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An increasing share of dispatchable renewable generation is required to achieve energy decarbonisation goals and ensure a reliable supply to power grids. Concentrating solar power (CSP) plants hybridised with biomass boilers are promising alternatives to replace part of the peaking and baseload power generated from fossil fuel-based systems. This paper includes data related to the design variables, equations, valuation parameters and detailed results that support the research article "Market profitability of CSP-Biomass hybrid power plants: Towards a firm supply of renewable energy." The profitability assessment is based on integrating the hourly variation of electricity prices in the Iberian day-ahead market (MIBEL) to the results of the techno-economic model through a novel economic metric named Profitability Factor. In addition, stochastic simulations were conducted to capture the uncertainty of relevant input variables on the profitability of the proposed hybrid plants. The resulting datasets presented in this paper will provide insights for researchers looking to address the economic performance of renewable generation concepts from a market profitability approach. Furthermore, the data can be used by investors and policymakers to better understand the risks and implications associated with the profitability potential of these systems.

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Membrane filtration processes have been used to treat landfill leachate. On the other hand, closing the leachate treatment loop and finding a final destination for landfill leachate membrane concentrate (LLMC) - residual stream of membrane systems - is challenging for landfill operators. The re-introduction of LLMC into the landfill is typical; however, this approach is critical as concentrate pollutants may accumulate in the leachate treatment facility. From that, leachate concentrate management based on resource recovery rather than conventional treatment and disposal is recommended. This work comprehensively reviews the state-of-the-art of current research on LLMC management from leachate treatment plants towards a resource recovery approach. A general recovery train based on the main LLMC characteristics for implementing the best recovery scheme is presented in this context. LLMCs could be handled by producing clean water and add-value materials. This paper offers critical insights into LLMC management and highlights future research trends.

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This study evaluates the economic viability of sheep finishing systems on irrigated Tamani grass pasture under continuous stocking, using castor bean cake. Four production systems were simulated: sheep supplemented with soybean meal on pasture fertilized with urea (SMUR), sheep supplemented with detoxified castor bean cake on pasture fertilized with urea (CCdUR), sheep supplemented with soybean meal on pasture fertilized with in natura castor bean cake (SMCC) and sheep supplemented with detoxified castor bean cake on pasture fertilized with in natura castor bean cake (CCdCC). A minimum unit of 3 hectares and an average slaughter weight of 28 kg were considered. A minimum selling price, at which the least profitable system would become profitable, was stablished: US$ 2.38 and US$ 4.45/kg per kilogram of body weight and carcass weight equivalent, adopting a minimum rate of return of 3.5% per year, based on the Selic rate. The costs for organic fertilization were 46.01% higher than in systems using chemical fertilization. The selling of live animals was not attractive in any of the systems evaluated, and the opposite was observed for the selling of carcasses and non-carcass components. System SMUR proved to be more profitable, with a gain of US$ 0.53 per kg carcass.

Objetivou-se avaliar a economicidade de sistemas de terminação de ovinos em pastagem irrigada de capim-tamani sob lotação contínua, utilizando torta de mamona. Foram simulados quatro sistemas de produção: ovinos suplementados com farelo de soja e o pasto adubado com ureia (FSUR), ovinos suplementados com torta de mamona destoxificada e o pasto adubado com ureia (TMdUR), ovinos suplementados com farelo de soja e o pasto adubado com torta de mamona in natura (FSTM) e ovinos suplementados com torta de mamona destoxificada e o pasto adubado com torta de mamona in natura (TMdTM). Foi considerada a unidade mínima de 3 hectares e determinado um peso médio ao abate de 28 kg de peso corporal. Estabeleceu-se um preço de venda mínimo, no qual o sistema de criação menos lucrativo se tornasse rentável de 2,38 e 4,45 dólares por quilograma de peso corporal e por equivalente de peso da carcaça, dotando uma taxa mínima de atratividade de 3,5% ao ano, com base na taxa Selic. Os custos com adubação orgânica, em média, são 46,01% superiores aos sistemas que utilizam adubação química. A venda de animais vivos não é atrativa em nenhum dos sistemas avaliados, sendo o contrário observado para a comercialização de carcaças e dos não componentes da carcaça de ovinos. O sistema de produção FSUR se mostrou mais lucrativo, com ganho de US$ 0.53 centavos por kg de carcaça.

