Intermediate Regeneration Research Articles

Reusable and inductively regenerable magnetic activated carbon for removal of organic micropollutants from secondary wastewater effluents

This work introduces a new sustainable alternative of powdered activated carbon (PAC) - magnetically harvestable and reusable after regeneration via inductive heating - for the adsorptive removal of organic micropollutants (OMP) from secondary wastewater effluents. For this purpose, two commercial PACs - lignite “L” (1187 m2/g) and coconut “C”-based (1524 m2/g) - were modified with magnetic iron oxide following two different synthesis approaches: infiltration (“infiltr”) and surface deposition (“depos”) route. The resulting magnetic powdered activated carbons (mPAC) and their precursor PACs were fully characterized before application. The iron oxide content of the modified “L” and “C” samples was ∼30 % and ∼20 %, respectively. Iron oxide gives the PAC beneficial magnetic properties for easy magnetic separation and simultaneously acts as an inductively heatable agent for the carbon regeneration. The infiltrated samples displayed better inductive heating performance and regeneration than their deposited counterparts. Tests with real wastewater showed fast adsorption kinetics of the organic load following the pseudo-second-order kinetic model. Adsorption isotherms were compliant with the Freundlich isotherm model. Sample “L-infiltr” had the best overall adsorption performance throughout 5 reuse cycles when intermediately inductively regenerated (<3 % drop in organics removal per cycle with intermediate regeneration vs. ∼10 % drop per cycle without regeneration). The treated supernatant was additionally tested for 31 representative organic micropollutants and their transformation products (pharmaceuticals, personal care products, industrial chemicals, etc.), where 26 OMPs had consistently high removal (>85 %) throughout 5 cycles with intermediate regeneration and for 28 OMPs the total adsorption efficiency dropped by <5 % after 5 cycles.

Investigating the developmental onset of regenerative potential in the annelid Capitella teleta

AbstractAn animal's ability to regrow lost tissues or structures can vary greatly during its life cycle. The annelid Capitella teleta exhibits posterior, but not anterior, regeneration as juveniles and adults. In contrast, embryos display only limited replacement of specific tissues. To investigate when during development individuals of C. teleta become capable of regeneration, we assessed the extent to which larvae can regenerate. We hypothesized that larvae exhibit intermediate regeneration potential and demonstrate some features of juvenile regeneration, but do not successfully replace all lost structures. Both anterior and posterior regeneration potential of larvae were evaluated following amputation. We used several methods to analyze wound sites: EdU incorporation to assess cell proliferation; in situ hybridization to assess stem cell and differentiation marker expression; immunohistochemistry and phalloidin staining to determine presence of neurites and muscle fibers, respectively; and observation to assess re‐epithelialization and determine regrowth of structures. Wound healing occurred within 6 h of amputation for both anterior and posterior amputations. Cell proliferation at both wound sites was observed for up to 7 days following amputation. In addition, the stem cell marker vasa was expressed at anterior and posterior wound sites. However, growth of new tissue was observed only in posterior amputations. Neurites from the ventral nerve cord were also observed at posterior wound sites. De novo ash expression in the ectoderm of anterior wound sites indicated neuronal cell specification, although the absence of elav expression indicated an inability to progress to neuronal differentiation. In rare instances, cilia and eyes re‐formed. Both amputations induced expanded expression of the myogenesis gene MyoD in preexisting tissues. Our results indicate that amputated larvae complete early, but not late, stages of regeneration, which indicates a gradual acquisition of regenerative ability in C. teleta. Furthermore, amputated larvae can metamorphose into burrowing juveniles, including those missing brain and anterior sensory structures. To our knowledge, this is the first study to assess regenerative potential of annelid larvae.

Catalytic Synthesis of Methyl Glycolate from Glyoxal Methanol Solution over Base Catalysts

The process of obtaining methyl glycolate from a methanolic solution of glyoxal over solid basic catalysts based on mixed oxides of magnesium, zirconium, and aluminum has been studied. According to obtained results, the selectivity of the methyl glycolate formation increases with increasing the basicity of the catalyst. The most selective coprecipitated MgO-ZrO2 provides almost 100 % methyl glycolate yield. The supported MgO-ZrO2/Al2O3 gives to 95 % yield of methyl glycolate with the formation of the glyoxal dimethyl acetal as a by-product. This catalyst could be reused several consecutive cycles without the need for intermediate regeneration. Methyl glycolate in a high 93 % yield can be obtained at 453 K over this solid catalyst in flow mode, which may be of practical interest.

