ABSTRACT
The particle morphology of LiNiO2 (LNO), the final product of Co-free high-Ni layered oxide cathode materials, must be engineered to prevent the degradation of electrochemical performance caused by the H2-H3 phase transition. Introducing a small amount of dopant oxides (Nb2O5 as an example) during the electrolysis synthesis of the Ni(OH)2 precursor facilitates the engineering of the primary particles of LNO, which is quick, simple, and inexpensive. In addition to the low concentration of Nb that entered the lattice structure, a combination of advanced characterizations indicates that the obtained LNO cathode material contains a high concentration of Nb in the primary particle boundaries in the form of lithium niobium oxide. This electrolysis method facilitated LNO (EMF-LNO) engineering successfully, reducing primary particle size and increasing particle packing density. Therefore, the EMF-LNO cathode material with engineered morphology exhibited increased mechanical strength and electrical contact, blocked electrolyte penetration during cycling, and reduced the H2-H3 phase transition effects.
ABSTRACT
Niobate Li+ -storage anode materials with shear ReO3 crystal structures have attracted intensive attention due to their inherent safety and large capacities. However, they generally suffer from limited rate performance, cyclic stability, and temperature adaptability, which are rooted in their insufficient interlayer spacings. Here, sodium niobate (NaNb13 O33 ) micron-sized particles are developed as a new anode material owning the largest interlayer spacing among the known shear ReO3 -type niobates. The large interlayer spacing of NaNb13 O33 enables very fast Li+ diffusivity, remarkably contributing to its superior rate performance with a 2500 to 125 mA g-1 capacity percentage of 63.2%. Moreover, its large interlayer spacing increases the volume-accommodation capability during lithiation, allowing small unit-cell-volume variations (maximum 6.02%), which leads to its outstanding cyclic stability with 87.9% capacity retention after as long as 5000 cycles at 2500 mA g-1 . Its cyclic stability is the best in the research field of niobate micron-sized particles, and comparable to that of "zero-strain" Li4 Ti5 O12 . At a low temperature of -10 °C, it also exhibits high rate performance with a 1250 to 125 mA g-1 capacity percentage of 65.6%, and even better cyclic stability with 105.4% capacity retention after 5000 cycles at 1250 mA g-1 . These comprehensively good electrochemical results pave the way for the practical application of NaNb13 O33 in high-performance Li+ storage.
ABSTRACT
Plants face recurrent drought events, and previous stresses can influence their responses to subsequent stress episodes. Studies on drought stress memory are recent in citriculture, although they show promise as a tool for crop improvement. Here, we investigated whether stress memory mechanisms can be detected in citrus plants grafted with buds from plants subjected to recurrent water deficit. Three rootstock varieties, namely 'Rangpur Santa Cruz' lime, 'Sunki Maravilha' mandarin and 'Sunki Tropical' mandarin, in combination with 'Valencia' orange, were either maintained under full irrigation or subjected to one, two, or three water deficit cycles. Buds from 'Valencia' orange were grafted onto 'Swingle' citrumelo rootstocks and were evaluated. This combination displayed improved physiological and biochemical performance under water limitation, especially 'Valencia' buds grafted onto 'Sunki Maravilha', with better photosynthetic performance under water deficit. These findings indicate that genotype-dependent epigenetic memory is a key factor in restoring citrus plants' capacity to rely on previous stress experiences to restore better photosynthetic and physiological responses when undergoing new water deficit events. Therefore, epigenetic marks can be stored and transmitted to new citrus plants and are a promising alternative to enable increased water deficit tolerance when plants are then challenged by drought-prone environments.
Subject(s)
Citrus sinensis , Citrus , Citrus/genetics , Droughts , Photosynthesis , WaterABSTRACT
Salinity is still one of the main factors that limit the growth and production of crops. However, currently, hydrogen peroxide (H2O2) priming has become a promising technique to alleviate the deleterious effects caused by salt. Therefore, this study aimed to test different leaf spraying strategies with H2O2 for acclimation of sunflower plants to salt stress, identifying the main physiological and biochemical changes involved in this process. The experiment was conducted in a completely randomized design, with four replications. Initially, four concentrations of H2O2 were tested (0.1; 1; 10 and 100 mM) associated with different applications: 1AP - one application (48 h before exposure to NaCl); 2AP - two applications (1AP + one application 7 days after exposure to NaCl) and 3AP - three applications (2AP + one application 14 days after exposure to NaCl), besides this two reference treatments were also added: control (absence of NaCl and absence of H2O2) and salt control (presence of 100 mM of NaCl and absence of H2O2). The experiment was conducted in hydroponic system containing Furlani's nutrient solution. Salt stress reduced the growth of sunflower plants, however, the H2O2 priming through leaf spraying was able to reduce the deleterious effects caused by salt, especially in the 1 mM H2O2 treatment with one application. H2O2 acts as a metabolic signal assisting in the maintenance of ionic and redox homeostasis, and consequently increasing the tolerance of plants to salt stress.