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To verify the potential of metabolites extracted from Rhizobium tropici to trigger the priming of defense responses in cruciferous plants, we analyzed the expression of defense-related genes by qRT-PCR. Brassica oleracea var. capitata, susceptible to Xanthomonas campestris pv. campestris, were grown in greenhouse conditions. At 18 days after sowing, plants were inoculated with 1 mL of 1% concentrated metabolites produced by R. tropici (CM-RT) in the root. In a second experiment, leaves were sprayed with 1 mL of a solution containing 1% CM-RT. Aerial and root tissue were collected separately at 0 (non-treated control condition), 24, and 48 h after application, submitted to RNA extraction and gene expression analysis by qRT-PCR. The results showed that, after root treatment with CM-RT, most evaluated genes were upregulated at 24 h after application and downregulated at 48 h after application in roots, while in leaves, genes were downregulated both at 24 and 48 h after application. On the other hand, leaf treatment with CM-RT showed that most evaluated genes in leaves and roots were upregulated at 24 and 48 h after application. These results indicate that the effect of CM-RT applied in roots seems restricted to the applied region and is not sustained, while the application in leaves results in a more systemic response and maintenance of the effect of CM-RT for a longer period. The results obtained in this study emphasize the biotechnological potential of using metabolites of R. tropici as an elicitor of active defense responses in plants.

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In this study, we aimed to apply an untargeted LC/QTOF-MS analysis for the identification of compounds that positively and negatively affect the acceptance of coffee beverages from liquid coffee concentrates (CLCs) before and after storage. The metabolomic results were integrated with physicochemical and sensory parameters, such as color, pH, titratable acidity, and oxygen contents, by a bootstrapped version of partial least squares discriminant analysis (PLS-DA) to select and classify the most relevant variables regarding the rejection or acceptance of CLC beverages. The OPLS-DA models for metabolite selection discriminated between the percent sensory acceptance (the Accepted group) and rejection (the Rejected group). Eighty-two molecular features were considered statistically significant. Our data suggest that coffee sample rejection is associated with chlorogenic acid hydrolysis to produce ferulic and quinic acids, consequently generating methoxybenzaldehydes that impact the perceived acidity and aroma. Furthermore, acceptance was correlated with higher global scores and sweetness, as with lactones such as feruloyl-quinolactone, caffeoyl quinolactone, and 4-caffeoyl-1,5-quinolactone, and significant oxygen levels in the headspace.

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The objective of this research was to evaluate the sensory expectation and buying intention of consumers from different Brazilian regions for skyr-type yogurt based on the colors and sweetener on its label. Ten images of skyr mango yogurt labels were created varying in color (orange, white, yellow, blue, and green) and sweetening agent (sucrose and natural sweeteners). Consumers (151 consumers) were asked to rate their expectation for the ideal of sweetness, healthiness, acceptance, and buying intention. Labels containing the information "sweetened with sucrose" had a higher percentage of expectation of sweeter than ideal. Label color and sweetening agent had a significant effect on the expectation of acceptance, with a higher percentage for yogurt sweetened with natural sweeteners. There were not statistical differences (p > 0.05) between the labels regarding expected healthiness. Results also showed that consumers had a low level of familiarity with skyr-type yogurts, but it is presented as a healthy yogurt alternative.