Chem-bio interface design for rapid conversion of CO2 to bioplastics in an integrated system

Chem-bio interface design for rapid conversion of CO2 to bioplastics in an integrated system

Sulfated complex metal oxides solid acids with dual Brønsted-Lewis acidic property for production of 5-ethoxymethylfurfural from biomass-derived carbohydrates

The transformation of aldose-based carbohydrates into 5-ethoxymethylfurfural (EMF) is very challenging as compared to ketose-based carbohydrates, but the formers are more abundant and cheaper. Here, a series of sulfated complex metal oxides were synthesized for the conversion of aldose-based mono-, di-, and poly-saccharides, as well as starchy food waste into EMF. The catalysts were carefully characterized and the results showed that the type and strength of the acid sites were more important than their concentration. It was also shown that the efficiency of these catalysts was significantly affected by the metal species in the catalyst composition and followed the order tetra- > tri- > bi- > mono-component metal oxides based catalyst. Among the prepared catalysts, Zr-Sn-Fe-Al-O-S exhibited superior catalytic activity, with an EMF yield of 33.1% from glucose, and yields ranging from 4.1−26.3% for di-, poly-saccharides and starchy food waste in ethanol/dimethyl sulfoxide solvent system under glucose/catalyst mass ratio of 4. The role of co-solvent in the reaction pathway was also studied. It was found that the predominant reaction pathway for EMF production was closely related to the co-solvent amount. A kinetic model of glucose conversion to EMF was developed and the thermodynamic analysis was performed, the main features of the experimental observations can be described by the model. Zr-Sn-Fe-Al-O-S was reused for four runs without intermediate regeneration steps, showing a slight decay in activity. After reactivation by calcination before the fifth cycle, the catalyst recovered its activity, indicating good reusability and thermal stability.

ITRAQ-based proteomic profiling reveals protein alterations after traumatic brain injury and supports thyroxine as a potential treatment

Traumatic brain injury (TBI) is a primary cause of disability and death across the world. Previously, RNA analysis was widely used to study the pathophysiological mechanisms underlying TBI; however, the relatively low correlation between the transcriptome and proteome revealed that RNA transcription abundance does not reliably predict protein abundance, which led to the emergence of proteomic research. In this study, an iTRAQ proteomics approach was applied to detect protein alterations after TBI on a large scale. A total of 3937 proteins were identified, and 146 proteins were significantly changed after TBI. Moreover, 23 upregulated proteins were verified by parallel reaction monitoring (PRM), and fold changes in 16 proteins were consistent with iTRAQ outcomes. Transthyretin (Ttr) upregulation has been demonstrated at the transcriptional level, and this study further confirmed this at the protein level. After treatment with thyroxine (T4), which is transported by Ttr, the effects of T4 on neuronal histopathology and behavioral performance were determined in vivo (TBI + T4 group). Brain edema was alleviated, and the integrity of the blood brain barrier (BBB) improved. Escape latency in the Morris water maze (MWM) declined significantly compared with the group without T4 treatment. Modified neurological severity scores (mNSS) of the TBI + T4 group decreased from day 1 to day 7 post-TBI compared with the TBI + saline group. These results indicate that T4 treatment has potential to alleviate pathologic and behavioral abnormalities post-TBI. Protein alterations after T4 treatment were also detected by iTRAQ proteomics. Upregulation of proteins like Lgals3, Gfap and Apoe after TBI were reversed by T4 treatment. GO enrichment showed T4 mainly affected intermediate filament organization, cholesterol transportation and axonal regeneration. In summary, iTRAQ proteomics provides information about the impact of TBI on protein alterations and yields insight into underlying mechanisms and pathways involved in TBI and T4 treatment. Finally, Ttr and other proteins identified by iTRAQ may become potential novel treatment targets post-TBI.

