The Reactivity and Stability of Polyoxometalate Water Oxidation Electrocatalysts

This review describes major advances in the use of functionalized molecular metal oxides (polyoxometalates, POMs) as water oxidation catalysts under electrochemical conditions. The fundamentals of POM-based water oxidation are described, together with a brief overview of general approaches to designing POM water oxidation catalysts. Next, the use of POMs for homogeneous, solution-phasewater oxidation is described togetherwith a summary of theoretical studies shedding light on the POM-WOC mechanism. This is followed by a discussion of heterogenization of POMs on electrically conductive substrates for technologically more relevant application studies. The stability of POM water oxidation catalysts is discussed, using select examples where detailed data is already available. The review finishes with an outlook on future perspectives and emerging themes in electrocatalytic polyoxometalate-based water oxidation research

The Goldilocks principle in action: synthesis and structural characterization of a novel {Cu4(\u3bc3-OH)4} cubane stabilized by monodentate ligands

A {Cu4(\u3bc3-OH)4} compound, where four copper(II) and four \u3bc3-bridging oxygen atoms occupy alternate corners of a slightly distorted cube, has been prepared and structurally characterized. This species, formulated as [Cu4(\u3bc3-OH)4(Htmpz)8](ClO4)4\ub71.5Et2O (Htmpz = 3,4,5-1H-trimethyl pyrazole), can be classified as belonging to type I Cu4O4 cubane complexes, and is better described as two CuII\u2013(\u3bc-OH)2\u2013CuII units held together by four long Cu\u2013O bonds. The central distorted cubane core is stabilized by neutral monodentate ligands (Htmpz) and perchlorate anions, as demonstrated by single-crystal X-ray structure analysis. The title compound was obtained by hydrolysis of a dinuclear methoxo-bridged species, [Cu(\u3bc-OCH3)(Htmpz)2]2(ClO4)2, which was prepared by reaction of [Cu(Htmpz)4(ClO4)2] with methanol. All these reactions represent a nice example of the Goldilocks principle in action in coordination chemistry, since each single actor (solvent, counteranion, and ligand) has the \u201cjust right\u201d electronic, steric or coordinative properties which determine the fate of the final products

Peritonitis: laparoscopic approach

BACKGROUND: Laparoscopy has became as the preferred surgical approach to a number of different diseases because it allows a correct diagnosis and treatment at the same time. In abdominal emergencies, both components of treatment – exploration to identify the causative pathology and performance of an appropriate operation – can often be accomplished via laparoscopy. There is still a debate of peritonitis as a contraindication to this kind of approach. Aim of the present work is to illustrate retrospectively the results of a case-control experience of laparoscopic vs. open surgery for abdominal peritonitis emergencies carried out at our institution. METHODS: From January 1992 and January 2002 a total of 935 patients (mean age 42.3 ± 17.2 years) underwent emergent and/or urgent surgery. Among them, 602 (64.3%) were operated on laparoscopically (of whom 112 -18.7% – with peritonitis), according to the presence of a surgical team trained in laparoscopy. Patients with a history of malignancy, more than two previous major abdominal surgeries or massive bowel distension were not treated Laparoscopically. Peritonitis was not considered contraindication to Laparoscopy. RESULTS: The conversion rate was 23.2% in patients with peritonitis and was mainly due to the presence of dense intra-abdominal adhesions. Major complications ranged as high as 5.3% with a postoperative mortality of 1.7%. A definitive diagnosis was accomplished in 85.7% (96 pat.) of cases, and 90.6% (87) of these patients were treated successfully by Laparoscopy. CONCLUSION: Even if limited by its retrospective feature, the present experience let us to consider the Laparoscopic approach to abdominal peritonitis emergencies a safe and effective as conventional surgery, with a higher diagnostic yield and allows for lesser trauma and a more rapid postoperative recovery. Such features make Laparoscopy a challenging alternative to open surgery in the management algorithm for abdominal peritonitis emergencies

Phenology and phyllochron of seven strawberry cultivars grown in substrate and greenhouse in the Brazilian subtropics

