacional , Nascimento Prematuro , Estudos de Coortes , Feminino , Humanos , Recém-Nascido , Recém-Nascido Pequeno para a Idade Gestacional , Exposição Ocupacional/efeitos adversos , Gravidez , Resultado da Gravidez/epidemiologia , Nascimento Prematuro/epidemiologia , Estudos Prospectivos , Suécia/epidemiologia , Vibração/efeitos adversos
3.
Orthod Fr ; 91(1-2): 83-91, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-33146137

RESUMO

Mandibular proprioception would influence postural control. The development of spatial references are governed by the same afferences. This work aims to clarify the role of mandibular proprioception, implicated in postural and spatial dysfunctions, in the control of cephalic posture and spatial repositories. 24 subjects received a vibration of the masseter and temporal muscles. Measurements of head position (HP) (video), subjective visual vertical (SVV) and line bisection (LB) were obtained with and without vibration. Without vibration, HP (0.31 ° ± 1.76 °) was negatively correlated with SVV (+ 0.23 ° ± 0.62 °, r22 = -0.44, p = 0.033); with vibration, HP on the opposite side to the stimulated muscle (t23 = 2.77, p = 0.011). There is a correlation between LB and SVV. Without vibration, the Müller effect is found for SVV. The pseudo-negligence is not found. With vibration, the error of the HP and the SVV go in the same direction. No effects on the LB. Conclusion: Beyond local responses, the vibration can evoke global and oriented responses.


Assuntos
Mandíbula , Propriocepção , Humanos , Postura , Vibração
5.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 3779-3782, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018824

RESUMO

In this paper, a perception-empathy biofeedback (PEBF) system is proposed that supplements the foot pressure status of a paralyzed foot with a wearable vibrotactile biofeedback (BF) vest to the back. Improvements in the ankle dorsiflexion and push-off movement in the swing phase and pre-swing phase, respectively, can be expected after using the proposed system. However, the results of the 3 week pilot clinical tests suggest that significant improvement is only observed for the push-off movement. It is assumed that the attention required to recognize the BF was beyond the ability of the patients. In this paper, a dual task (40 s walking and performing mental arithmetic at the same time) was conducted with the following conditions: no vibrations and providing BF to the lower back and the entire back. According to the results, the ankle joint angle of the paralyzed side at push-off under the entire back condition is statistically significant (p = 0.0780); however, there are no significant changes under the lower back condition (p = 0.4998). Moreover, the ankle joint angle of the paralyzed side at the initial contact is statistically significant with respect to the lower back condition (p = 0.0233) and shows a significant trend for the entire back condition (p = 0.0730). The results suggest that the limited attention capacity of hemiplegic patients fails to improve both dorsiflexion and push-off movements; moreover, ankle motion can be promoted if attention is concentrated on recognizing focalized vibratory feedback patterns.


Assuntos
Empatia , Vibração , Atenção , Biorretroalimentação Psicológica , Humanos , Caminhada
6.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 3897-3900, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018852

RESUMO

Understanding the joint encoding of multiple tactile stimulus features (e.g., spatial position, amplitude, and frequency of vibration) is a major goal of somatosensory neuroscience, and the development of experimental set-ups to probe joint encoding is important. We describe in detail a microcontroller-based, piezoelectric bender device for tactile experiments. The device comprises an Arduino Due microcontroller board with a 32-bit ARM Cortex-M3 RISC processor, and two 12-bit digital-to-analog converters, enabling precise, independent stimulation of adjacent epithelial points. Using laser doppler vibrometry, we developed a model of the benders' structural mechanics, which we implemented on the device. We used the device to delivered precise, reliable somatosensory stimulation in an experimental setting, recording electrophysiological responses in the peripheral nervous system of the Gisborne cockroach (Drymaplaneta semivitta) to sinusoidal vibration of tibial spines. We plotted tuning curves and derived bandwidths of multi-unit populations. We also stimulated rat facial vibrissae ex vivo. This microcontroller-based, low-cost, open-source system leverages a large developer community associated with Arduino, and may help speed advances in systems neuroscience.