Sulfonic acid-functionalized PCP(Cr) catalysts with Cr3+ and -SO3H sites for 5-ethoxymethylfurfural production from glucose.

5-Ethoxymethylfurfural (EMF) has been identified as a potential biofuel and fuel additive, for which the production from glucose (the most abundant and inexpensive monosaccharide) in a one-step process would be highly desirable. Here, the synthesis of sulfonic acid-functionalized porous coordination polymers (PCPs) and their application as catalysts for EMF synthesis are reported. PCP(Cr)-BA (PCP material with Cr3+ ions and H2BDC-SO3H linkers) and PCP(Cr)-NA (PCP material with Cr3+ ions and H2NDC(SO3H)2 linkers) materials containing both Cr3+ sites and Brønsted-acidic –SO3H sites were prepared. The morphology, pore structure, acidity, chemical composition, and thermal stability of the two functionalized PCP(Cr) catalysts were analyzed by systematic characterization. The catalysts featured a porous morphology and dual Cr3+ and –SO3H sites, which enabled the cascade conversion of glucose to EMF. PCP(Cr)-BA exhibited higher performance than PCP(Cr)-NA with an EMF yield of 23.1% in the conversion of glucose at 140 °C after 22 h in an ethanol/water system. In addition, the as-prepared catalyst exhibited a high stability in the current catalytic system for EMF production from glucose with a constant catalytic activity in a four-run recycling test without an intermediate regeneration step.

Hydrogen production by ethanol steam reforming: A study of Co- and Ce-based catalysts over FeCrAlloy monoliths

Co- and Ce-based structured catalysts deposited on FeCrAlloy monoliths have been prepared. A new two-step strategy for coating the monolith is used: (i) first, a MgAl2O4 spinel layer is generated on the FeCrAlloy substrate, and (ii) then, Co and Ce are incorporated in two different molar ratios by the conventional wet impregnation method. The spinel layer is formed from a solution of colloidal alumina and Mg(NO3)2, with an apparent viscosity of around 3300 mPa s. The results indicate that a homogeneous spinel coating with excellent adherence is obtained after two immersions and a calcination at 700 °C. Both structured catalysts are active in the steam reforming of ethanol at 650 °C. The system with a Co/Ce molar ratio of 3.7 exhibits the best performance with a high stability. A complete ethanol conversion and a hydrogen selectivity of around 95% are obtained in two reaction cycles of 36 h each with intermediate regeneration.

Geopolymer-hydrotalcite composites for CO2 capture

Supporting or shaping a porous powder is important for industrial applications as optimized structure with high mass transfer, low pressure drop and high mechanical and chemical stability can be obtained. A new class of geopolymer-hydrotalcite composites with suitable mechanical and thermal properties were conceived as shaped materials for CO2 adsorption applications at intermediate temperature (200–400 °C). Composite monoliths were produced mixing different commercial hydrotalcite-type (HyT) powders with a metakaolin-based geopolymer matrix with a molar ratio SiO2:Al2O3 = 4.0. The compressive strength at room temperature and 500 °C ranged between 10 and 35 MPa, mainly depending on HyT powder morphology and composite total porosity. The composites were characterized and tested in term of CO2 uptake. After calcination to convert HyT into an amorphous Mg:Al mixed solid oxide able to absorb CO2, the composites were tested in the CO2 adsorption at 200 °C, with cycles of adsorption/desorption performed with intermediate regeneration at 500 °C. CO2 adsorption capacity was in the range 0.375–0.461 mmol g−1 for HyT and between 0.109 and 0.145 mmol g−1 for composites, being 0.052 mmol g−1 the value for the geopolymer matrix. A partial deactivation of the HyT phases was also detected.

