Helinando P de Oliveira

Helinando P de Oliveira
Universidade Federal do Vale do São Francisco (UNIVASF) · Colegiado de Engenharia Elétrica

PhD
Full professor of physics at Univasf (Brazil). Researcher in physics of new materials for energy storage.

About

168
Publications
23,163
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Introduction
Helinando Pequeno de Oliveira is full professor at the Electrical Engineering Department and Materials Science Institute, Universidade Federal do Vale do São Francisco (UNIVASF) -Brazil. His work is focused on Condensed Matter Physics, with particular interest in the development of nanocomposites for supercpacitors, photocatalysts and electrochemical sensors.
Additional affiliations
May 2012 - November 2012
Massachusetts Institute of Technology
Position
  • Visiting professor
September 2004 - December 2020
Universidade Federal do Vale do São Francisco (UNIVASF)
Position
  • Professor (Full)

Publications

Publications (168)
Article
We study black hole formation during the gravitational collapse of a massless scalar field in asymptotically D-dimensional anti-de Sitter AdS_{D} spacetimes for D=4, 5. We conclude that spherically symmetric gravitational collapse in asymptotically AdS spaces is turbulent and characterized by a Kolmogorov-Zakharov spectrum. Namely, we find that aft...
Article
Full-text available
The use of conventional plastics for food packaging introduces serious environmental risks (soil and water). An alternative to minimize these risks is based on the use of biopolymers, which introduce ecological benefits for the deterioration process as well as extending the shelf life of food. Biopolymers are a diverse group of materials, with diff...
Article
Full-text available
A biomass-amino silica functionalized material was successfully prepared by a simple sol-gel similar method. APTES was added to a rich tannin grape residue to improve its physicochemical properties and enhance adsorption performance. The APTES functionalization led to significant changes in the material’s characteristics. The functionalized materia...
Article
The development of self-powered systems applied in wearable electronics based on triboelectric nanogenerators introduces advances in the Internet of Things, wireless communication, and biomedical fields. For this, efforts have been conducted to substitute metal-based electronics with non-conventional components such as conducting polymer, carbon de...
Article
The production of antibacterial polymer-based nanocomposites applied as coatings for tissue engineering scaffolds (such as fish skin) can be considered as an important strategy to be applied in the control of bacterial contaminations. Herein, it is proposed the incorporation of conducting polymers (polypyrrole and polyaniline) decorated with silver...
Article
The internet of things opened new possibilities relative to the integration of wearable electronics in textile-based devices, allowing the development of new technologies in energy storage and energy harvesting area, sensors, actuators and the following step of integration with the internet for the transmission of data. In particular, flexible phot...
Article
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Preparing sustainable and highly efficient biochars as electrodes remains a challenge for building green energy storage devices. In this study, efficient carbon electrodes for supercapacitors were prepared via a facile and sustainable single-step pyrolysis method using spruce bark as a biomass precursor. Herein, biochars activated by KOH and ZnCl2...
Article
Preparing sustainable and highly efficient biochars as electrodes remains a challenge for building green energy storage devices. In this study, efficient carbon electrodes for supercapacitors were prepared via a facile and sustainable single-step pyrolysis method using spruce bark as biomass precursor. Herein, biochars activated by KOH and ZnCl2 ar...
Article
Full-text available
In this work, Norway spruce bark was used as a precursor to prepare activated biochars (BCs) via chemical activation with potassium hydroxide (KOH) as a chemical activator. A Box-Behnken design (BBD) was conducted to evaluate and identify the optimal conditions to reach high specific surface area (SSA) and high mass yield BC samples. The studied BC...
Article
The development of eco-friendly prototypes for wound dressing systems represents an important source of investigation about alternatives for the treatment of severe infections. The production of antibacterial agents free of antibiotics, based on natural products and biological supports is a hot topic for science applied in circular economy concepts...
Article
The oncogenic human papillomavirus (HPV) is an excellent biomarker for cervical cancer screening. The present research reports the construction of an integrated sensor platform (biosensorMY11 and biosensorp53) for the impedimetric detection of the HPV L1 sequence and p53 tumor suppressor gene. The nanostructured biosensor is composed of electrosynt...
Article
Wound dressings based on natural materials, such as fish skin, represent an important strategy for the treatment of burns. Despite their utility, contamination of these natural materials with bacteria (planktonic and biofilm forms) introduces significant risks to patients under treatment. This disadvantage can be overcome by modifying the material’...