Assuntos
Neurociências , Tato , Animais , Córtex Cerebral , Fenômenos Eletrofisiológicos , Ratos , Vibração
7.
Artigo em Inglês | MEDLINE | ID: mdl-33017920

RESUMO

Cardiography enables diagnostic and preventive care in hospitals and outpatient scenarios. However, most heart monitors do not distinguish the phases of the cardiac cycle. The transition between phases is indicated by the primary heart sounds. OBJECTIVE: Automatically identify the vibrations corresponding to both heart sounds. METHODS: Cardiac activity was monitored for 15 subjects while at rest, during exertion, and while performing static breath holds. The subjects consisted of 6 males and 9 females between the ages of 18-39 years with no known cardiorespiratory ailments. Motion corresponding to the heart sounds was identified using vibrational cardiography (VCG). The waveforms were processed to obtain quantities associated with their linear jerk and rotational kinetic energy. RESULTS: The ability to identity the first vibration was evaluated using the heart rate as a figure of merit. Its correlation with electrocardiography (ECG) measurements produced a r2 coefficient of 0.9887. The second vibration was compared with impedance cardiography (ICG) based on its delay from the ECG R-peak, and the fraction of the beat duration occupied by left ventricular ejection time. The comparisons produced r2 values of 0.251 and 0.2797, respectively. CONCLUSION: The vibrations corresponding to both primary heart sounds have the potential to be analyzed using VCG. SIGNIFICANCE: This study provides evidence of the feasibility of using VCG in identifying mechanical cardiovascular function. It facilitates non-invasive cardiac health monitoring in daily life.


Assuntos
Ruídos Cardíacos , Adolescente , Adulto , Cardiografia de Impedância , Eletrocardiografia , Feminino , Frequência Cardíaca , Humanos , Masculino , Vibração , Adulto Jovem
8.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 221-224, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33017969

RESUMO

Non-invasive health monitoring has the potential to improve the delivery and efficiency of medical treatment. OBJECTIVE: This study was aimed at developing a neural network to classify the lung volume state of a subject (i.e. high lung volume (HLV) or low lung volume (LLV), where the subject had fully inhaled or exhaled, respectively) by analyzing cardiac cycles extracted from vibrational cardiography (VCG) signals. METHODS: A total of 15619 cardiac cycles were recorded from 50 subjects, of which 9989 cycles were recorded in the HLV state and the remaining 5630 cycles were recorded in the LLV state. A 1D convolutional neural network (CNN) was employed to classify the lung volume state of these cardiac cycles. RESULTS: The CNN model was evaluated using a train/test split of 80/20 on the data. The developed model was able to correctly classify the lung volume state of 99.4% of the testing data. CONCLUSION: VCG cardiac cycles can be classified based on lung volume state using a CNN. SIGNIFICANCE: These results provide evidence of a correlation between VCG and respiration volume, which could inform further analysis into VCG-based cardio-respiratory monitoring.


Assuntos
Algoritmos , Redes Neurais de Computação , Coração/diagnóstico por imagem , Pulmão/diagnóstico por imagem , Vibração
9.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 2638-2641, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018548

RESUMO

Remote health monitoring is a widely discussed topic due to its potential to improve quality and delivery of medical treatment and the global increase in cardiovascular diseases. OBJECTIVE: Seismocardiography and Gyrocardiography have been shown to provide reliable heart rate information. A simple and efficient setup was developed for the monitoring of mechanical signals at the sternum. An algorithm based in autocorrelation was run on subjects with different orientations in order to detect heart rate. METHODS: Subjects performed several tests where both SCG and GCG were recorded using an inertial measurement unit, a Raspberry Pi and a BIOPAC acquisition system. A total of 2335 cardiac cycles were obtained from 5 subjects. Heart rate was determined on a per second basis and compared with an electrocardiography (ECG) reference by correlation coefficients. Ensemble averages were used to visualize differences in VCG morphology. RESULTS: Heart rate estimation obtained from VCG signals across all 5 subjects was referenced with ECG and achieved an r-squared correlation coefficient of 0.956 when supine and 0.975 when standing, compared to 0.965 across the entire dataset. CONCLUSION: Autocorrelated Differential Algorithm was able to successfully detect heart rate, regardless of orientation and posture. SIGNIFICANCE: Changes in orientation of the body during measurement introduce inaccuracies. This work shows that the algorithm is resistant to orientation and more adaptable to everyday life.