Supercritical heterogeneous nanostructure of fluids. Part 2. Its potential impact on creation of coupled stirlings with intermediate regeneration of heat

Supercritical heterogeneous nanostructure of fluids. Part 2. Its potential impact on creation of coupled stirlings with intermediate regeneration of heat

Dispersão de sementes e densidade populacional de Psychotria nuda (Rubiceae) em fragmento urbano de Floresta Ombrófila Densa de Terras Baixas no sul do Brasil

O presente trabalho objetivou reconhecer os agentes dispersores de Psychotria nuda num fragmento de Floresta Atlântica e estimar a sua densidade populacional. A área de estudo compreende um fragmento de floresta ombrófila em estádio médio de regeneração. A densidade populacional foi estimada em área de 1 ha. O padrão de distribuição da espécie foi determinado pelo índice de Morisita. Vinte indivíduos adultos foram observados para determinação de dispersores e mais dez para avaliar a eficácia do tipo de dispersão mediante marcação de frutos e instalação de redes coletoras. Em 1 ha foram registrados 1.131 indivíduos. O índice de Morisita encontrado para a população foi de 1,317, sinalizando padrão agregado de distribuição. Os resultados obtidos para a dispersão mostraram que a barocoria é mais frequente que a zoocoria. Foi registrada apenas Tachyphonus coronatus (tiê-preto) como ave dispersora de P. nuda. Conclui-se que o padrão de distribuição agregado encontrado pode estar relacionado com a falta de um agente dispersor mais eficiente quando comparado à dispersão barocórica, o que justifica o padrão de distribuição agregado. Em termos populacionais, a espécie apresenta uma taxa balanceada entre recrutamento e morte de indivíduos, garantindo sua ocorrência no fragmento florestal.

Influence of forest gaps on the density of cedar population in Silveira Martins-RS

The objective of this study is to analyze the influence of gaps on the density of cedar population ( Cedrela fissilis Vell.) and characterize the total diameter distribution and size class of this species. The study area is located in the municipality of Silveira Martins (state of Rio Grande do Sul), where a census was conducted by walking through 5.54 hectares. The area was divided and characterized into A (0.36 ha), more intensive use of soil; B (0.10 ha), gap with a radius of approximately 17.5 m; C (0.08 ha), gap with radius of approximately 16 m; and D (5.0 ha), intermediate regeneration. All cedar individuals with a total height greater than 15 cm were measured and classified as adults (diameter at breast height - DBH > 10 cm), young (0 < DBH <10 cm), and seedlings (total height - Ht < 1.30 m). The density per area and the Chi-square test for the different areas were calculated. In addi­tion, a diameter distribution histogram was constructed for each size class and area. The negative exponential shape of diametric distribution histograms evidences that the areas with gaps present a higher frequency of young individuals and seedlings; however, there was no difference between the gaps (areas B and C) and the area at an initial regeneration stage (area D).

Evaluation of adsorbent and ion exchange resins for removal of organic matter from petroleum refinery wastewaters aiming to increase water reuse

The oil refinery industry seeks solutions to reduce its water uptake and consumption by encouraging the reuse of internal streams and wastewater from treatment systems. After conventional treatment the petroleum refinery wastewater still contains a considerable quantity of recalcitrant organics and the adsorption on activated carbon is currently used in Brazilian refineries, although it is still expensive due to the difficulty of its regeneration. This study evaluated the use of adsorbent and ion exchange resins for the removal of organic matter from refinery wastewater after conventional treatment in order to verify its feasibility, applying successive resin regenerations and comparing the results with those obtained for activated carbon process. Adsorption isotherms experiments were used to evaluate commercial resins, and the most efficient was subjected to column experiments, where absorbance (ABS) and total organic carbon (TOC) removal were measured. The adsorption isotherm of the best resin showed an adsorptive capacity that was 55% lower than that of activated carbon. On the other hand, the column experiments indicated good removal efficiency, and the amount of TOC in the treated wastewater was as good as has been reported in the literature for activated carbon. The regeneration efficiency of the retained organics ranged from 57 to 94%, while regenerant consumption ranged from 12 to 79% above the amount recommended by the resin supplier for the removal of organic material from natural sources, showing the great resistance of these recalcitrant compounds to desorption. Finally, an estimate of the service life of the resin using intermediate regeneration conditions found it to be seven times higher than that of activated carbon when the latter is not regenerated.