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Our objective was to elaborate lactose-free Dulce de leche (DL) and evaluate the influence of the hydrolysis of this sugar on the attributes of the products. Fluid milk used was divided into two portions and, in one of them, enzymatic hydrolysis of lactose was carried through. Next, the homogenization of milk was performed at 20 MPa. Four different treatments were studied. The final products were evaluated in relation to their composition and physico-chemical characteristics. The main results show that the homogenized lactose-free DL obtained a higher concentration of free 5-Hydroxymethylfurfural (HMF) (133.77 ± 3.42 µmol l-1). Consequently, browning was more intense due to Maillard Reaction. Texture parameters were higher (1611.00 ± 598.78 g hardness and 19.52 ± 2.46 g gumminess) when compared to the homogenized traditional product (28.45 ± 1.16 µmol l-1 free HMF, 437.17 ± 279.3 g hardness, and 406.20 ± 311.69 g gumminess). Lactose-free products are in high demand by consumers; however, the results of this work highlight the challenges to properly control the browning and the texture parameters of DL.

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Dulce de leche, a concentrated dairy product with high added value, is an essential product of Brazilian culture. However, with a competitive market among economic blocks, it is important to know if the country of origin influences the perception of consumers and the intention to purchase a product, aiming to boost production in the domestic market. This study aimed to assess the impact of different levels of ethnocentrism on the consumer perception and buying behavior toward dulce de leche (DL) from other countries (Argentina, Uruguay, and Brazil). Through an online survey, participants' demographic data (n = 224) was collected. Then they were encouraged to identify the purchase motivation using the Hard Laddering (HL) methodology and to assess the consumer's level of ethnocentrism (CE) with CESTSCALE. Three distinct groups were identified: high, moderate, and low ethnocentric. Consumers with high CE declared themselves conservative, with a more significant number of self-employed workers, and prefer and always buy national products. This group had a robust dominant chain only for the national product, highlighting the flavor and quality, and values ​​of nationalism and solidarity with local producers. On the other hand, consumers with low CE were self-declared liberal and had a higher level of education. They demonstrated significantly more favorable attitudes and intentions towards purchasing imported products due to improved quality, although patriotic behavior was also evident. We conclude that with CETSCALE, it was possible to identify that the sample of the Brazilian population studied has different levels of CE, which strongly impact the purchase attitude of products, especially the imported ones. However, it was only through the HL technique that it was noticed that, in addition to its intrinsic characteristics, patriotism is an important factor for the product and can be used as a sales motivator. This study demonstrated the importance of promoting the development of DL in the domestic market and encourage aspects of the origin, as they are fundamental in the choice of this product by the consumer, which helps local industries.

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Concentrated liquid coffees (CLCs) refer to stored extracts stable at environmental temperature, used as ingredients in the retail market. Their low chemical stability affects the sensory profile. This study was performed in two CLCs, one without additives (BIB) and another with a mix of sodium benzoate and potassium sorbate additives (SD), stored at 25 °C for one year. Quantitative-Descriptive (QDA) and discriminant analyses permitted identifying the critical sensory attributes and their evolution over time. The concentrate without additives presented an acceptance limit of 196 days (evaluated at a 50% acceptance ratio), while the additives increased the shelf life up to 226 days (38.9% improvement). The rejection was related to a decreased aroma, increased acidity, and reduced bitterness. A bootstrapped feature selection version of Partial Least Square analysis further demonstrated that reactions of 5-caffeoylquinic acid (5CQA) and 3,5-dicaffeoylquinic acid (3,5diCQA) could cause changes in the aroma at the first degradation stage. In the following stages, changes in fructose and stearic acid contents, a key indicator of acceptance for both extracts possibly related to non-enzymatic reactions involving fructose and other compounds, might affect the bitterness and acidity. These results provided valuable information to understand flavor degradation in CLCs.

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Physalins are seco-steroids with a variety of pharmacological activities already described. In this study the pharmacological properties of a standardized concentrated ethanolic extract from Physalis angulata (CEEPA), rich in physalins B, D, F and G, were studied in models of pain and inflammation in mice. Inflammatory mediators were measured by radioimmunoassay and Real-Time PCR in mice paws after the CFA stimuli. Systemic administration of CEEPA produced antinociceptive effect on the writhing test and formalin test. In the writhing test, physalins B, D, F and G showed that the antinociceptive effect of CEEPA is more potent than that of these purified compounds. In addition, CEEPA reduced the levels of TNF-α, IL-1ß, COX-2 and iNOS mRNA in the CFA-induced paw inflammation. Likewise, CEEPA decreased the TNF-α, IL-1ß and PGE2 paw levels. In conclusion, CEEPA induces antinociceptive and anti-inflammatory effects, with improved pharmacological potency relative to pure physalins, associated to modulation of cytokine and cyclooxygenase pathways.