Assuntos
Eletrocardiografia , Vibração , Algoritmos , Coração , Frequência Cardíaca
10.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 3106-3109, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018662

RESUMO

Vibration exercise (VE) has been suggested for effective muscle training and conditioning. Surface electromyogram (EMG) is employed as a powerful tool for the analysis of VE. However, sharp peaks are observed in the EMG spectrum. The interpretation of these peaks is controversial, complicating the extraction of EMG parameters for VE analysis. The present study is therefore aiming at quantifying the relevance of these spectral peaks in EMG recording during VE. To this end, surface EMG was recorded on the biceps brachii during VE at different amplitudes and frequencies. The power percentage contained in the two narrow bands (±0.5 Hz) around the vibration frequency and its first harmonic (PPv) was calculated. The root mean square (RMS) value of the EMG was calculated with and without including the spectral peaks and then compared. The results show an average PPv value of 20.7 ± 7.9 % and a relative RMS difference (∆RMS) of 12.2 ± 3.8 %. In PPv and addition, RMS∆ seem to be influenced by vibration amplitude and frequency. Our results provide useful information for the analysis of VE and contribute to better understanding of the EMG spectral peaks.


Assuntos
Exercício Físico , Vibração , Eletromiografia , Humanos , Músculo Esquelético , Modalidades de Fisioterapia
11.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 4454-4457, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018983

RESUMO

This paper introduces a low-cost phantom system that simulates fetal movements (FMVs) for the first time. This vibration system can be used for testing wearable inertial sensors which detect FMVs from the abdominal wall. The system consists of a phantom abdomen, a linear stage with a stepper motor, a tactile transducer, and control circuits. The linear stage is used to generate mechanical vibrations which are transferred to the latex abdomen. A tactile transducer is implemented to add environmental noise to the system. The system is characterized and tested using a wireless sensor. The sensor recordings are analyzed using time-frequency analysis and the results are compared to real FMVs reported in the literature. Experiments are conducted to characterize the vibration range, frequency response, and noise generation of the system. It is shown that the system is effective in simulating the vibration of fetal movements, covering the full frequency and magnitude ranges of real FMV vibrations. The noise generation test shows that the system can effectively create scenarios with different signal-to-noise ratios for FMV detection. The system can facilitate the development of fetal movement monitoring systems and algorithms.


Assuntos
Movimento Fetal , Dispositivos Eletrônicos Vestíveis , Humanos , Modalidades de Fisioterapia , Transdutores , Vibração
12.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 5905-5908, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33019318

RESUMO

Early inter-hospital ambulance transport of premature babies is associated with more severe brain injury. The mechanism is unclear, but they are exposed to excessive noise and vibration. Smart-routing may help minimise these exposure levels and potentially improve outcomes.An app for Android smartphones was developed to collect vibration, noise and location data during ambulance journeys. Four smartphones, with the app installed, were provided to the local neonatal transport group to attach to their incubator trolleys. An example of route comparison was performed on the roads used between Nottingham City Hospital (NCH) and Leicester Royal Infirmary (LRI).Almost 1,700 journeys were recorded over the space of a year. 39 of these journeys travelled from NCH to LRI, comprising of 9 different routes. Analysis was performed on all recorded data which travelled along each road. For routes from NCH to LRI, the route with least vibration was also the quickest. Noise levels, however, were found to increase with vehicle speed. Ambulance drivers in the study did not tend to take the quickest, smoothest or quietest route.Android smartphones are a practical method of gathering information about the in-ambulance environment. Routes were found to vary in vibration, noise and speed, suggesting these could be minimised. The next step is to combine recorded and clinical data to try and define an ideal neonatal comfort metric which can then be fed into the routing. Roll-out of the app around the UK is also planned.Clinical relevance-Transferring preterm neonatal infants to specialist units lead to worse outcomes. By reducing the levels of vibration and noise the infants are exposed to during transport, we hope to improve outcomes.


Assuntos
Ambulâncias , Macas (Leitos) , Humanos , Lactente , Recém-Nascido de Baixo Peso , Recém-Nascido , Ruído , Vibração
13.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 6086-6089, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33019359

RESUMO

Premature infants or neonates in need of advanced clinical care must be transported to specialized hospitals. Past studies have examined vibrations experienced by patients during transport; however, multiple confounding factors limit the utility of on-road data. Hence, the development of a standardized test environment is warranted. The overall purpose of this project is to characterize vibrations during neonatal patient transport and develop mitigation strategies to reduce exposure. This paper focusses on the development of a laboratory test environment and procedure that enables studying the equipment vibration in a comprehensive and repeatable manner. For the first time, a complete neonatal patient transport system, including a stretcher, has been mounted on an industrial shaker. Results largely validate the system's ability to simulate on-road vibrations with high repeatability.