Presentation
Full-text available
This Special Issue is devoted to the application of the electrical impedance spectroscopy technique for the characterization of a wide range of materials. The characterization of such electrochemical devices as well as high and intermediate temperature gas sensors, biosensors, fuel cells, resistive, capacitive, and impedance sensors via impedance s...
Patent
A presente invenção estende-se ao processo de obtenção de eletrodos compósitos flexíveis a partir de membranas proteicas, nanoestruturas de carbono (NEC) e polímeros intrinsicamente condutores (PIC), mas não somente esses, através da técnica de ultrasonicação e a seu uso como eletrodos na preparação de dispositivos supercapacitores orgânicos flexív...
Article
The quest to develop flexible membrane-like supercapacitors to be applied in advanced electronic devices with a flexible structure is important for the modern world. In this study, we developed biomass-based supercapacitors by depositing activated carbon on an eggshell membrane and subsequently coating these with polypyrrole in a two-step procedure...
Article
Full-text available
Biobased carbon materials (BBC) obtained from Norway spruce (Picea abies Karst.) bark was produced by single-step chemical activation with ZnCl2 or KOH, and pyrolysis at 800 °C for one hour. The chemical activation reagent had a significant impact on the properties of the BBCs. KOH-biobased carbon material (KOH-BBC) had a higher specific surface ar...
Article
Full-text available
Biobased carbon materials (BBC) obtained from Norway spruce (Picea abies Karst.) bark was produced by single-step chemical activation with ZnCl2 or KOH, and pyroly-sis at 800°C for one hour. The chemical activation reagent had a significant impact on the properties of the BBCs. KOH-biobased carbon material (KOH-BBC) had a higher specific surface ar...
Article
RESUMO A atividade antibacteriana de nanopartículas metálicas (e em especial de prata) vem sendo explorada ao longo do tempo em diferentes formulações químicas para agentes biológicos livres de antibióticos. A produção dessas partículas por rotas ambientalmente responsáveis representa uma estratégia extremamente relevante por apresentar baixo custo...
Article
The development of supramolecular structures (conducting hydrogels) obtained from the charge–charge interaction of sodium dodecyl sulfate micelles and oppositely charged polypyrrole chains represents an important step to obtain self-supported and flexible electrodes for supercapacitors. Herein, the energy density of polypyrrole hydrogel-based super...
Article
1,8-cineole is a monoterpene commonly used by the food, cosmetic, and pharmaceutical industries owing to its flavor and fragrances properties. In addition, this bioactive monoterpene has demonstrated bactericidal and fungicidal activities. However, such activities are limited due to its low aqueous solubility and stability. This study aimed to deve...
Article
The use of unmodified and chemically treated natural fibers for water remediation (removal of chemical residues/oil spills and organic wastewater from water) is a significant and low‐cost strategy to reduce the contamination of aquifers with metal ions, as well as marine environments with oil spills and water bodies with organic dyes. Furthermore,...
Article
O dissulfeto de molibdênio é um material amplamente utilizado para remediação ambiental tendo em vista sua excelente capacidade de adsorção, que é atribuída principalmente aos sítios ativos de enxofre na superfície do MoS2. Além disso, este material possui vantagens quando comparado com outros fotocatalisadores, como por exemplo por alta atividade...
Article
Full-text available
Wearable self-powered sensors represent a theme of interest in the literature due to the progress in the Internet of Things and implantable devices. The integration of different materials to harvest energy from body movement or the environment to power up sensors or act as an active component of the detection of analytes is a frontier to be explore...
Article
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Caseous lymphadenitis (CLA) is a chronic disease that affects small ruminants and causes economic losses in the associated breeding system. The causative agent of CLA is Corynebacterium pseudotuberculosis, a Gram-positive bacterium that exhibits tropism for external and internal lymph nodes and induces abscess formation in the host. Bacterial commu...
Article
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Abstract The development of polypyrrole-based nanocomposites as alternative antibacterial agents represents a promising strategy to be applied against the prevailing multi-resistant bacteria. Herein, it is reported the most recent development of antibacterial materials based on the combination of polypyrrole and different fillers (metal nanoparticl...
Article
Full-text available
Cheap and efficient carbon electrodes (CEs) for energy storage systems (ESS) such as supercapacitors (SCs) and batteries are an increasing priority issue, among other things, due to a globally increasing share of intermittent electricity production (solar and wind) and electrification of transport. The increasing consumption of portable and non-por...
