Valentina Vassilenko

• Assistant Professor
• Professor (Assistant) at Universidade NOVA de Lisboa

This paper addresses the challenge posed by the size of certain objects that do not conform to the constraints of microscope‐coupled Raman spectrometers, making sample collection impossible due to their inherent value or nature. Specifically, materials like hydroxyapatite‐based substances used in artistic and ornamental carvings, such as bone or iv...

Providing employees with proper work conditions should be one of the main concerns of any employer. Even so, in many cases, work shifts chronically expose the workers to a wide range of potentially harmful compounds, such as ammonia. Ammonia has been present in the composition of products commonly used in a wide range of industries, namely producti...

One of the main reasons for the degradation of working conditions is the lack of air quality. It is known that indoor air contaminants pose a risk to both the human organism and the environment, which constitutes a challenge for employers and major industries. A car factory painting line is an evident example of a work location in which the employe...

The field of organic-borne biomarkers has been gaining relevance due to its suitability for diagnosing pathologies and health conditions in a rapid, accurate, non-invasive, painless and low-cost way. Due to the lack of analytical techniques with features capable of analysing such a complex matrix as the human breath, the academic community has focu...

The assessment of volatile breath biomarkers has been targeted with a lot of interest by the scientific and medical communities during the past decades due to their suitability for an accurate, painless, non-invasive, and rapid diagnosis of health states and pathological conditions. This paper reviews the most relevant bibliographic sources aiming...

O uso de corpos humanos para ensino dos futuros profissionais da saúde, é imprescindível para seu aprendizado. Assim, anatomistas conseguem fixar, sanitizar e prolongar o processo de decomposição. O formol é o químico mais antigo utilizado nesse procedimento e de baixo custo. No entanto, a Agência Internacional de Pesquisa sobre o Câncer comprovou...

The employment of advanced analytical techniques and instrumentation enables the tracing of volatile organic compounds (VOCs) in vestigial concentrations (ppbv-pptv range) for several emerging applications, such as the research of disease biomarkers in exhaled air, the detection of metabolites in several biological processes, and the detection of p...

Proper working conditions must be one of the employers’ main concerns in any type of company but particularly in work locations where the employees are chronically exposed to hazardous compounds, like factories and production lines. Regarding this challenge, the present research addresses the mapping of a car factory painting line to possibly toxic...

Contemporary life is mostly spent in indoor spaces like private houses, workplaces, vehicles and public facilities. Nonetheless, the air quality in these closed environments is often poor which leads to people being exposed to a vast range of toxic and hazardous compounds. Volatile organic compounds (VOCs) are among the main factors responsible for...

Normal and abnormal/pathological status of physiological processes in the human organism can be characterized through Volatile Organic Compounds (VOCs) emitted in breath. Recently, a wide range of volatile analytes has risen as biomarkers. These compounds have been addressed in the scientific and medical communities as an extremely valuable metabol...

The inclusion of seaweeds in daily-consumption food is a worthy-of-attention challenge due to their high nutritional value and potential health benefits. In this way, their composition, organoleptic profile, and toxicity must be assessed. This work focuses on studying the volatile organic compounds (VOCs) emitted by three edible seaweeds, Grateloup...

Volatile organic compounds (VOCs) can be extremely toxic and hazardous to expose humans in both indoor and outdoor environments; thus, their detection, correct identification, and accurate quantification are relevant and demanding tasks that need to be addressed. Fortunately, several known analytical techniques allow the qualitative and quantitativ...

Ion Mobility Spectrometry (IMS) has gained relevance in the field of analytical techniques over the past decades. If compared with well-established techniques like mass spectrometry or infrared spectroscopy, IMS is considerably less developed or employed in specific fields but presents promising results and a substantial margin for improvements. It...

Industrial environments are frequently composed of potentially toxic and hazardous compounds. Volatile organic compounds (VOCs) are one of the most concerning categories of analytes commonly existent in the indoor air of factories’ facilities. The sources of VOCs in the industrial context are abundant and a vast range of human health conditions and...

Heart Rate Variability (HRV) is a biomarker that can be obtained non-invasively from the electrocardiogram (ECG) or the photoplethysmogram (PPG) fiducial points. However, the accuracy of HRV can be compromised by the presence of artifacts. In the herein presented work, a Simulink® model with a deep learning component was studied for overly noisy PP...

Society’s concerns about the citizens’ exposure to possibly dangerous environments have recently risen; nevertheless, the assessment of indoor air quality still represents a major contemporary challenge. The volatile organic compounds (VOCs) are among the main factors responsible for deteriorating air quality conditions. These analytes are very com...