Assuntos
Hospitais Especializados , Vibração , Humanos , Lactente , Recém-Nascido
14.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 4600-4603, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33019018

RESUMO

Postural instability assessment is an important tool in fall risk analysis and for timely intervention of falls to reduce or prevent fall injuries. Traditionally fall risk is measured though postural sway assessment and is collected through forceplates by mapping Center of Pressure (COP) excursions or using motion analysis camera system for marker sway trajectories. However, both of these systems are expensive and lack portability to their usage in clinical environments. In this study, we developed a novel wearable low-cost MEMS inertial sensor and validated its usage for human postural sway assessment in standing posture with eyes open/closed, vibration/no vibration, and proprioception /low proprioception conditions. The two objectives of this study were: 1) To develop and validate an Inertial Measurement Unit (IMU) for sway analysis 2) To determine the feasibility of the system in detecting human postural imbalances such as reduced proprioception or presence of stochastic resonance induced through subthreshold vibrations on the feet. The novel IMU was tested for sway against infra-red marker on a specialized platform with 4-degrees of freedom. Many parameters of postural sway such as sway velocity, Root Mean Square (RMS), and sway path length could successfully detect subtle postural changes due to varying proprioceptive and sub-threshold vibration conditions. We found agreement in sway signal determinism from the two methods.Clinical Relevance- This wearable sensor technology has potential to determine balance in reliable, easy and accurate way in clinical environments.


Assuntos
Equilíbrio Postural , Dispositivos Eletrônicos Vestíveis , Humanos , Postura , Propriocepção , Vibração
15.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 4909-4912, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33019089

RESUMO

Vibro-tactile feedback offers a complementary augmentation cue for motor guidance and training. Motivated by the needs of prosthetic vision rehabilitation, we explore the use of the cylindrical forearm surface to deliver arm guidance cues via vibro-tactile stimulation. We present 'VibroSleeve', a novel wearable arm motion guidance aid made up of 4x4 arrangement of vibration coin motors embedded within an elastic sleeve for delivering vibro-tactile patterns to the forearm. In this paper, we present the concept and design of VibroSleeve, along with results of preliminary evaluation. We outline key insights gained into the perceptual aspects of calibration and usable intensity bandwidth critical for reliable interpretation of encoded information. Our results demonstrate feasibility of the approach, and provide foundations for future work on developing the sleeve as a rehabilitation aid for guiding the arm towards visually perceived targets.


Assuntos
Braço , Dispositivos Eletrônicos Vestíveis , Retroalimentação , Tato , Vibração
17.
PLoS One ; 15(10): e0237733, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33027294

RESUMO

Measuring vibration perception threshold (VPT) accurately classifies and quantifies the severity of loss of vibration perception. A biothesiometer (Bio-thesiometer®; Bio Medical Instrument Co, Ohio, USA) appears to be the most suitable tool to determine VPT due to its low inter-rater variability and low occurence of adaption to the sensation. Different VPT values for a biothesiometer have been described, however, specification on age, height and different measurement locations is currently lacking. The objective of our study was to identify determinants of vibration perception in non-diabetic subjects, in order to provide individualized normal values of VPTs for clinical practice. Measurements of the vibration perception were performed on the big toes, insteps, lateral malleoli, and wrists. A total of 205 healthy subjects were included (108 (52.7%) males) with a median [interquartile range] age of 59 [51;64] (range 21-80) years. Mean height was 174.45 ± 9.20 cm and mean weight was 82.94 ± 14.84 kg, resulting in a mean BMI of 27.19 ± 4.00 kg/m2. In stepwise forward linear regression analyses, age (st. ß = 0.51, p < 0.001) and height (st. ß = 0.43, p < 0.001) were found to be the independent unmodifiable determinants of the VPT at the big toe. Regression coefficients for quantiles of the determinants age and height were incorporated in the corresponding regression equations. This study provides equations to calculate age- and height-specific normal values for VPT that can be used in clinical practice and in large research studies.


