The effectiveness of Soxhlet extraction as a simple method for GO rinsing as a precursor of high-quality graphene.

Graphite-oxide (GO) is a valuable compound produced by the chemical oxidation of graphite. The procedure for converting graphite into GO includes two steps: oxidation and subsequent rinsing. Proper rinsing is essential to obtain processable and applicable graphite-oxide. Traditionally, the rinsing involves filtration or centrifugation; both processes are extremely time-consuming, expensive, unsafe, and produce environmentally hazardous liquid waste in large volume. This study reveals an alternative method to rinse graphite-oxide using a Soxhlet extractor. Since only the vapor of the solvent is used for washing, Soxhlet rinsing offers reuse of the same solvent for many automatic subsequent cycles, leading to considerable solvent savings, reducing pollutants and work time, and ensuring safer production. The quality of the produced GO is evaluated by Raman spectroscopy, X-Ray diffraction (XRD), inductively coupled plasma (ICP), elemental analysis, and electron microscopy. Moreover, we test the electrochemical performances of reduced GO (rGO), the main final product of graphite-oxide. Finally, we discuss the benefits involved in the suggested rinsing method and compare its profitability with traditional methods. Soxhlet rinsing is favored environmentally and economically. Particularly, the automatic operation of many washing sequences saves labor time, and the reuse of the washing solvent spares a large volume of chemically deleterious solvents.

Surface modifications of carbon nanodots reveal the chemical source of their bright fluorescence.

Fluorescent carbon nanodots (CNDs) have drawn increasing attention in recent years. These cost-effective and eco-friendly nanomaterials with bright fluorescence have been investigated as promising materials for electrooptic and bioimaging applications. However, the chemical source stimulating their strong fluorescence has not been completely identified to date. Depending on the chemical composition, two absorption peaks are observed in the visible range. In this study, we applied selected chemical modifications to CNDs in order to elucidate the correlation between the chemical structure and optical behavior of CNDs. Varying the amount of acetic acid in the synthesis process resulted in different effects on the absorbance and fluorescence photo-spectra. Specifically, at a low concentration (10%), the fluorescence is dramatically red shifted from 340 to 405 nm. Comprehensive characterization of the chemical modification by FTIR and XPS allows identification of the role of acetic acid in the reaction mechanism leading to the modified photoactivity. The functional group responsible for the 405 nm peak was identified as HPPT. We describe a chemical mechanism involving acetic acid that leads to an increased concentration of HPPT groups on the surface of the CNDs. Applying two additional independent chemical and consequently optical modifications namely solution pH and annealing on the nanodots further supports our proposed explanation. Understanding the molecular origin of CND fluorescence may promote the design and control of effective CND fluorescence in optical applications.

Zebrafish lipid droplets regulate embryonic ATP homeostasis to power early development.

In zebrafish embryos, the maternally supplied pool of ATP is insufficient to power even the earliest of developmental events (0-3 hpf) such as oocyte-to-embryo transition (OET). The embryos generate an additional pulse (2.5 h long) of ATP (1.25-4 hpf) to achieve the embryonic ATP homeostasis. We demonstrate that the additional pulse of ATP is needed for successful execution of OET. The maternally supplied yolk lipids play a crucial role in maintaining the embryonic ATP homeostasis. In this paper, we identify the source and trafficking routes of free fatty acids (FFAs) that feed the mitochondria for synthesis of ATP. Interestingly, neither the maternally supplied pool of yolk-FFA nor the yolk-FACoA (fatty acyl coenzyme A) is used for ATP homeostasis during 0-5 hpf in zebrafish embryos. With the help of lipidomics, we explore the link between lipid droplet (LD)-mediated lipolysis and ATP homeostasis in zebrafish embryos. Until 5 hpf, the embryonic LDs undergo extensive lipolysis that generates FFAs. We demonstrate that these newly synthesized FFAs from LDs are involved in the maintenance of embryonic ATP homeostasis, rather than the FFAs/FACoA present in the yolk. Thus, the LDs are vital embryonic organelles that maintain the ATP homeostasis during early developmental stages (0-5 hpf) in zebrafish embryos. Our study highlights the important roles carried on by the LDs during the early development of the zebrafish embryos.