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Pluronic® F127 micellar hydrogels are of growing interest to the biomedical field due to their versatility as drug delivery systems. Pluronic® F127 is a symmetric and amphiphilic triblock copolymer which in aqueous medium self-assembles into micelles that pack togetherwith increasing temperature or concentration, leading to non-flowable hydrogels. The microstructure of these hydrogels is usually investigated by small-angle X-ray scattering, which is not a readily available technique. Conversely, cryo-TEM is a widespread technique used for investigating the morphology of aqueous systems. In the case of Pluronic® F127 micellar systems, the elevated viscosity poses a significant challenge for specimen preparation and, consequently, for cryo-TEM observation. Herein, we show a trustworthy, inexpensive and readily available methodology for preparing specimens of highly viscous micellar solutions and non-flowable hydrogels using an automated vitrification system. With this methodology we were able to visualize not only the morphology of individual Pluronic® F127 micelles -but also the supramolecular structure evolution as a function of concentration. This methodology opens up a wide range of opportunities for hydrogel characterization, although additional systematic studies might be required in order to optimize and replicate it for similar systems.

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The objective of this study was to evaluate the effect of the initial microbial load, temperature and contact time on the biofilm formation of Alicyclobacillus acidoterrestris on stainless steel and natural food-grade rubber using orange juice as culture medium. The low initial load of A. acidoterrestris (2 log CFU/mL) led to biofilm formation on the stainless steel surface after 48 h of contact at 28 ºC and after 24 h at 45 ºC, and on natural food-grade rubber surface after 48 h of contact at both temperatures. The high initial microbial load (5 log CFU/mL) led to biofilm formation on stainless steel after 4 h of contact at 28 °C and 45 °C, while biofilm was formed on natural food-grade rubber after 8 h of contact at 28 °C and 4 h at 45 °C. The microbial load also affected the presence of spores in biofilm, which was observed on both surfaces only at high initial loads of A. acidoterrestris.(AU)

O objetivo deste estudo foi avaliar o efeito da carga microbiana inicial, temperatura e tempo de contato na formação de biofilme de Alicyclobacillus acidoterrestris em aço inoxidável e borracha natural de qualidade alimentar utilizando suco de laranja como meio de cultura. A baixa carga inicial de A. acidoterrestris (2 log UFC/mL) levou à formação de biofilme na superfície do aço inoxidável após 48 h de contato a 28 ºC e após 24 h a 45 ºC, e na superfície natural de borracha de qualidade alimentar após 48 h de contato nas duas temperaturas. A alta carga microbiana inicial (5 log UFC/mL) levou à formação de biofilme em aço inoxidável após 4 h de contato a 28 °C e 45 °C, enquanto o biofilme foi formado em borracha natural de qualidade alimentar após 8 h de contato a 28 °C e 4 h a 45 °C. A carga microbiana também afetou a presença de esporos no biofilme, o que foi observado em ambas as superfícies apenas com altas cargas iniciais de A. acidoterrestris.(AU)

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ABSTRACT: The objective of this study was to evaluate the effect of the initial microbial load, temperature and contact time on the biofilm formation of Alicyclobacillus acidoterrestris on stainless steel and natural food-grade rubber using orange juice as culture medium. The low initial load of A. acidoterrestris (2 log CFU/mL) led to biofilm formation on the stainless steel surface after 48 h of contact at 28 ºC and after 24 h at 45 ºC, and on natural food-grade rubber surface after 48 h of contact at both temperatures. The high initial microbial load (5 log CFU/mL) led to biofilm formation on stainless steel after 4 h of contact at 28 °C and 45 °C, while biofilm was formed on natural food-grade rubber after 8 h of contact at 28 °C and 4 h at 45 °C. The microbial load also affected the presence of spores in biofilm, which was observed on both surfaces only at high initial loads of A. acidoterrestris.

