Electrochemical exfoliation of graphite for producing graphene using saccharin

A green electrochemical exfoliation route to produce graphene from graphite electrode has been provided. Saccharin which is a non-toxic and biocompatible artificial sweetener was used as an intercalating agent in aqueous media. Graphene samples were produced using five different exfoliation potentials. Microscopic and spectroscopic analysis confirmed the presence of few layer graphene sheets in as-exfoliated product. Important observations made were: (a) graphene layers from nano-to-micro meter sizes were produced; (b) number of graphene layers decreased with increase in the intercalation potential, (c) yield of graphene increased with increase in the exfoliation potential and (d) defect density in the exfoliated graphene layer was sensitive to the exfoliation potential in a way that with increase in the exfoliation potential the defect density initially increased and then eventually decreased.

Photoinduced DNA Crosslink Formation by Dichloridooxidovanadium(IV) Complexes of Polypyridyl Bases

Oxidovanadium(IV) complexes VO(pyphen)Cl-2] (1) and VO(pydppz)Cl-2] (2), where pyphen is 2-(2-pyridyl)-1,10-phenanthroline and pydppz is 3-(pyridin-2-yl)dipyrido3,2-a:2,3-c]phenazine, show remarkable photoinduced DNA crosslinking ability and photocytotoxicity. The complexes are non-electrolytes in DMF, 1:1 electrolytes in 20% aqueous DMF, and 1:2 electrolytes in 20% aqueous DMF upon photoirradiation with visible light of 400-700 nm. The paramagnetic complexes, which have one unpaired electron, show a d-d band near 780 nm in aqueous DMF. The IR data suggest a V=O moiety trans to a V-N bond. Complex VO(pydppz)Cl-2] (2), as a novel photoinducible nuclear ds-DNA crosslinking agent, shows visible-light-induced cytotoxicity in HeLa and MCF-7 cancer cells by an apoptotic pathway, giving IC50 values of 0.87 +/- 0.07 and 1.4 +/- 0.2 M, respectively, while being essentially nontoxic (IC50 > 40 M) in the dark and less toxic in normal MCF-10A cells.

Visible light-induced cytotoxicity of a dinuclear iron(III) complex of curcumin with low-micromolar IC50 value in cancer cells

Photoactive metal complexes have emerged as potential candidates in the photodynamic therapy (PDT) of cancer. We present here the synthesis, characterization and visible light-triggered anticancer activity of two novel mixed-ligand oxo-bridged iron(III) complexes, viz., {Fe(L)(acac)}(2)(mu-O)](ClO4)(2) (1) and {Fe (L)(cur)}(2)(mu-O)](ClO4)(2) (2) where L is bis-(2-pyridylmethyl)-benzylamine, acac is acetylacetonate and cur is the monoanion of curcumin (bis(4-hydroxy-3-methoxyphenyl)-1,6-diene-3,5-dione). The crystal structure of complex 1 (as PF6 salt, 1a) shows distorted octahedral geometry of each iron(III) centre formed by the FeN3O3 core. The 1: 2 electrolytic complexes are stable in solution and retain their oxo-bridged identity in aqueous medium. Complex 2 has a strong absorption band in the visible region and shows promising photocytotoxicity in HeLa and MCF-7 cancer cells in visible light giving respective IC50 values of 3.1 +/- 0.4 lM and 4.9 +/- 0.5 lM while remains non-toxic in the dark (IC50 > 50 lM). The control complex 1 is inactive both in the light and dark. Complex 2 accumulates in cytoplasm of HeLa and MCF-7 cells as evidenced from fluorescence microscopy and triggers apoptotic cell death via light-assisted generation of reactive oxygen species (ROS). Taken together, complex 2 with its promising photocytotoxicity but negligible dark toxicity in cancer cells has significant photochemotherapeutic potential for applications in PDT. (C) 2015 Elsevier B.V. All rights reserved.

Environmental friendly aquaculture key to sustainable fish farming development in Nigeria

Aquaculture production in Nigeria has increased tremendously in recent times; along with this increase is the rise in the level of waste outputs from aquaculture practices. The discharge of waste from aquaculture operations on continuous basis leads to eutrophication and destruction of natural ecosystem in receiving water body. Controlled wastes production strategies is necessary to maintain sustainable aquaculture growth into the future, as long-term sustainability of fish culture systems depends on their ability to reduce their waste outputs. The release of solid wastes is mainly a function of the digestibility of various dietary components while the release of dissolved wastes is mainly a function of the metabolism of nutrients by the fish. This paper critically reviews the impacts of aquaculture wastes on the environment and the strategies to mitigate the effect of these impacts. Future trends and research needs on aquaculture induced effluents are outlined. As the amount of nutrient discharge is typically site and operation specific, effective farm management has been identified as the most important factor to avoid effluent pollution.