Several modern human cadaveric fixation methods are subject to permanent evaluation. Formaldehyde is the oldest and still the most widely used method of embalming. However, the International Agency for Research on Cancer has proven its high carcinogenic potential and its use was banned, with the recommendation of research for better alternatives in...

Heart Rate Variability (HRV) evaluates the autonomic nervous system regulation and can be used as a monitoring tool in conditions such as cardiovascular diseases, neuropathies and sleep staging. It can be extracted from the electrocardiogram (ECG) and the photoplethysmogram (PPG) signals. Typically, the HRV is obtained from the ECG processing. Bein...

Background and aim Evaluating the protective effect in human enamel of a fluorinated varnish after enduring a citric acid erosive challenge. Methods An in vitro model was developed considering the intraoral environment, human saliva and acid erosive procedures. The evaluation of the enamel specimens was undertaken through the direct analysis of en...

The Heart Rate Variability (HRV) signal computation relies on fiducial points typically obtained from the electrocardiogram (ECG) or the photoplethysmogram (PPG). Generally, these fiducial points correspond to the peaks of the ECG or PPG. Consequently, the HRV quality depends on the fiducial points detection accuracy. In a previous work, this subje...

This work explores the suitability of data treatment methodologies for Raman spectra of teeth using multivariate analysis methods. Raman spectra were measured in our laboratory and obtained from control enamel samples and samples with a protective treatment before and after an erosive attack. Three different approaches for data treatment were under...

Photoplethysmography (PPG) is widely used in wearable devices due to its conveniency and cost-effective nature. From this signal, several biomarkers can be collected, such as heart and respiration rate. For the usual acquisition scenarios, PPG is an artefact-ridden signal, which mandates the need for the designated classification algorithms to be a...

Alvarez waves are local rhythmic contractions of the myometrium with high frequency and low intensity. They can be detected using internal or external tocography and electrohysterography. Some researchers correlate these small contractions with the initiation of labor, since they have been described as a pattern representing the uterine response to...

Breath analysis is an expanding scientific field with great potential for creating personalized and non-invasive health screening and diagnostics techniques. However, the wide range of contradictory results in breath analysis is explained by the lack of an optimal standard procedure for selective breath sampling. Recently we developed novel instrum...

Several cadaveric fixation methods are used to keep human bodies preserved in the best possible way. According Healy et al (1), the formaldehyde is the oldest and most effective and still the most widely used method of embalming, which allow the preservation of macroscopic and microscopic features. However, the International Agency for Research on...

Infrared thermal imaging is a non-destructive, non-invasive technique that has shown to be effective in the detection and pre-clinical diagnosis of a variety of disorders. Nowadays, some medical applications have already been successfully implemented in pre-clinic diagnostics using thermography based on AI algorithms to support decision-based medic...

Stroke is a significant affliction that can affect people with varying degrees of severity. One of the most common consequences of stroke is the impairment of the muscular motor function to some degree with two-thirds of the patients being affected by upper-limb paralysis. For those cases, the most effective forms of regaining muscular motor functi...

Medical diagnosis research is driven into the development of non-invasive diagnosis devices centered in fast and precise analytical tools and instrumentation. This led to Volatile Organic Compounds (VOCs) being identified as metabolomics biomarkers for several diseases, including respiratory infections, cancer and even COVID 19 non-invasive test. W...

The pulse signal obtained non-invasively through an oscillometric method can accurately measure the Cardio-Ankle Vascular Index (CAVI) and Pulse Wave Velocity (PWV), two valuable physiological markers of arterial stiffness and cardiovascular health. The VOPITB device is designed to obtain these markers whose accuracy heavily depends on the correctn...

Raman spectroscopy is nowadays regarded as a practical optical method and non-destructive photonic tool, which can be applied in several biomedical fields for analyzing the molecular composition. This technique is considered appropriate for human dental tissues characterization, from caries detection to evaluation of demineralization caused by acid...

Uterine contractions’ monitoring has been pointed out as an important tool that may be useful in the preterm risk assessment, term birth estimation and uterine physiology investigation. The multichannel EHG provides a mapping of the myometrium electrical activity projection on the selected channels, providing a wealth of information, including pace...

Electrohysterography (EHG) is a promising technique for pregnancy monitoring and preterm risk evaluation. It allows for uterine contraction monitoring as early as the 20th gestational week, and it is a non-invasive technique based on recording the electric signal of the uterine muscle activity from electrodes located in the abdominal surface. In th...