RESUMO: O objetivo deste estudo foi avaliar o efeito da carga microbiana inicial, temperatura e tempo de contato na formação de biofilme de Alicyclobacillus acidoterrestris em aço inoxidável e borracha natural de qualidade alimentar utilizando suco de laranja como meio de cultura. A baixa carga inicial de A. acidoterrestris (2 log UFC/mL) levou à formação de biofilme na superfície do aço inoxidável após 48 h de contato a 28 ºC e após 24 h a 45 ºC, e na superfície natural de borracha de qualidade alimentar após 48 h de contato nas duas temperaturas. A alta carga microbiana inicial (5 log UFC/mL) levou à formação de biofilme em aço inoxidável após 4 h de contato a 28 °C e 45 °C, enquanto o biofilme foi formado em borracha natural de qualidade alimentar após 8 h de contato a 28 °C e 4 h a 45 °C. A carga microbiana também afetou a presença de esporos no biofilme, o que foi observado em ambas as superfícies apenas com altas cargas iniciais de A. acidoterrestris.

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The objective of the present study was to evaluate, through a meta-analysis, the effects of feeding systems and tocopherol levels found in the diet of lambs on qualitative characteristics of their meat. A search of the computerised literature in Science Direct databases, PubMed, Scopus, and SciELO virtual library was carried out to select works that evaluated the quality of lamb meat. As a first requirement for inclusion in the meta-analysis, articles were selected with the keywords "tocopherol", "meat", and "lamb". The variables extracted from the articles were classified according to the type of feeding system and tocopherol level in the diet of lambs. Production systems alter the qualitative characteristics of meat. Lambs raised exclusively on pasture present a higher tocopherol concentration in their meat, a lower omega 6:omega 3 ratio, a lower omega 6 concentration, and a higher conjugated linoleic acid concentration. Regardless of the dietary systems, when we classify the tocopherol levels of lamb diet, the tocopherol concentration and fatty acid level are altered by tocopherol levels in the diet. The lower tocopherol level in the diet results in meat with lower tocopherol concentration and with greater propensity to lipid oxidation.(AU)

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Con el objetivo de evaluar el efecto antihelmíntico de los taninos concentrados (TC) se realizó su estudio sobre los nematodes gastrointestinales (NGI) en caprinos y ovinos. Se asignaron dos grupos compuestos de 6 cabras y 4 ovejas cada uno en pastoreo de alfalfa; un grupo sin tratamiento (GST) suplementado con 500 g de maíz molido y otro (GTC) con igual suplemento más la adición diaria de 25 g de TC. Cada dos semanas durante 3 meses se realizaron conteos de huevos de NGI por gramo de heces (hpg) y coprocultivos. Además, se registró la condición corporal (CC) y el grado de FAMACHA. Los hpg fueron bajos y similares en los primeros tres muestreos (= 507,4 GTC y 351,4 GST), luego los hpg del GST disminuyeron resultando inferiores al GTC, pero sin diferencias significativas (p<0,096) entre grupos, entre fechas de muestreo (p<0,66) ni entre la interacción grupo por muestreo (p<0,99). En los coprocultivos se observó, un predominio de Haemonchus (64,6%) para GTC y Trichostrongylus (45,8%) para GST; en todos se recuperó en bajo porcentaje Teladorsagia. Los datos obtenidos del score Famacha no mostraron diferencias significativas (p<0,46), promediando 2,11 ± 0,66 para el GTC y 1,83 ± 0,71 de score para el GST. Los promedios de CC fueron 2,93 ± 0,65 y 3,16 ± 0,54 respectivamente para el GTC y GST, sin diferencias significativas (p< 0,42). Bajo las condiciones del presente estudio con una baja infestación, 25g de taninos concentrados en 500g de maíz representó una dosis sin efecto antihelmíntico.

