Hydrothermal processing of biomass may be able to overcome a series of problems associated with the thermochemical conversion of lignocellulosic material into energy and fuels. Investigating the process parameters and an adequate process description is one of the first steps to being able to design and optimize a certain treatment concept. In the present article, we studied process evolution with respect to reaction time in order to evaluate structure changes and kinetics of corn stover decomposition in a hydrothermal reactor. The effect of the biomass-to-H₂O ratio was also investigated. A pilot-scale reactor of 18.75 L was used to conduct hydrothermal processing runs at 250 °C at different reaction times (60, 120 and 240 min) and biomass-to-H₂O ratios (1:10, 1:15 and 1:20). Solid phase products were characterized by thermogravimetry (TG), scanning electron microscopy (SEM), elemental composition (EDX), crystalline phases by X-ray diffraction (XRD) and surface area (BET). For the experiments with a constant reaction time, the yields of hydro-char, aqueous and gaseous phases varied between 31.08 and 35.82% (wt.), 54.59 and 60.83% (wt.) and 8.08 and 9.58% (wt.), respectively. The yields of hydro-char and gases tend to increase with higher biomass-to-H₂O ratios, while aqueous phase yields are lower when using lower ratios. As expected, the yields of liquid and gases are higher when using higher reaction times, but there is a reduction in hydro-char yields. TG showed that 60 min was not enough to completely degrade the corn stover, while 120 and 240 min presented similar results, indicating an optimized time of reaction between 120 and 240 min. SEM images, elemental composition and XRD of hydro-char showed that higher biomass-to-H₂O ratios increase the carbonization of corn stover. The surface area analysis of hydro-char obtained at 250 °C, 2.0 °C/min, a biomass-to-H₂O ratio of 1:10 and 240 min showed a surface area of 4.35 m²/g, a pore volume of 18.6 mm³/g and an average pore width of 17.08 μm. The kinetic of corn stover degradation or bio-char formation was correlated with a pseudo-first-order exponential model, exhibiting a root-mean-square error (r²) of 1.000, demonstrating that degradation kinetics of corn stover with hot-compressed H₂O, expressed as hydro-char formation, is well described by an exponential decay kinetics.

This work aims to systematically investigate the influence of process temperature, biomass-to-water ratio, and production scales (laboratory and pilot) on the chemical composition of aqueous and gaseous phases and mass production of chemicals by hydrothermal processing of Açaí (Euterpe oleraceae, Mart.) seeds. The hydrothermal carbonization was carried out at 175, 200, 225, and 250 °C at 2 °C/min and a biomass-to-water ratio of 1:10; at 250 °C at 2 °C/min and biomass-to-water ratios of 1:10, 1:15, and 1:20 in technical scale; and at 200, 225, and 250 °C at 2 °C/min and a biomass-to-water ratio of 1:10 in laboratory scale. The elemental composition (C, H, N, S) in the solid phase was determined to compute the HHV. The chemical composition of the aqueous phase was determined by GC and HPLC and the volumetric composition of the gaseous phase using an infrared gas analyzer. For the experiments in the pilot test scale with a constant biomass-to-water ratio of 1:10, the yields of solid, liquid, and gaseous phases varied between 53.39 and 37.01% (wt.), 46.61 and 59.19% (wt.), and 0.00 and 3.80% (wt.), respectively. The yield of solids shows a smooth exponential decay with temperature, while that of liquid and gaseous phases showed a smooth growth. By varying the biomass-to-water ratios, the yields of solid, liquid, and gaseous reaction products varied between 53.39 and 32.09% (wt.), 46.61 and 67.28% (wt.), and 0.00 and 0.634% (wt.), respectively. The yield of solids decreased exponentially with increasing water-to-biomass ratio, and that of the liquid phase increased in a sigmoid fashion. For a constant biomass-to-water ratio, the concentrations of furfural and HMF decreased drastically with increasing temperature, reaching a minimum at 250 °C, while that of phenols increased. In addition, the concentrations of CH₃COOH and total carboxylic acids increased, reaching a maximum concentration at 250 °C. For constant process temperature, the concentrations of aromatics varied smoothly with temperature. The concentrations of furfural, HMF, and catechol decreased with temperature, while that of phenols increased. The concentrations of CH₃COOH and total carboxylic acids decreased exponentially with temperature. Finally, for the experiments with varying water-to-biomass ratios, the productions of chemicals (furfural, HMF, phenols, cathecol, and acetic acid) in the aqueous phase is highly dependent on the biomass-to-water ratio. For the experiments at the laboratory scale with a constant biomass-to-water ratio of 1:10, the yields of solids ranged between 55.9 and 51.1% (wt.), showing not only a linear decay with temperature but also a lower degradation grade. The chemical composition of main organic compounds (furfural, HMF, phenols, catechol, and acetic acid) dissolved in the aqueous phase in laboratory-scale study showed the same behavior as those obtained in the pilot-scale study.