Biocompatibilidade do polissacarídeo celulósico sintetizado por zoogloea sp.: um estudo em bexigas de coelho

Atualmente, o material utilizado para o tratamento endoscópico é o Deflux, porém este é um material não-biológico. Sabe-se que a substância ideal deve ser atóxica, biocompatível, não-migratória, não-antigênica e deve causar o mínimo possível de inflamação no local do implante. A bactéria Zoogloea sp. produz um exopolissacarídeo celulósico (CEP) com baixa citotoxicidade e alto biocompatibilidade. O objetivo deste estudo é investigar, na bexiga de coelho, a biocompatibilidade de implantes de exopolissacarídeo de celulose, produzidos pela Zooglea sp. Foram utilizados como modelo experimental, 20 coelhos adultos da raça Califórnia, com média de seis meses de idade. Os animais foram divididos em dois grupos, sendo o grupo G1, composto por animais mortos três dias após a aplicação do implante (n=9), e o grupo G2, composto por animais mortos três meses após a aplicação do implante (n=11). Cada animal recebeu, no total, quatro implantes, sendo dois de gel de biopolímero e dois de gel Deflux. Foram realizadas as técnicas imunohistoquímicas para marcação de colágeno tipos I e III, alfa-actina de músculo liso, PCNA e reação química TUNEL. Nas amostras de três dias, os implantes de CEP e deflux, eram estruturalmente homogêneos e livres de células inflamatórias ou vasos sanguíneos. Por outro lado, nas amostras de três meses, com exceção de algumas áreas, o CEP estava organizado como feixes curtos que eram sugestivos de um tecido fibroso. Apesar disso, o implante de CEP corou negativamente para colágenos tipos I e III, fibras elásticas, enquanto que o tricrômico de masson, não indicou a presença de colágeno. Em contraste as áreas de implante de deflux nas amostras de três meses estavam fragmentadas, mas ainda eram homogêneas, e ainda não havia nenhuma célula nem vaso sanguíneo em seu interior. As células positivas para PCNA podiam ser claramente percebidas dentro dessas ilhotas, dessa forma indicando um processo inflamatórioproliferativo, em curso. No grupo sacrificado aos três meses, os implantes de deflux ainda estavam negativos, mas em torno das áreas de CEP algumas células positivas para a técnica do TUNEL eram perceptíveis. Nos implantes de CEP de três meses, muitos vasos sanguíneos eram visualizados, e a sua densidade era de 23.865.48. A densidade de microvasos na lâmina própria (41.5111.19) foi significativamente diferente (p<0.001) daquela no implante de CEP. Nossos resultados mostraram que o CEP possui pouca imunogenicidade e se integra melhor no tecido hospedeiro quando comparado ao deflux. Portanto o CEP deve ser um material eficiente em casos em que a incorporação ao tecido é desejada como por exemplo em estruturas de suporte na cirurgia de reconstrução

Diet and feeding ecology of two sizes of Barbodes gonionotus (=Puntius gonionotus) and Oreochromis sp. in ricefields in Bangladesh

Fish culture experiments were conducted to compare and evaluate the feeding pattern and strategies, daily ration, gastric evacuation rates, dietary breadth, similarity and overlap of silver barb, Barbodes gonionotus, and tilapia, Oreochromis sp. (natural hybrid of O. mossambicus x O. niloticus) in a rice-fish system. B. gonionotus was found to be a macrophtophagous column feeder while Oreochromis sp. was a detrivorous benthophagic browser. Ontogenic shifts in diet were clearly observed in B. gonionotus while absent in Oreochromis sp. For both species, daily food ration for the small fish was twice as large as that for the large fish. Mean rates of gastric evacuation were 0.18 h super(1) for small and 0.05 h super(1) for large B. gonionotus and 0.09 h super(1) and 0.14h super(1) for small and large Oreochromis sp., respectively. In terms of intraspecific dietary width, the smaller sized individuals of both species had a wider dietary niche than the larger conspecifics. Larger fish increased their specialization and reliance on few food items with increasing size and competitive ability. When both species were reared together, B. gonionotus showed a wider niche width than tilapia. Wider interspecific niche width of B. gonionotus compared to that of tilapia and significant interspecific dietary overlap is likely to result in suppression of the growth of tilapia in mixed culture due to: 1) a high degree of specialization and reliance of tilapia on food of low-nutrient value, and 2) slower gastric evacuation rates as compared to B. gonionotus, which would allow B. gonionotus to outgrow similar sized tilapia.