Assuntos
Limiar Sensorial/fisiologia , Vibração , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Neuropatias Diabéticas/fisiopatologia , Feminino , Voluntários Saudáveis , Humanos , Modelos Lineares , Masculino , Pessoa de Meia-Idade , Valores de Referência , Adulto Jovem
18.
Sheng Li Xue Bao ; 72(5): 643-650, 2020 Oct 25.
Artigo em Chinês | MEDLINE | ID: mdl-33106834

RESUMO

This paper discusses the short-term memory of vibro-tactile perception of human fingertips. By using a self-developed vibro-tactile expression device, a recall experiment was firstly carried out among 20 subjects aged 20-30 (10 males and 10 females) to discover the memory span about the vibro-tactile perception of human fingertips. Within this memory span, a cognitive experiment analyzing the recognition accuracy and the reaction time was carried out. The results showed: (1) The vibro-tactile memory span of human fingertip is 4 ± 1; (2) The vibro-tactile memory span increases as the discrete intensity between vibration stimuli increases; (3) Too long or too short vibration duration will reduce the vibro-tactile memory span, and the optimal vibration duration for men is 400 ms, for women is 300 ms; (4) The more the number of vibration stimuli is perceived by the human fingertip, the lower the recognition accuracy and the longer the reaction time it needs; (5) Compared with the vibration stimuli in disorder, people are more likely to remember the vibration stimuli in increasing/decreasing order; (6) The information extraction mechanism of the short-term memory about fingertip vibro-tactile perception bases a point to point scanning process among these stimuli. These results help to understand the human fingertip tactile characteristics and provide a physiological basis for the study of tactile feedback technologies.


Assuntos
Memória de Curto Prazo , Percepção do Tato , Adulto , Feminino , Dedos , Humanos , Masculino , Tato , Vibração , Adulto Jovem
19.
Nat Commun ; 11(1): 4569, 2020 09 11.
Artigo em Inglês | MEDLINE | ID: mdl-32917892

RESUMO

Eumelanin is a brown-black biological pigment with sunscreen and radical scavenging functions important to numerous organisms. Eumelanin is also a promising redox-active material for energy conversion and storage, but the chemical structures present in this heterogeneous pigment remain unknown, limiting understanding of the properties of its light-responsive subunits. Here, we introduce an ultrafast vibrational fingerprinting approach for probing the structure and interactions of chromophores in heterogeneous materials like eumelanin. Specifically, transient vibrational spectra in the double-bond stretching region are recorded for subsets of electronic chromophores photoselected by an ultrafast excitation pulse tuned through the UV-visible spectrum. All subsets show a common vibrational fingerprint, indicating that the diverse electronic absorbers in eumelanin, regardless of transition energy, contain the same distribution of IR-active functional groups. Aggregation of chromophores diverse in oxidation state is the key structural property underlying the universal, ultrafast deactivation behavior of eumelanin in response to photoexcitation with any wavelength.


Assuntos
Melaninas/química , Vibração , Oxirredução , Espectrofotometria Infravermelho/métodos , Protetores Solares
20.
PLoS One ; 15(9): e0238051, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32915796

RESUMO

The aim of this study was to compare the effects of vibration (Vib versus noVib) during a maximal graded cycling exercise on hormonal response, precisely on cortisol (C) and testosterone (T). Twelve active males (25 ± 5yrs; 181 ± 5cm; 80.7 ± 11.1kg) randomly performed two maximal incremental cycling tests on two separate days and at the same time of the day (09:00). The protocol consisted of incremental steps of 3 min duration performed on a PowerBIKETM that induces vibration cycling. The study was a repeated measures design and participants performed the test with and without vibration. Gas exchange and heart rate (HR) were continuously assessed and blood lactate (Bla) was recorded at the end of each incremental stage. Saliva samples were collected before and immediately after the test, and analysed for (C) and (T). The results show that C and T increased in both cycling conditions; however, the C's magnitude of change was significantly higher by 83% after Vib cycling in comparison to the no Vib (p = 0.014), whereas the T's magnitude of change were not statistically different between trials (p = 0.715). Vibration induced a decrease of the T/C ratio (p = 0.046) but no significant changes were observed following noVib (p = 0.476). As a conclusion, the investigation suggests that adding mechanical vibration to cycling may potentiate a catabolic exercise-induced state, which could have potential clinical implications in rehabilitation and injury treatment. Sport experts should take this message home to carefully plan the recovery process and time during training and competitions.


Assuntos
Ciclismo , Saliva/metabolismo , Vibração , Adolescente , Adulto , Frequência Cardíaca , Humanos , Hidrocortisona/análise , Ácido Láctico/sangue , Masculino , Consumo de Oxigênio , Testosterona/análise , Adulto Jovem
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