Structure-activity relationships of Ni-Cu/Al2O3 catalysts for γ-valerolactone conversion to 2-methyltetrahydrofuran

The activity of a series of impregnated Ni-Cu/Al2O3 catalysts was evaluated for the production of 2-methyltetrahydrofuran (MTHF) from γ-valerolactone using 2-butanol as solvent. These catalysts evidenced that their activities depend more on the metal phase nature then on the metal sites dispersion, achieving three times higher Normalized MTHF Productivity (NMP) the samples with the highest amounts of the Ni-Cu alloy. In addition, the activity of those high Ni-Cu alloy containing samples showed to be limited by their low surface acidity. The promotion of the alloy formation, acidity and metal-acid sites proximity was achieved by a co-precipitation method. This new catalyst, calcined and reduced at 450°C, allows a MTHF yield of 64% after 5h. The tested catalysts showed deactivation by carbon deposition which could be overcome by intermediate regeneration between runs. The best catalyst showed stable>54% MTHF yield for three consecutive runs.

Beneficial effects of calcium chloride on glucose dehydration to 5-hydroxymethylfurfural in the presence of alumina as catalyst

Aluminas with different acid-base properties (acid, neutral and basic) have been characterized by using XRD, N2 sorption at −196°C, XPS and NH3-TPD, and tested for the dehydration of glucose to 5-hydroxymethylfurfural (HMF). Under the operating conditions used, the acid alumina showed the highest total acidity and the best catalytic performance, but the HMF yield hardly exceeded 20% since γ-Al2O3 apparently favored the secondary reactions. The presence of CaCl2 in the reaction medium notably improved the catalytic performance, even at very short reaction times, due to the interaction between Ca2+ ions and glucose molecules, which favors the α-d-glucopyranose formation, thus enhancing glucose conversion and HMF yield up to 96% and 52%, respectively, at 175°C after 15min in presence of 0.65 gCaCl2·gaq.sol.−1 and acid γ-Al2O3 as catalyst. The isomerization of glucose to fructose and subsequent dehydration to HMF does not seem to take place when CaCl2 is present in the reaction medium, as inferred from 1H NMR spectroscopy. Moreover, the catalyst was reused at least for three runs maintaining the catalytic activity, without an intermediate regeneration step.

Glucose isomerisation into fructose over magnesium-impregnated NaY zeolite catalysts

The performance of magnesium-impregnated NaY zeolite catalysts for the glucose isomerisation into fructose at 100°C has been evaluated. Although crystallinity and textural properties of the zeolites are reduced through Mg addition, glucose conversion improves (6–49%) by increasing magnesium content (0–15wt.%) due to an increase of the number of basic sites. Conversely, selectivity to fructose drops (96–66%). Nevertheless, good fructose yields were still reached with 10 and 15wt.% of magnesium (about 32%), being similar or even higher than those found for a commercial hydrotalcite and a pure magnesium oxide. Catalysts lose performance through carbon retention and cations leaching. Deactivation of magnesium-based zeolites was further investigated by consecutive reaction runs. If no regeneration of the catalyst is performed, the activity of the zeolites decreases mainly as a result of cations leaching, the effect reducing with the number of runs. Regeneration allows the catalyst to recover almost totally its initial activity. Interestingly, used samples show higher fructose selectivity due to the additional pore opening resulting from cations leaching and/or carbon removal. Cations leaching results in a homogeneous catalytic reaction which is most significant for the highest magnesium content. Magnesium-based NaY zeolites are revealed as potential catalysts for glucose isomerisation into fructose with high fructose productivities and good performance in consecutive reactions combined with intermediate regeneration.

SOIL SEED BANK IN SEASONAL SEMIDECIDUOUS FOREST AND ABANDONED PASTURE

ABSTRACT The objective of this study was to characterize the seed bank in the soil of different successional stages of Seasonal Semideciduous Forest and abandoned pasture in order to understand the natural regeneration potential of these areas. At each successional stage, 30 samples of soil were collected in the rainy and dry seasons to evaluate the qualitative heterogeneity of the forest, at the regeneration stage (FEA) forest, intermediate regeneration stage forest (ISF) and pasture (PAS). The species were classified according to the life form, successional group and dispersion syndrome. The number of individuals germinated was significantly higher (p &lt; 0.001) in the ISF and in the rainy season (15,949 individuals). Richness was higher in the pasture area (79 species), with a significant difference only between the environments. Most species are herbaceous (49.5%), pioneers (76.5%) and zoocory was the main dispersion syndrome (49% of species). The results show that seed bank in the fragment of the regeneration advanced stage forest presents the highest resilience potential, since it is formed by different life forms and, mainly, by early and late secondary species.