Knowing the phenology and phyllochron of strawberry cultivars allows the establishment of phytotechnical managements aimed at enhancing the productive chain of this horticultural crop. Thus, the objective of this work was to investigate whether phenology and phyllochron differ among strawberry cultivars grown in substrate and greenhouse. The treatments were seven strawberry cultivars arranged in a randomized block design, with four replications. Leaf emission rate, occurrence and duration of phenological stages were evaluated. ‘Fronteras’ was considered the earliest to start fruiting, as it had the lowest phyllochron value, while ‘Albion’ was the latest. Through multivariate analysis, the formation of two groups among strawberry cultivars was observed according to their phenological characteristics. Group 1 gathered the five strawberry cultivars classified as having neutral-days in terms of flowering and group 2 was composed of the two short-day cultivars. It is concluded that, under the cultivation conditions of southern Brazil, ‘Fronteras’ is the earliest to start the fruit harvest, provided it is transplanted in May, and ‘Albion’ is the latest. Neutral-day cultivars have a shorter transplant cycle until the beginning of harvest, while short-day cultivars require a longer interval for this transition, with a prolonged vegetative period.Knowing the phenology and phyllochron of strawberry cultivars allows the establishment of phytotechnical managements aimed at enhancing the productive chain of this horticultural crop. Thus, the objective of this work was to investigate whether phenology and phyllochron differ among strawberry cultivars grown in substrate and greenhouse. The treatments were seven strawberry cultivars arranged in a randomized block design, with four replications. Leaf emission rate, occurrence and duration of phenological stages were evaluated. ‘Fronteras’ was considered the earliest to start fruiting, as it had the lowest phyllochron value, while ‘Albion’ was the latest. Through multivariate analysis, the formation of two groups among strawberry cultivars was observed according to their phenological characteristics. Group 1 gathered the five strawberry cultivars classified as having neutral-days in terms of flowering and group 2 was composed of the two short-day cultivars. It is concluded that, under the cultivation conditions of southern Brazil, ‘Fronteras’ is the earliest to start the fruit harvest, provided it is transplanted in May, and ‘Albion’ is the latest. Neutral-day cultivars have a shorter transplant cycle until the beginning of harvest, while short-day cultivars require a longer interval for this transition, with a prolonged vegetative period

Forms of application of nitrogen in different stages of the development of soybean culture / Formas da aplicação de nitrogênio em diferentes estádios do desenvolvimento da cultura da soja

In Brazil, inoculation with Bradyrhizobium japonicum and B. elkanii strains is the main form of Nitrogen (N) supply to soybean, but there are reports of the use of mineral N as a complement to biological fixation. The objective was to evaluate the effect of different forms and times of N application on the development and yield of soybean. The treatments include a control without N application and in all other treatments 10 kg ha-1 of N was applied, altering the time (V2, V4, R1 or R2) and the application form, namely, at sowing, broadcast on topdressing or by leaf spraying. The application of N provided an increase in leaf area, dry mass of shoot, number of nodules and dry mass of nodules in treatments with application of N at sowing and N at V2 on topdressing. For plant height, the treatment with N at V2 by leaf spraying was superior compared to control. The weight of one thousand seeds was not affected by N application. For grain yield the treatments with application of N by leaf spraying in V2 and R1 were highlighted. The greatest increase in grain yield on soybean is reached with leaf spraying at V2 stage

Water excess in different soils and sowing times for sunflower in the state of Rio Grande do Sul, Brazil

O objetivo deste trabalho foi identificar datas de semeadura com menor ocorrência média de dias com excedente hídrico para a cultura do girassol, e determinar a persistência de dias consecutivos com excedente hídrico ao se considerar a capacidade de armazenamento de água disponível de diferentes solos da região central do Rio Grande do Sul. O desenvolvimento da cultura e o aprofundamento do sistema radicular foram simulados de acordo com a soma térmica para 14 datas de semeadura, de agosto até meados de fevereiro, com dados de 1968 até 2011. A partir da capacidade de armazenamento de água disponível para as diferentes classes de solos da região, calculou-se o balanço hídrico sequencial diário para determinar os dias com excesso hídrico. Avaliou-se a ocorrência de dias com excesso hídrico em diferentes subperíodos de desenvolvimento da cultura, e procedeu-se à análise exploratória com gráficos box‑plot para determinação da persistência de dias consecutivos com excesso hídrico durante todo o ciclo da cultura. O excedente hídrico limita o cultivo de girassol em determinadas áreas e períodos na região central do Rio Grande do Sul. A persistência de dias consecutivos com excedente hídrico e a duração do ciclo de desenvolvimento da cultura são  influenciados pela data de semeadura.The objective of this work was to identify sowing dates with the lowest average occurrence of days with water excess for sunflower crop, and to determine the persistence of consecutive days with water excess considering the available water storage capacity of different soils of the central region of the state of Rio Grande do Sul, Brazil. Crop development and root system deepening were simulated based on thermal summation for 14 sowing dates, from August until mid‑February, with data from 1968 to 2011. From the available water storage capacity of the different soil classes of the region, the sequential daily water balance was calculated to determine the days with water excess. The occurrence of days with water excess was evaluated in different crop development sub‑periods, and exploratory analysis with box‑plot graphs was performed to determine the persistence of consecutive days with water excess during the crop cycle. Water excess limits sunflower cultivation in some areas and periods in the central region of the state of Rio Grande do Sul. The persistence of consecutive days with water excess and the duration of the crop development cycle are influenced by the sowing date

O óleo essencial de gengibre (Zingiber officinale Roscoe) e peptídeo sintetizado pelo Lactococcus lactis como agentes antimicrobianos contra Salmonella Enteretidis E Listeria monocytogenes / The essential oil of ginger (Zingiber officinale Roscoe) and peptide synthesized by Lactococcus lactis as antimicrobial agents against Salmonella Enteretidis and Listeria monocytogenes