Article
Full-text available
In this study, samples of pristine and chemically modified coconut shells are used as adsorbents for the removal of crystal violet from an aqueous solution. The modification based on NaOH treatment of coconut shell fibers was evaluated by scanning electron microscopy and Fourier transform infrared spectroscopy. The dye uptake efficiency was evaluat...
Article
Full-text available
Some species of Lactobacillus have demonstrated beneficial health effects being applied in the production of food supplements. Thus, the incorporation of viable cells as encapsulated probiotics represents an essential condition to be considered in new strategies for the controlled release of microorganisms. Herein, the massive encapsulation of Lact...
Article
The required treatment and monitoring of contaminants in wastewater reinforces the development of low-cost adsorbents/chemosensors, introducing advantages relative to the detection/removal of toxic metals and dyes. Herein, it is reported a two-step process of fabrication of fluorescent carbon dots via the hydrothermal treatment of amino acids for t...
Article
Full-text available
The energy autonomy of self-powered wearable electronics depends on the adequate development of new technologies for energy harvesting and energy storage devices based on textile fibers to facilitate the integration with truly flexible and wearable devices. Silk fiber-based systems are attractive for the design of biomedical devices, lithium-ion ba...
Article
Full-text available
The growth of Agroecology courses at different levels is a reality in Brazil. This work presents a systematic mapping of the literature on the occurrence of Education in Agroecology at different levels of education in the country. For that it investigates the methodologies, the challenges, the contribuitions and where it has ocurred. 228 papers wer...
Article
Our objectives were to identify genes of the multi-drug efflux system and to evaluate the antimicrobial activities of polypyrrole nanoparticles (PPy-NPs) and aqueous extract of Moringa oleifera against Staphylococcus spp. isolated from dairy farms in Northeast Brazil. Initially, 162 Staphylococcus spp. isolates were subjected to in vitro antimicrob...
Article
Full-text available
Carbon dots and carbon dots-based nanocomposites have found a myriad of technological applications. Despite the primary use of carbon dots as catalysts in the reduction process to form metal nanoparticles, their strong interaction with metal nanostructures in nanocomposites can be further exploited. By tuning the emission of carbon dots and the abs...
Article
Full-text available
The development of environmentally friendly prototypes for use as antibacterial agents and as alternatives to antibiotics is a necessary step toward the control of infections. With this in mind, the production of hybrid composites based on natural and synthetic materials has been successfully explored. Herein, the chemical polymerization of polyani...
Article
Full-text available
Some recent developments in the preparation of biomass carbon electrodes (CEs) by using various biomass residues for application in energy storage devices such as batteries and supercapacitors are presented in this work. The application of biomass residues as the primary precursor for the production of CEs has been increasing over the last years du...
Article
Full-text available
Mastitis is one of the most important diseases in dairy milk systems. Molecular studies of the principal agents that are involved, as well as tests of bacterial sensitivity to plant extracts, are currently the most common forms of research related to this disease. The aim of the present study was to molecularly characterize isolates from cases of s...
Article
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With an estimated increasing oil demand in the coming decades, the need to explore non-applicable areas is intensified, and associated with them, before the high exploration costs, the need to improve available technologies. In this sense, in the last decade, the application of nanoparticles to improve drilling fluids has been intensified. In this...
Article
The health benefits and sensing applications of curcumin-based systems depend on their prevailing photophysical and chemical properties at a specific environment—the characteristic low solubility of curcumin in water hinders high-dosage based applications. To circumvent this drawback, curcumin has been incorporated in hydrophobic environments in na...
Article
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In the last decade, exploration in high temperature and pressure wells has motivated the improvement of drilling fluids with the application of nanoparticles. In this context, nanoclay, the most available of nanoparticles, has been applied in the development of nanofluids, mainly associated with polymers. In parallel, among the polymers used, xanth...
Article
A new coronavirus appears in China in December 2019, subsequently threatening the world, it was identified as Covid-19. Its main symptomatic characteristic is directly linked to acute respiratory failure, however there are asymptomatic cases of the disease, mainly in the group not considered at risk. For the treatment of the disease a variety ofant...
Chapter
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Lichens are the symbiotic organisms formed by one species of fungus associated to one or more species of green algae and/or cyanobacteria. The relationship between these organisms results in a metabolism that culminates in a production of exclusive compounds, named lichen substances, also known as lichen compounds or lichen acids. These products ar...