Forest regeneration affects dung beetle assemblages (Coleoptera: Scarabaeinae) in the southern Brazilian Atlantic Forest

The Brazilian Atlantic Forest is one of the most diverse environments, but it is also one of the most threatened areas in terms of loss of biodiversity and ecosystem services. Assessment of changes in the community structure during the recovery of forests can be performed using indicator organisms. Dung beetles perform several ecological functions and show high sensitivity to natural and anthropogenic environmental changes. This study aimed to investigate the effect of regeneration time of Atlantic Forest sites on structure of Scarabaeinae assemblages. We sampled dung beetles using ten baited pitfall traps per site, in six sites grouped into three classes of forest regeneration time (~30, ~60 and >80 years) in the southern Brazilian Atlantic Forest, during January 2015. A total of 520 individuals belonging to 16 species and nine genera of dung beetles were sampled. Rarefied species richness did not differ between sites with different regeneration times. Average species richness and abundance of Scarabaeinae was smaller in areas of shorter recovery time. True alpha diversity was higher in areas with intermediate recovery whereas Shannon diversity showed higher values in areas of shorter recovery. Approximately 29 % of the variation in abundance data of Scarabaeinae was explained by environmental variables, with one-third of this variation explained also by spatial predictors. External factors such as landscape management and farming practices in the surroundings must be taken into consideration in management plans and the management of natural areas for the recovery of biodiversity in the Atlantic Forest. These external factors can considerably affect the structure of communities and lead to scenarios of greater diversity in intermediate regeneration sites due to the heterogeneity of the landscape.

Carbon and nutrient fluxes through litterfall at four succession stages of Caatinga dry forest in Northeastern Brazil

Knowledge about litterfall and its nutrient fluxes is important for understanding ecosystem dynamics, especially in regards to vegetation at different succession stages. Regenerating vegetation represents a large proportion of tropical forests, such as the caatinga dry forest in NE Brazil, which is heavily used for fuel wood and slash-and-burn agriculture. In the present study we measured litterfall for 2 years in four regeneration stages of caatinga: recently abandoned pasture, 15-, 37-, and 57-years (mature caatinga) of regeneration. The lowest litter C fluxes were observed in pasture sites but the highest fluxes occurred in the intermediate regeneration stages (15 and 37 years of regeneration) than in the mature caatinga. The 15-year site had the highest concentrations and the greatest fluxes of nitrogen and phosphorus. Nutrient concentrations in litter were in the range of those found in other dry forests, but the fluxes were lower. The high N:P concentration ratios indicate that P is a limiting nutrient in this ecosystem. The proportion of total litterfall C fluxes relative to total C stocks in the ecosystem decreased consistently with succession age, but annual net C accumulation in the ecosystem increased with succession age. The results suggest that litterfall in earlier regeneration stages is more strongly affected by rainfall variation than mature vegetation, but these patterns need to be further investigated for longer periods. This higher stability of mature ecosystems could be important in face of the expected higher climatic variability in the future.

Increased Recovery of Green Doubled Haploid Plants from Barley Anther Culture

ABSTRACTAlbinism is a major limitation in the production of doubled haploid plants in cereals. As this trait is partly genetically controlled, the culture method has to be adapted to the plant genotype to reduce albinism. We have improved green plant recovery in the Northern barley (Hordeum vulgare L.) spring cultivar Mitja from 6 to 42% by altering the culture method and composition of the culture media. In a new three‐step protocol, the addition of casein hydrolysate to an intermediate regeneration medium gave the highest number of green plants. The shoot and root growth medium used for germinated embryos was superior to the standard media reported in the literature for root formation and shoot growth. Our modified method has merit for testing with other recalcitrant genotypes in anther and isolated microspore cultures.