ABSTRACT
The Brazilian sandy coastal plain named restinga is frequently subjected to particulate and gaseous emissions from iron ore factories. These gases may come into contact with atmospheric moisture and produce acid rain. The effects of the acid rain on vegetation, combined with iron excess in the soil, can lead to the disappearance of sensitive species and decrease restinga biodiversity. The effects of iron ore dust deposition and simulated acid rain on photosynthesis and on antioxidant enzymes were investigated in Eugenia uniflora, a representative shrub species of the restinga. This study aimed to determine the possible utility of this species in environmental risk assessment. After the application of iron ore dust as iron solid particulate matter (SPM(Fe)) and simulated acid rain (pH 3.1), the 18-month old plants displayed brown spots and necrosis, typical symptoms of iron toxicity and injuries caused by acid rain, respectively. The acidity of the rain intensified leaf iron accumulation, which reached phytotoxic levels, mainly in plants exposed to iron ore dust. These plants showed the lowest values for net photosynthesis, stomatal conductance, transpiration, chlorophyll a content and electron transport rate through photosystem II (PSII). Catalase and superoxide dismutase activities were decreased by simulated acid rain. Peroxidase activity and membrane injury increased following exposure to acid rain and simultaneous SPM(Fe) application. Eugenia uniflora exhibited impaired photosynthetic and antioxidative metabolism in response to combined iron and acid rain stresses. This species could become a valuable tool in environmental risk assessment in restinga areas near iron ore pelletizing factories. Non-invasive evaluations of visual injuries, photosynthesis and chlorophyll a fluorescence, as well as invasive biochemical analysis could be used as markers.
Subject(s)
Acid Rain/toxicity , Iron/toxicity , Syzygium/metabolism , Catalase/analysis , Dust , Environmental Monitoring , Oxidative Stress/drug effects , Peroxidase/analysis , Photosynthesis/drug effects , Plant Leaves/drug effects , Risk Assessment , Superoxide Dismutase/analysis , Syzygium/drug effects , Syzygium/enzymologyABSTRACT
Um dos erros mais comuns em reabilitação oral é a montagem incorreta dos modelos de gesso no articulador. Por isso, devemos também dar uma atenção especial nessa importante etapa, da mesma maneira que em qualquer outra fase do tratamento do paciente. Este trabalho apresenta uma técnica para transferência direta do molde da arcada superior do paciente para o articulador, conhecida como técnica Zanetti. Esse procedimento é realizado com o auxílio do conjunto Zanetti, o qual consegue transferir os registros da arcada superior, seja ela totalmente dentada, parcialmente ou totalmente desdentada, do paciente para o articulador, numa só etapa, sem a necessidade de confeccionarem-se bases de prova ou de registro, planos de orientação, utilização do garfo do arco facial e dos meios macios de transferência
Subject(s)
Dental Articulators , Dental Impression Technique , Models, Dental , Dental EquipmentABSTRACT
This study introduces a new impression procedure that permits mounting the maxillary stone cast in an articulator for any patient treatment and is applicable to any dental arch with any impression material. A transfer tray was designed that makes it possible to transfer the patient's maxillary impression to the articulator in a one-stage procedure without the need for making record bases and occlusion rims or the need to use a face-bow bite fork
Subject(s)
Temporomandibular Joint/physiology , Dental Articulators/standards , Printing/standardsABSTRACT
Apresentaçäo de uma nova técnica de moldagem, obtençäo, transferência e montagem do modelo de gesso no articulador, em qualquer caso que exija a utilizaçäo de um articulador para o diagnóstico e planejamento do tratamento de pacientes. Os autores idealizaram uma moldeira de transferência, com a qual consegue-se transferir os registros da arcada superior do paciente para o articulador numa só etapa, sem a necessidade de confeccionarem-se bases de prova e planos de orientaçäo, utilizaçäo do garfo do arco facial e dos meios macios de transferência do modelo