In this work, the effect of reaction time and biomass-to-H2O ratio on the structural evolution of hydro-char and kinetic of by hydrothermal processing of corn Stover with hot compressed H2O, have been systematically investigated. The experiments were carried out at 250 °C, heating rate of 2.0 °C/min, biomass-to-H2O ratio of 1:10, and reaction times of 60, 120, and 240 minutes, and at 250 °C, 240 minutes, heating rate of 2.0 °C/min, and biomass-to-H2O water ratio of 1:10, 1:15, and 1:20, using a pilot scale stirred tank reactor of 5 gallon. The characterization of solid phase products performed by thermo-gravimetric analysis, scanning electron microscope, energy dispersive X-ray spectroscopy, X-ray diffraction, and elemental analysis (C, N, H, S). The physical-chemistry properties of solid phase analyzed in terms of dry matter (DM), total organic content (TOC), and ash. The yields of solid and gas phases decrease linearly with decreasing biomass-to-H2O ratio, while that of liquid phases increases linearly. For constant biomass-to-H2O ratio, the yields of solid, liquid, and gaseous reaction products varied between 52.97 and 35.82% (wt.), 44.84 and 54.59% (wt.), and 2.19 and 9.58% (wt.), respectively. The yield of solids decreases exponentially by decreasing the reaction time, while the yields of liquid and gas phases increase exponentially. For constant biomass-to-H2O ratio, TG/DTG curves shows that reaction time of 60 minutes was not enough to carbonize corn Stover. For constant reaction time, TG/DTG curves shows that increasing the H2O-to-biomass ratio worse the carbonization of corn Stover. For constant biomass-to-H2O ratio, the SEM images show the main morphological structure of the corn Stover remains practically unchanged, while for constant reaction time, SEM images show that plant microstructure retains part of its original morphology, demonstrating that a decrease on biomass-to-H2O ratio worse the carbonization of corn Stover. For constant biomass-to-H2O ratio, the EDX analysis shows that the carbon content in hydro-char increases with reaction time, while for constant reaction time, the carbon content decreases with increasing biomass-to-H2O ratio. The kinetic of corn Stover degradation was correlated with a pseudo-first order exponential model, exhibiting a root-mean-square error (r2) of 1.000, demonstrating that degradation kinetics of corn Stover with hot compressed H2O, expressed as hydro-char formation, is well described by an exponential decay kinetics.