In order to evaluate the anthelmintic effect of condensed tannins (TC), a study was made to evaluate its effect on gastrointestinal nematodes (NGI) in goats and sheep. Two groups of 6 goats and 4 sheep grazing Lucerne were assigned; one group without treatment (GST) was daily supplemented with ground corn (500 g), while the other group (GTC) with the same diet and the inclusion of 25 g of TC. Faecal nematode egg counts (epg) and coprocultures were made every two weeks for 3 months. In addition, FAMACHA technique and body condition score (CC) were recorded. The epg were similar in the first three samplings (= 507.4 GTC y 351.4 GST), then the GST epg decreased being lower than those of the GTC, but without significant differences (p <0.096) between groups, between sampling dates (p <0.66) not even in group per sampling date interaction (p <0.99). From faecal cultures Haemonchus (64.6%) predominated in GTC and Trichostrongylus (45.8%) in GST; Teladorsagia was recovered under low percentages. FAMACHA score did not show differences (p <0.46) between groups, averaging 2.11 ± 0.66 and 1.83 ± 0.71 respectively for GTC and GST. The CC averages were 2.93 ± 0.65 and 3.16 ± 0.54 respectively for GTC and GST and differences weren't found (p <0.42). It concluded that under the conditions of this study with low NGI burdens, the condensed tannin dose of 25g in 500g of corn represents a low dose without anthelmintic effect.

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Water with high concentration of nitrate may cause damage to health and to the environment. This study investigated how concentration, current density, flow, pH, the use of Pd/In catalyst and operating mode (constant current density and constant cell potential) have an influence in the electrochemical reduction of nitrate and in the formation of gaseous compounds using copper electrode. Experiments were performed in two-compartment electrolytic cells separated by a cationic membrane with nitrate model solutions prepared as a surrogate of concentrated brines from membrane desalination plants. The results show that the electroreduction process has potential for reduction of nitrate and that it is influenced by the operational conditions. The best conditions found for the treatment - with satisfactory reduction of nitrate, formation of gaseous compounds and reproducibility - were at nitrate concentrations of 600 and 1000 mg L-1, current density of 1.1 mA cm-2 and without pH control, since in these conditions the production of gaseous compounds is higher than the production of nitrite. When Pd/In catalyst was used, the nitrate reduction was 50% after 6 h of experiment and the predominant product were gaseous compounds. When compared to the experiment without the catalyst, the arrangement with Pd/In was the most efficient one.

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OBJECTIVE: Glucose conversion into disaccharides was performed with ß-glucosidases from Prunus dulcis (ß-Pd), Aspergillus niger (ß-An) and A. awamori (ß-Aa), in reactions containing initial glucose of 700 and 900 g l-1. RESULTS: The reactions' time courses were followed regarding glucose and product concentrations. In all cases, there was a predominant formation of gentiobiose over cellobiose and also of oligosaccharides with a higher molecular mass. For reactions containing 700 g glucose l-1, the final substrate conversions were 33, 38, and 23.5% for ß-An, ß-Aa, and ß-Pd, respectively. The use of ß-An yielded 103 g gentiobiose l-1 (15.5% yield), which is the highest reported for a fungal ß-glucosidase. The increase in glucose concentration to 900 g l-1 resulted in a significant increase in disaccharide synthesis by ß-Pd, reaching 128 g gentiobiose l-1 (15% yield), while for ß-An and ß-Aa, there was a shift toward the synthesis of higher oligosaccharides. CONCLUSION: ß-Pd and the fungal ß-An and ß-Aa ß-glucosidases present quite dissimilar kinetics and selective properties regarding the synthesis of disaccharides; while ß-Pd showed the highest productivity for gentiobiose synthesis, ß-An presented the highest specificity.