The uterine electromyogram, also named Electrohysterogram (EHG), is a non-invasive technique that has been used for pregnancy and labour monitoring as well as for research work on uterine physiology. This technique is well established in this field. There is however a vast unexplored potential in the EHG that is currently the subject of interdiscip...

Modern work environment is changing from classic physiological to more psychological workloads. The capability to monitor biochemical processes within the human body positions breath analysis as a promising method to non-invasively and quickly detect mental stress. The present work aims to identify psychological stress biomarkers and breath profile...

Cardiovascular diseases remain the leading cause of morbidity, mortality, early disability and growing health costs worldwide. The difficulty for monitoring the evolution of cardiovascular related diseases can be, partially, attributed to the lack of appropriate indicators for arterial injury and cardiac disfunction during routine clinical practice...

Medical infrared thermal imaging techniques can provide the high-quality images for monitoring and pre-clinical diagnostic of the diseases by showing the thermal abnormalities available in the body. Its biggest advantage is non-contact, non-invasive and very fast way of use. However, the incorrect interpretation of the thermal images via simple obs...

Ion Mobility Spectrometry with a coupled Gas Chromatography (GC-IMS) pre-separation is an analytical technique suitable for detection of volatile organic compounds (VOCs) in complex sample matrices (indoor & outdoor air, breath samples, food, beverages, microbial cultures, etc.). Its outstanding sensitivity allows in-situ analysis of a very large r...

Air Quality research is a trending topic that has received increasing attention from scientific community around the globe. Due to the high relevance of recent discoveries in areas like medicine or chemistry, analytical techniques with high sensitivity and selectivity play a crucial role in the characterization of the ambient air composition. This...

Sigma Delta based biomedical acquisition systems are popular amongst the possible hardware architectures developed for this purpose. It allows for the creation of high-resolution low power and cost-effective universal systems, where oversampling is used with the advantage of the associated simplified anti-alias filter design. However, spurious idle...

Cardiovascular (CV) diseases are leading cause of mortality and arterial stiffness is a very important risk marker. It can be obtained by non-invasive measurements of carotid-femoral pulse wave velocity (cfPWV), recommended as a gold-standard marker of CV risk by European Society of Cardiology (ESC). Previous works proved that arterial stiffness’s...

Since 1960 the technological evolution in dentistry have contributed to a greater demand for dental care. The success of dental implantology depends from several factors, one of which is the health of the gingiva microcirculation status. Due to the dental implant location, direct monitoring of the health of the gingiva is a complex task requiring s...

Aging often results in the appearance of sarcopenia, which is characterized by loss of muscle mass and strength. The incidence of sarcopenia in the elderly is a quite common and leads to weakness and disability, as well as a lower quality of life, also assuming a high social and economic impact. One previous study has shown an independent negative...

The knowledge about the required quantity of blood to irrigate an angiosome is important on ischemia (disruption on blood perfusion) prediction, diagnosis and treatment. An angiosome (or flap) is an anatomic unity (or flap) of tissue, it is constituted by skin, subcutaneous tissue and muscle, it is irrigated by an artery and drain by specific veins...

Process of eye tomogram obtaining by means of optical coherent tomography is studied.Stages of idiopathic macula holes formation in the process of eye grounds diagnostics are considered. Main stages of retina pathology progression are determined: Fuzzy logic units for obtaining reliable conclusions regarding the result of diagnosis are developed. B...

The main aim of this work was to study the usefulness of human β-defensins 2 (BD-2) and 3 (BD-3), which are part of the innate immune system, in the treatment of infected ischemic skin flaps. We investigated the effect of transducing rat ischemic skin flaps with lentiviral vectors encoding human BD-2, BD-3, or both BD-2 and BD-3, to increase flap s...

Recognition of gestures is an actual and important problem. This technology can be applied in various fields of human activity: management of computers and household appliances, creating a natural human-machine interfaces for the deaf, the manipulation of three-dimensional models of objects, virtual reality applications, management of quadrocopters...

Cardiovascular (CV) diseases are the leading cause of mortality, and arterial stiffness is a well-known determinant CV risk factor, which can be evaluated by the measurements of carotid-femoral pulse wave velocity (cfPWV), recently proposed as a gold-standard marker of CV risk. Previous studies have confirmed arterial stiffness’s increase with agei...