Article
Algae of the genus Prototheca are microorganisms involved in the occurrence of diseases in humans and animals. In bovine species, Prototheca spp. cause environmental mastitis, productive losses in dairy herds, mainly leading to the discard of infected cows. Currently, there are no effective anti-Prototheca spp. drugs to combat this infection. Thus,...
Article
Full-text available
The aim of the present study was to evaluate the antibacterial behavior of polypyrrole nanoparticles (PPy-NPs) in water against biofilm producer or not S. aureus isolated from cows and goats with mastitis. One hundred and thirty-eight isolates of S. aureus were initially evaluated for biofilm formation by spectrophotometry in microplates. In additio...
Article
Some species of Lactobacillus (Gram-positive bacilli) are promising probiotics with positive physiological effects on prevention and treatment of diseases. A critical drawback related to the action of these microorganisms refers to the sustainable viability of cells at adverse conditions (under storage, packing and at gastrointestinal tract flux) –...
Article
The improvement in the electrochemical performance of flexible electrodes for supercapacitors depends on adequate doping level of pseudocapacitive prototypes incorporated into truly flexible devices. The interaction of graphene nanoplatelets, carbon dots and polypyrrole on flexible supports of eggshell membranes offers an adequate combination in wh...
Article
Full-text available
Antimicrobial resistance in bacteria, such as Staphylococcus aureus, has been the subject of many assistance studies of alternatives for the treatment of infections. These studies aim to solve this problem for bacteria, such as biofilm formation. Aiming to control the emergence of the problem or enhance antibiotic activity, the data sources are ins...
Article
The feasibility of wearable electronics depends on the development of reliable energy storage devices that could combine high energy density to mechanical flexibility. A significant step towards this goal would be the preparation of supercapacitors prepared on truly flexible supports, which could present an adequate balance of Faradaic and non-Fara...
Article
The green synthesis of silver nanoparticles represents an important strategy for production of alternative antibacterial agents. Herein, the reduction of silver nanoparticles is provided by the action of leaf extract of Ziziphus joazeiro. The as-synthesized material presented pH-dependent behavior that affects the kinetics of nanoparticles nucleati...
Article
The production of more efficient yeast-based fuel cells (YFCs) depends on a combination of effective proton exchange membranes, electron mediators and current collectors. The adhesion of organisms on electrode surface plays a key role in the electron transfer process optimizing the generated power density. In this work, it is reported the preparati...
Article
Full-text available
We report an alternative random laser (RL) architecture based on a flexible and ZnO-enriched cellulose acetate (CA) fiber matrix prepared by electrospinning. The electrospun fibers, mechanically reinforced by polyethylene oxide and impregnated with zinc oxide powder, were applied as an adsorbent surface to incorporate plasmonic centers (silver nano...
Article
High-performance supercapacitors result from a conjunction of efforts in materials design and nanotechnology that elaborated solutions for electrodes and the expansion in voltage windows operation of storage devices. In terms of electrodes, the high surface area of graphene (2630 m2g-1) makes this carbon a widely used building block for supercapaci...
Article
This paper describes the adsorption of methylene blue and methyl orange from aqueous solution by eggshell membrane (pristine/modified with silver nanoparticles) which were analyzed by Fourier Transform Infrared/Raman spectroscopy and Scanning Electron Microscopy. The conditions for adsorption were varied in terms of pH, adsorbent mass, dye concentr...
Article
Full-text available
The development of highly conductive, flexible, mechanical reinforced and chemically modified cotton yarns for electrodes of supercapacitors represents an important advance in the energy storage devices applied in wearable electronics. The production of carbon-based conductive layers as supports for chemical polymerization of active polymeric mater...
Article
Plasmonically enhanced random lasing in eggshell biomembranes is reported using a hybrid metalorganic system comprised by Rhodamine 6G as gain medium and silver nanoparticles as the plasmonic metal. The scattering mechanism responsible for feedback in the random laser action arises from the submicron randomly arranged structure of the eggshell biom...
Article
The detection of traces of substances by surface‐sensitive techniques such as surface enhanced Raman spectroscopy (SERS) explores the interaction of adsorbed molecules on plasmonic surfaces to improve the limit of detection of analytes. This article is an overview about recent development in SERS substrates applied in the detection of organophospho...
Article
The adhesion of pathogenic bacteria in medical implants and surfaces is a health-related problem that requires strong inhibition against bacterial growth and attachment. In this work, we have explored the enhancement of antibacterial activity of metal free-based composites under external electric field. It affects the oxidation degree of polypyrrol...