Development and formulation of azospirillum lipoferum and pseudomonas fluorescens as effective biological agents for enhanced agro-productivity / Desenvolvimento e formulação de azospirillum lipoferum e pseudomonas fluorescens enquanto agentes biológicos eficazes para uma agro-produtividade melhorada

Biofertilizer is a group of beneficial microorganisms used for improving the productivity of soil by fixing atmospheric nitrogen or by solubilizing soil phosphorus. They also stimulate plant growth through synthesis of growth promoting substances. In this present study, Azospirillum lipoferum is grown in Nitrogen free Bromothymol blue (Nfb) medium and Pseudomonas fluorescens in King's B medium. Bioprocess condition was optimized for both of the culture and found that Pseudomonas fluorescens has shown highest growth at 300C in pH 8 after 72 hours of incubation where as Azospirillum lipoferum showed highest cell concentration at 310C in pH 7, with incubation period of 72 hours. The optimized culture is mixed with different formulations of powder and liquid carrier such as Saw dust, Rice husk, Date seed powder, Matka khad, Jiwamrit and Beejamrit respectively. Shelf life study for 0, 30, 60, 90 and 120 days by cell counting and spread plate method showed that shelf life of the biofertilizer produced from Powder and liquid carriers had high amount of viable microbial population up to 120 days storage. Among biofertilizer based bio inoculants, Saw dust showed maximum population of 77x109cfu/ml for Azospirillum lipoferum and 72 x 109 CFU/ml for Pseudomonas strain on 120th day and the liquid carrier Matka khad showed 85x109 cfu/ml for Azospirillum lipoferum and 78 x 109 CFU/ml for Pseudomonas fluorescens.

Biofertilizante é um grupo de microorganismos benéficos utilizados para melhorar a produtividade do solo através da fixação de azoto atmosférico ou por solubilização de fósforo no solo. Eles também estimulam o crescimento vegetal através de síntese de substâncias promotoras do crescimento. No presente estudo, Azospirillum lipoferum é cultivado em um meio de azul de bromotimol sem nitrogênio (Nfb) e Pseudomonas fluorescens num meio de King's B. A condição de bioprocesso foi optimizada para ambas as culturas e descobriram que Pseudomonas fluorescens mostraram maior crescimento a 300ºC em pH 8 após 72 horas de incubação, enquanto que Azospirillum lipoferum mostraram maior concentração de células a 310ºC em pH 7, com um período de incubação de 72 horas. A cultura optimizada é misturada com diferentes formulações de pó e veículo líquido tal como serragem, casca de arroz, pó de semente de tâmaras, Matka khad, Jiwamrit e Beejamrit respectivamente. O estudo do prazo de validade para 0, 30, 60, 90 e 120 dias por contagem celular e método de espalhamento em placa mostrou que o prazo de validade do biofertilizante produzido a partir do pó e veículos líquidos teve grande quantidade de população microbiana viável até 120 dias de armazenamento. Entre inoculantes biológicos de base biofertilizantes, a serragem mostrou população máxima de 77x109 CFU/ml para Azospirillum lipoferum e 72 x 109 CFU/ml para a estirpe Pseudomonas no 120º dia e um veículo líquido Matka khad mostrou 85x109 CFU/ml para Azospirillum lipoferum e 78x109 CFU/ml para Pseudomonas fluorescens.

Turnover of the actomyosin complex in zebrafish embryos directs geometric remodelling and the recruitment of lipid droplets.

Lipid droplets (LDs), reservoirs of cholesterols and fats, are organelles that hydrolyse lipids in the cell. In zebrafish embryos, the actomyosin complex and filamentous microtubules control the periodic regulation of the LD geometry. Contrary to the existing hypothesis that LD transport involves the kinesin-microtubule system, we find that their recruitment to the blastodisc depends on the actomyosin turnover and is independent of the microtubules. For the first time we report the existence of two distinct states of LDs, an inactive and an active state, that occur periodically, coupled weakly to the cleavage cycles. LDs are bigger, more circular and more stable in the inactive state in which the geometry of the LDs is maintained by actomyosin as well as microtubules. The active state has smaller and irregularly shaped LDs that show shape fluctuations that are linked to actin depolymerization. Because most functions of LDs employ surface interactions, our findings on the LD geometry and its regulation bring new insights to the mechanisms associated with specific functions of LDs, such as their storage capacity for fats or proteins, lipolysis etc.