As doenças transmitidas por alimentos (DTA) são responsáveis por enfermidades e morte em todo o mundo. Dentre os principais micro-organismos patogênicos envolvidos, destaca-se a Salmonella Enteretidis e Listeria monocytogenes. Os compostos naturais como óleo, extratos de plantas e peptídeos de origem microbiana podem apresentar atividade antimicrobiana contra bactérias, fungos e vírus. Neste sentido, o objetivo deste estudo foi avaliar a atividade antimicrobiana bem como a concentração inibitória mínima (CIM) do óleo essencial de gengibre (OG) e do peptídeo produzido pelo Lactococcus lactis (PP) contra S. Enteretidis e L. m onocytogenes. Para isto, utilizou-se o método de difusão em disco para avaliar a atividade antimicrobiana bem como a concentração inibitória mínima (CIM) do OG e PP contra S. Enteretidis e L. monocytogenes. Os tamanhos dos halos de inibição (mm) foram submetidos a análise de variância (ANOVA) e teste de Tukey, com nível de 95% de confiabilidade. O OG apresentou atividade antimicrobiana contra S. Enteretidis e L. monocytogenes, produzindo halos de inibição de 8,75 e 18,62 mm, respectivamente. O PP apresentou atividade antimicrobiana somente para L. monocytogenes, produziu halo de inibição de 21,5 mm. Não houve diferença significativa (p <0,05) entre os tamanhos de halos produzidos pela atividade antimicrobiana do OG e do PP contra L. monocytogenes. A CIM do OG foi de 250 e 0,48 µL.mL-1 contra S. Enteretidis e L. monocytogenes, respectivamente. Já a CIM do PP foi de 0,48 µL.mL-1 contra L. monocytogenes. O OG e o PP apresentaram ação antimicrobiana contra micro-organismos patogênicos e podem ser uma alternativa interessante na conservação de alimentos

Molybdopterin-Modeling: The Synthesis of Pterin Dithiolene Ligands

The synthesis of pterin-dithiolene ligands was achieved by employing the radical nucleophilic substitution, i.e. the so-called “Minisci- Reaction”1. This protocol was used for the first time by Professor W. Pfleiderer on pterin substrates2 and proved a powerful method for the preparation of 6 acyl-pterins in course of this work. Subsequent construction of the dithiolene ring facilitates the synthesis of pterin-dithiolene ligands with completely unprotected pterin moieti. The molybdenum cofactor is probably one of the most relevant discoveries in the recent history of pterin chemistry and biochemistry. Many efforts have been made for the preparation of compounds able to mimic the features of the Moco ligand system called "Molybdopterin". In fact, the study of MPT models enables a deeper understanding of the “mechanism of function” of this cofactor and most importantly, lays the foundation for a potential treatment for the Moco related diseases MoCOD and iSOD.Die Synthese von Pterin Dithiolenliganden erfolgte durch die Verwendung radikalischer und nukleophiler Substitution, der sogenannten „Minisci-Reaktion“.1 Professor W. Pfleiderer wendete erstmals diese Methoden im Zusammenhang mit Pterinsubstraten2 an, welche sich im Rahmen dieser Arbeit als leistungsstarke Methode zur Herstellung von 6 Acyl-Pterinen erwies. Der anschließende Aufbau des Dithiolenrings erleichterte die Synthese von Pterin Dithiolenliganden mit ungeschützten Pteringruppen . Der Molybdän-Cofaktor ist wahrscheinlich eine der relevantesten Entdeckungen in der jüngeren Geschichte der Pterin- und Biochemie. Es wurden bereits viele Anstrengungen unternommen, um Verbindungen herzustellen, die die Eigenschaften des Moco-Ligandensystems "Molybdopterin“ nachahmen können. Tatsächlich ermöglicht die Untersuchung von MPT-Modellen ein tieferes Verständnis des „Funktionsmechanismus“ dieses Cofaktors und legt vor allem die Grundlage für eine mögliche Behandlung der Moco-bezogenen Krankheiten MoCOD und iSOD.

The Reactivity and Stability of Polyoxometalate Water Oxidation Electrocatalysts

This review describes major advances in the use of functionalized molecular metal oxides (polyoxometalates, POMs) as water oxidation catalysts under electrochemical conditions. The fundamentals of POM-based water oxidation are described, together with a brief overview of general approaches to designing POM water oxidation catalysts. Next, the use of POMs for homogeneous, solution-phase water oxidation is described together with a summary of theoretical studies shedding light on the POM-WOC mechanism. This is followed by a discussion of heterogenization of POMs on electrically conductive substrates for technologically more relevant application studies. The stability of POM water oxidation catalysts is discussed, using select examples where detailed data is already available. The review finishes with an outlook on future perspectives and emerging themes in electrocatalytic polyoxometalate-based water oxidation research