Preeclampsia affects 2% of pregnant women and is one of the main causes of prenatal maternal mortality and morbidity. Recent studies with two-dimensional echocardiography have shown that PE is characterized by a marked reduction on maternal cardiac output and increased peripheral resistance. However, studies on the maternal hemodynamic adaptation d...

Preeclampsia (PE) affects pregnancy, being one of the main causes of prenatal maternal mortality and morbidity(1). Recent studies show that PE is characterized by a significant reduction on maternal cardiac output and increased peripheral resistance. However, studies on the maternal hemodynamic adaptation during PE and the available information abo...

The aim of this study was to evaluate in the Wistar rat the efficacy of various autologous nerve conduits with various forms of blood supply in reconstructing a 10-mm-long gap in the median nerve (MN) under conditions of local ischemia. A 10-mm-long median nerve defect was created in the right arm. A loose silicone tube was placed around the nerve...

Infra-red thermography evaluation of the region of the forepays innervated by the median nerve 90 days postoperatively. NG, nerve graft; CNF, conventional nerve flap; ANVF, arterialized neurovenous flap; PNF, prefabricated nerve flap. D, day after the beginning of the experiment. Numeric variables are expressed as average ± standard deviation. (DOC...

Walking track analysis results throughout the experiment. NG, nerve graft; CNF, conventional nerve flap; ANVF, arterialized neurovenous flap; PNF, prefabricated nerve flap. D, day after the beginning of the experiment. Numeric variables are expressed as average ± standard deviation. (DOCX)

Evaluation of retrograde marking of the right median nerve proximally to the lesion site, of the right C7 dorsal ganglion and of the right ventral horn of the spinal cord at the C7 level. NG, nerve graft; CNF, conventional nerve flap; ANVF, arterialized neurovenous flap; PNF, prefabricated nerve flap. N/A, non-applicable. All parameters are express...

Summary of the correlations found between functional motor variables and neurophysiological and histomorphometric variables. CMAP, compound muscle action potentials; FCR, flexor carpi radialis; AUC, area under the curve; MN, median nerve; DRG, dorsal root ganglion. (DOCX)

Summary of the correlations found between nociception assessment 90 days after surgery and functional motor, neurophysiological and histomorphometric variables. D90, ninety days after surgery; CMAP, compound muscle action potentials; MN, median nerve; DRG, dorsal root ganglion. (DOCX)

Histomorphometric evaluation of the right median nerve distally to the repair zone and of the vascular density in the middle portion of the reconstructed nerve defect in the different experimental groups. NG, nerve graft; CNF, conventional nerve flap; ANVF, arterialized neurovenous flap; PNF, prefabricated nerve flap. N/A, non-applicable. All param...

Background Many fundamental questions regarding the blood supply to the integument of the rat remain to be clarified, namely the degree of homology between rat and humans. The aim of this work was to characterize in detail the macro and microvascular blood supply to the integument covering the ventrolateral aspect of the abdominal wall of the rat....

Efficiency of optical-electronic systems: methods application for the analysis of structural changes in the process of eye grounds diagnosis; Proc.SPIE 10445, art.no.104450S; Process of eye tomogram obtaining by means of optical coherent tomography is studied. Stages of idiopathic macula holes formation in the process of eye grounds diagnostics...

Background Although numerous experimental models of arterialized venous flaps (AVFs) have been proposed, no single model has gained widespread acceptance. The main aim of this work was to evaluate the survival area of AVFs produced with different vascular constructs in the abdomen of the rat. Methods Fifty-three male rats were divided into 4 group...

Free tissue transfer has been increasingly used in clinical practice since the 1970s, allowing reconstruction of complex and otherwise untreatable defects resulting from tumor extirpation, trauma, infections, malformations or burns. Free flaps are particularly useful for reconstructing highly complex anatomical regions, like those of the head and n...

Arterial distensibility (AD) measures the ability of relaxation for arteries in response to pressure changes. Its reduction is closely associated with an increased risk of cardiovascular disease and higher pulse wave velocity (PWV), the gold standard method for AD evaluation. Several factors can decrease AD and therefore increase arterial stiffness...

Eнерго-Збиральних (EЗ) методів, які полягають в отриманні енергії з навколишнього середовища або відновлення і зберігання енергії, що виробляється людським організмом в повсякденній діяльності. Проте, це вимагає спеціальних технологій і матеріалів та, як правило, мультидисциплінарної команди. З цієї причини, включення теми про енерго-збиральні мето...