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Along with the emerging needs of the dental patients, numerous techniques for oral tissue stimulation and regeneration were developed to be employed in the modern implant rehabilitation therapies. The Concentrated Growth Factors (CGF) are a relatively new therapeutic presidium that can be used for this purpose, enhancing the regenerative potential property of blood cells. Although literature presents numerous studies evaluating the CGF for their clinical uses and efficacy, data regarding their biological characteristics are very few. The present study evaluates and describes the CGF structural morphology by means of classical histological methods, using haematoxilin-eosin and azan mallory stains. A three layers organization with a fibrin complex network was noted, with blood corpuscular elements entrapped, especially in the most external layer. These descriptions enrich the knowledge about this new type of membrane, showing the bio-morphological side of the regenerative techniques. These findings will be useful in clinical practice for the choice of the most suitable technique in each implant rehabilitation.

Junto con las nuevas necesidades dentales de los pacientes, se han desarrollado numerosas técnicas para la estimulación y regeneración de los tejidos orales para ser empleadas en las modernas terapias de rehabilitación de implante. Los Factores de Crecimiento Concentrados (FCC) son relativamente una nueva alternativa terapéutica que pueden utilizarse para este propósito, mejorando la propiedad regenerativa potencial de las células de la sangre. A pesar de que la literatura presenta numerosos estudios que evalúan los FCC por sus usos clínicos y su eficacia, los datos relativos a sus características biológicas son muy escasos. El presente estudio evalúa y describe la morfología estructural de los FCC por medio de métodos histológicos tradicionales, utilizando hematoxilina-eosina y tinción de Azan Mallory. Se observó una organización en tres capas con una compleja red de fibrina, con elementos corpusculares de la sangre atrapados, especialmente en la capa más externa. Estas descripciones enriquecen el conocimiento acerca de este nuevo tipo de membrana, que muestra el lado biomorfológico de las técnicas regenerativas. Estos resultados serán de utilidad en la práctica clínica para la elección de la técnica más adecuada en los casos de rehabilitación con implantes.

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This work describes a procedure using the recently proposed standard dilution analysis (SDA) calibration method for the determination of As, Cr and Ni in concentrated HNO3 and HCl by inductively coupled plasma tandem mass spectrometry (ICP-MS/MS). Because of the low contaminant levels, and consequently low limits of detection required for these reagents (commonly used in trace element analysis and the semiconductor industry), samples were minimally diluted. The analysis of concentrated acids can result in matrix/transport effects, which may compromise accuracy in ICP-MS determinations. High-chlorine content samples are also challenging for As and Cr determination due to the formation of polyatomic species such as 40Ar35Cl+ and 35Cl16OH+, which overlap the only As isotope, 75As+, and the main Cr isotope, 52Cr+, respectively. The combination of SDA and ICP-MS/MS was evaluated to overcome matrix, transport and spectral interferences in order to increase accuracy, precision and sample throughput. The performance of SDA was compared with the traditional methods of external standard calibration (EC), internal standardization (IS), and standard additions (SA). The limits of detection for SDA were calculated as 6, 10, and 30ngL-1 for As, Cr, and Ni, respectively. Recoveries for spike experiments using the new method were in the 90-114% range for all analytes. The procedure described here provides similar or even better analytical performance in comparison with EC, IS and SA.

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The origin of life is a very rich field, filled with possibilities and ripe for discovery. RNA replication requires chemical energy and vesicle division is easy to do with mechanical energy. These requirements point to a surface lake, perhaps at some time following the period of concentrated cyanide chemistry that gave rise to nucleotides, amino acids and (maybe) fatty acids. A second requirement follows specifically from the nature of the RNA replication cycle, which requires generally cool to moderate temperatures for the copying chemistry, punctuated by brief periods of high temperature for strand separation. Remarkably, lakes in a geothermal active area provide just such a fluctuating temperature environment, because lakes similar to Yellowstone can be generally cool (even ice covered in winter), but they contain numerous hydrothermal vents that emit streams of hot water. Protocells in such an environment would occasionally be swept into these hot water streams, where the transient high temperature exposure would cause RNA strand separation. However, the protocells would be quickly mixed with surrounding cold water, and would therefore cool quickly, before their delicate RNA molecules could be destroyed by heat. Because of the combination of favorable chemical and physical environments, this could be the most likely scenario for the early Earth environment that nurtured the origin of life.

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