Matrilineal Components and Genetic Relationship of Silkies from China and Japan

Silkie is a famous black-bone chicken breed with beautiful silky feather. The unique medical property of this chicken was recorded in Chinese traditional medicine dictionary about 700 years ago. In this study, we analyzed the mtDNA D-loop sequence variation of 26 Bairong Silkies from Fujian Province, China, together with 100 reported Silkie mtDNAs from China and Japan, and studied their matrilineal components and genetic relationship. A total of 21 haplotypes were detected, which could be assigned to six haplogroups (A-E, G). Among them, haplogroups D and G were exclusively presented in Japanese Silkies and Chinese Silkies, respectively. Chinese Silkies had higher frequency of lineages belonging to haplogroups A, B, and E, and lower frequency of haplogroup C than Japanese Silkies. For the four Chinese Silkie populations, most of samples of Taihe, Chengdu, and Hubei Silkies were grouped in haplogroups A, B, and C, whereas most of Bairong Silkies were grouped in haplogroup E. Five haplotypes were shared by Japanese and Chinese Silkies. The genetic diversity of each Silkie population varied, but the overall diversity of Chinese Silkies was similar to that of Japanese Silkies. Taken together, our results confirmed the genetic connection between Chinese and Japanese Silkies, but also clearly showed that the matrilineal genetic structures of Chinese and Japanese Silkies had some differences.

Polymer waveguide-based backplanes for board-level optical interconnects

Optical interconnects are increasingly considered for use in high-performance electronic systems. Multimode polymer waveguides are a promising technology for the formation of optical backplane as they enable cost-effective integration of optical links onto standard printed circuit boards. In this paper, two different types of polymer waveguide-based optical backplanes are presented. The first one implements a passive shuffle architecture enabling non-blocking on-board optical interconnection between different cards/modules, while the second one deploys a regenerative bus architecture allowing the interconnection of an arbitrary number of electrical cards over a common optical bus. The polymer materials and the multimode waveguide components used to form the optical backplanes are presented, while details of the interconnection architectures and design of the backplanes are described. Proof-of-principle demonstrators fabricated onto low-cost FR4 substrates, including a 10-card 1 Tb/s-capacity passive shuffle router and 4-channel 3-card polymeric bus modules, are reported and their optical performance characteristics are presented. Low-loss, low-crosstalk on-board interconnection is achieved and error-free (BER10 12) 10 Gb/s communication between different card/module interfaces is demonstrated in both polymeric backplane systems. © 2012 IEEE.

Allelopathic interactions between the Potamogeton spp and toxic cyanobacteria (Microcystis aeruginosa)

This study aimed to investigate the allelopathic activities between 3 Potamogeton spp. (Potamogeton maackianus, Potamogeton malaianus and Potamogeton pectinatus) and the toxic cyanobacteria (Microcystis aeruginosa). All Potamogeton spp inhibited the growth of M. aeruginosa in both coexistence and exudates experiments. Inhibition of M. aeruginosa growth by plant exudates depended strongly on the biomass of P malaianus. Initial pH (6.5-9.8) did not influence the inhibitory effects of P. malaianus exudates. However, the M. aeruginosa inhibited the net photosynthesis and respiration of all three pondweed test spp.. The decreases in photosynthesis and respiration were probably caused by the toxic compounds released by M. aeruginosa, rather than its shading effects. The M. aeruginosa also decreased the nutrients (phosphorus and nitrogen) uptake rates of macrophytes. The absorption rates of phosphorus and nitrogen and net photosynthesis were decreased sharply. These results will help to restore submerged plants in eutrophic waters.

Allelopathic effects of phenolic compounds present in submerged macrophytes on Microcystis aeruginosa

In laboratory studies, the allelopathic effects of 3 (Hydrocharitaceae family) submerged macrophytes (Elodea nuttallii (Planch) St. John, Hydrilla verticillata (L.f.) Royle and Vallisneria spiralis L.) were investigated on two strains of Microcystis aeruginosa. Both aqueous methanol extracts and exudates of three macrophytes inhibited the growth of both strains of Microcystis aeruginosa, After 3-days culture, E nuttallii, H. verticillata and V. spiralis excreted 0.8, 0.3 and 1.0% of total phenolic compounds (TPC), respectively, into the surrounding water. After removing phenolic compounds by polyvinylpolypyrrolidone (PVPP)), the plant exudates showed very weak activity. The inhibitory rates of exudates of E. nuttallii, H. verticillata and V. spiralis, against non-toxic M. aeruginosa were decreased by 35.7, 43.4 and 59.1% respectively. Thus 3 submerged macrophytes released the phenolic compounds into the surrounding water, to inhibit the growth of M. aeruginosa. This information may help us in understanding the mechanism of allelopathy in aquatic ecosystems and to control the algal bloom in eutrophic water bodies.