Laser photoplethysmography in integrated evaluation of collateral circulation of lower extremities, Proc.SPIE 9816; The paper evaluated the diagnostic value of laser photoplethysmography when examining patients with chronic lower limb ischemia. A statistical analysis of the research results was made, and diagrams of relationship between the degre...

Laser photoplethysmography in integrated evaluation of collateral circulation of lower extremities, Proc.SPIE 9816; The paper evaluated the diagnostic value of laser photoplethysmography when examining patients with chronic lower limb ischemia. A statistical analysis of the research results was made, and diagrams of relationship between the degre...

The two-temperature model for a medium with free electrons subject to nonequilibrium heat transfer is considered. The possibility is shown for tailing of heating area boundaries and the existence of undamped heat waves due to the small duration of temperature pulses acting on the material. A quantitative estimate is made for parameters of the tempe...

Introdução: A Pseudomonas aeruginosa (PA) representa um problema significativo de saúde pública, causando morbilidade e mortalidade significativas, sendo premente obter novas visões de como se processa a infecção por esta bactéria in vivo. Metódos: Em 40 ratos Wistar induziu-se uma infecção associada a um corpo estranho, pela elevação de um retalho...

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– A pré-eclampsia (PE) afecta cerca de 2% das gravidezes e é uma das principais causas de mortalidade e morbilidade perinatal e materna. Recentemente vários estudos com o uso da ecocardiografia bidimensional têm demonstrado que a PE é caracterizada por uma redução marcada no débito cardíaco materno e aumento da resistência periférica, enquanto que...

The physical mechanism of undamped temperature waves and the conditions of generation thereof in media with a finite time of local thermal relaxation are examined. The wave frequency depends on the relaxation time and the parameters of the pulse action on a medium, and the lowest frequencies corre� spond, in particular, to air. These effects can be...

A new model for heat transfer in this paper is proposed. It combines idea of medium with memory and phase-lag model. Equation for a temperature field based on new heat transfer model was obtained and investigated with wave-like solutions. New model was compared with common models for non-stationary heat transfer by its wave-like solutions amplitude...

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The polarization state of light is a very significant source of information in biomedical imaging. A light polarization can be modified during its interaction with different biological tissues, according to its nature, disorders states and pathological conditions. So these changes of polarization can provide valuable diagnostic tools. In this artic...

In this paper we report a new method for determination of macular area of the retina obtained by optical coherent tomography (OCT). A novel program of image processing was developed for this purpose. The improved efficiency of proposed tools and it accuracy in the determination of the parameters in the macular area was checked by comparison of resu...

The recent advances in technology and detection methods, as well as its economic viability have pointed the analysis of exhaled breath as a promising tool for medical diagnosis or therapy monitoring. Since the concentration of the most Volatile Organic Compounds (VOCs) present in the exhaled breath is very low (ppbv - pptv range) it is important to...

In this article the wave solutions of heat transfer equations, for classical model and for two alternative non-stationary models (hyperbolic and model with a time delay) have been studied. Modeling of temperature impulse propagation was performed according to dispersion relations obtained from heat transfer equations. It was shown that propagation...

Analysis of lacrimal fluid is under attention of scientists and physicians as an open "window" for non-invasive assessment to relevant information about the health status. In the present work we propose an innovative method for the analysis of volatile metabolites present in the lacrimal fluid by non-invasive, fast and inexpensive technique: Ion Mo...

Presently, a high cost of some medical equipment is due not only the sophisticated technology, but also because the cost of his maintenance. The electronic devices implanted in the human body are examples for this constant maintenance, requiring sophisticated medical operations. Extra weight and volume addition to the electronic devices are also a...

The human body naturally uses heat to fight diseases. This fact was used to develop methods of treatment that are based on an artificially increased temperatures. Temperature may be increased locally then treatment is called local hyperthermia. In the other case it is called whole body hyperthermia if temperature of a whole body was increased. Most...

As adipocitoquinas desempenham funções importantes no metabolismo lipídico. O presente estudo tem como principal objectivo analisar eventuais correlações de algumas adipocitoquinas, parâmetros lipídicos e sub-fracções das LDL e HDL, no contexto da obesidade. O estudo foi efectuado em 54 indivíduos. Foram estudadas a adiponectina total (adipoT), a a...

RESUMO: A avaliação do sistema arterial para o diagnóstico e tratamento das doenças cardiovasculares tem desempenhado um importante papel na última década, sendo objecto de investigação clínica e tecnológica. De entre diversos parâmetros investigados, a medição da Velocidade da Onda de Pulso (VOP) enquanto meio complementar de diagnóstico é conside...