A displasia ectodérmica (DE) é uma condição genética rara que afeta o desenvolvimento de estruturas originadas do ectoderma, incluindo pele, cabelo, unhas e dentes. Em pacientes com DE, é comum encontrar dentes em formato conóide, hipodontia ou anodontia, além de alterações na salivação e dificuldades sociais devido à aparência facial e dentária. O diagnóstico precoce é essencial para minimizar impactos funcionais e emocionais. Assim, o relato de caso desse artigo descreve a reabilitação de uma criança com DE realizada na clínica-escola da Universidade Federal do Pará (UFPA). O paciente, J.M.S., um menino de quatro anos, apresentava timidez e queixas de "bullying" na escola por conta de seus dentes pontiagudos. No exame clínico, foram identificados cabelos finos, pele seca, nariz em sela e microdontia dos dentes decíduos, além da ausência congênita de um incisivo lateral. O diagnóstico foi confirmado pelo Serviço de Genética da UFPA, que identificou a forma hipohidrótica da DE. A reabilitação proposta envolveu técnicas de resina composta para devolver a funcionalidade e a estética dos dentes. O tratamento iniciou-se com adequação do meio bucal, controle do biofilme e escolha da cor da resina. A técnica com coroas de acetato foi aplicada em dentes superiores, enquanto a técnica de modelagem direta (mão livre) foi usada nos dentes inferiores. A resina composta foi polimerizada e ajustada para garantir a integridade oclusal e estética. Após o procedimento, o paciente relatou melhora significativa na autoestima e no convívio social, além de maior conforto ao mastigar alimentos. Como conclusão, esse caso reforça a importância da reabilitação precoce em crianças com DE para restaurar as funções fonética e mastigatória e promover bem-estar emocional. A abordagem multidisciplinar, envolvendo dentistas, ortodontistas e outros profissionais, é fundamental para garantir o acompanhamento contínuo e uma melhor qualidade de vida. O uso de técnicas conservadoras, como resinas compostas, demonstrou ser eficaz na recuperação estética e funcional de dentes decíduos afetados pela displasia ectodérmica.

Photobiomodulation (PBM) has emerged as a promising therapeutic technology in contemporary dentistry, providing benefits such as analgesia, inflammatory modulation, and accelerated tissue healing, without relevant side effects. This narrative review explores the biological foundations of PBM and its clinical applications in different dental specialties, such as implantology, periodontics, endodontics, orthodontics, pediatric dentistry, stomatology, and the treatment of temporomandibular disorders. The interaction of light with oral tissues promotes cellular effects mediated by mitochondria, optimizing the biological response and favoring tissue repair. The technical parameters, advantages, limitations, and future perspectives are discussed, including the need for standardization of clinical protocols and strengthening of professional training. In addition, the article highlights the importance of evidence-based practice, individualized approach, and integration of photobiomodulation into dental care, especially in patients with specific needs, such as those with systemic conditions. The expansion of the use of PBM depends on scientific advances, continuing education and public policies that value innovative and safe technologies for oral health care.

Pacientes com necessidades especiais, especialmente aqueles com comprometimentos sistêmicos, representam um desafio crescente na prática odontológica clínica. Esta revisão narrativa explora as principais doenças sistêmicas que exigem adaptações específicas no atendimento odontológico, incluindo diabetes mellitus, hipertensão, distúrbios cardiovasculares, câncer, doenças renais e hepáticas crônicas, distúrbios hematológicos e imunossupressão. Essas condições influenciam diretamente o planejamento diagnóstico e terapêutico, aumentando o risco de complicações como sangramentos, infecções, atraso na cicatrização e descompensações sistêmicas. A revisão destaca a importância do cuidado individualizado, da colaboração interprofissional e da tomada de decisão clínica baseada em parâmetros laboratoriais e na estabilidade da doença. Barreiras de acesso, como a escassez de serviços especializados e a formação acadêmica limitada, também são discutidas. Aspectos éticos e legais, como bioética, autonomia do paciente e responsabilidade profissional, são abordados como pilares fundamentais do cuidado. Apesar da existência de diretrizes clínicas, ainda há lacunas na preparação profissional e na infraestrutura dos serviços. Este artigo defende a inclusão de conteúdos sobre deficiência nos currículos de Odontologia, a ampliação de centros especializados e políticas públicas que assegurem o acesso equitativo aos serviços de saúde bucal. A Odontologia deve avançar rumo a uma prática mais inclusiva, ética e baseada em evidências.