Experimental studies on the effects of toxic Microcystis aeruginosa PCC7820 on the survival and reproduction of two freshwater rotifers Brachionus calyciflorus and Brachionus rubens

Blooms of Microcystis aeruginosa frequently occur in many eutrophic lakes in China, however, there is very little experimental study on the relationship between Microcystis and rotifers from Chinese waters. The effects of different concentrations of toxic M. aeruginosa PCC7820 on two common freshwater rotifers Brachionus calyciflorus and B. rubens were investigated in laboratory experiments. B. calyciflorus was able to utilize this strain of M. aeruginosa as a food source. However, M. aeruginosa suppressed the survival and reproduction of B. calyciflorus at the highest concentration (10(6) cells/ml) probably due to the inadequate nutrition. B. rubens was inhibited by toxic M. aeruginosa PCC7820 and the inhibition increased with the increasing Microcystis concentration. Our study indicates that the two rotifers have different sensitivities to toxic M. aeruginosa and that toxic cyanobacteria may affect zooplankton community structure by differentially inhibiting the different zooplankton taxa.

The role of NH4+ toxicity in the decline of the submersed macrophyte Vallisneria natans in lakes of the Yangtze River basin, China

Experimental and field studies were conducted to evaluate the effects of NH4+ enrichment on growth and distribution of the submersed macrophyte, Vallisneria natans L, in lakes of the Yangtze River in China, based on the balance between free amino acids (FAA) and soluble carbohydrates (SC) in the plant tissue. Increase of NH4+ rather than NO3- concentrations in the water column caused FAA accumulation and SC depletion of the plant. The plant showed a unimodal pattern of biomass distribution along both FAA/SC ratios and external NH4+ concentrations, indicating that a moderate NH4-N concentration (< 0.3 mg L-1) benefited the plant, whereas the high NH4-N concentration (> 0.56 mg L-1) eliminated the plant completely. Therefore, 0.56 mg NH4-N mg L-1 in the water column was taken as the upper limit for V. natans in lakes of the Yangtze River basin. The mesocosm experiment showed that at a high external NH4-N (0.81 mg L-1), V. natans failed to propagate with a loss of half SC content (5 mg g(-1) DW) in the rhizomes, indicating that the consumption of carbohydrates for detoxification of excess NH4+ into non-toxic FAA significantly diminished carbohydrate supply to the rhizomes. This might consequently inhibit the vegetative reproduction of the plant, and also might be an important cause for the decline and disappearance of the plant with eutrophication. The present study for the first time reports substantial ecophysiological evidences for NH4+ stress to submersed macrophytes, and indicates that NH4+ toxicity arising from eutrophication probably plays a key role in the deterioration of submersed macrophytes like V. natans.

Monitoring bioaccumulation and toxic effects of hexachlorobenzene using the polyurethane foam unit method in the microbial communities of the Fuhe River, Wuhan

Hexachlorobenzene (HCB) is a chlorinated aromatic hydrocarbon that was widely used for seed dressing in prevention of fungal growth on crops, and also as a component of fireworks, ammunition, and synthetic rubbers. Because of its resistance to degradation and mobility, HCB is widely distributed throughout the environment and is accumulated through food chains in different ecosystems. In this study, a preliminary investigation was carried out on the bioaccumulation and the toxic effects of HCB in the microbial (protozoan in particular) communities in the Fuhe River, Wuhan, a water body receiving industrial wastewaters containing HCB and other pollutants, using the standardized polyurethane foam units (PFU) method. Field samples were taken from eight stations established along the Fuhe River in January and August 2006. The concentration ratios of HCB in microbial communities and in water were 9.66-18.64, and the microbial communities accumulated 13.29-56.88 mu g/L of HCB in January and 0.82-10.25 mu g/L HCB in August. Correlation analysis showed a negative correlation between the HCB contents in the microbial assemblage, and the number of species and the diversity index of the protozoan communities. This study demonstrated the applicability of the PFU method in monitoring the effects of HCB on the level of microbial communities.

氮杂环化合物的绿色合成研究

氮杂环化合物大多数都是具有生理活性的物质，例如喹喔啉化合物与苯二氮卓类化合物，因此研究氮杂环化合物骨架的构建方法具有一定意义。绿色化学的迅速发展迫切要求化学家发展清洁、经济和环境较友好条件下的有机合成方法。其中，水相反应与绿色固体酸催化剂的使用都是实现绿色有机合成的重要途径，它们非常具有潜力，近些年受到了广泛关注。本论文的主要工作是围绕水相及固体酸催化条件下两类具有生物活性的含氮杂环小分子的合成方法而开展的，具体包括以下内容： 1. 研究和探索出了两类绿色固体酸催化剂蒙脱土（Mont. K-10）和杂多酸(H4SiW12O40), 在水相条件下成功合成出喹喔啉化合物的有效方法。两个催化体系都以无毒无公害的水作反应溶剂，实验条件温和，操作安全简便，反应速度快，底物普适性强，产率高，且产物易分离收集。两类固体酸催化剂，对设备腐蚀性小，可回收循环使用，对环境无公害; 蒙脱土催化大部分底物能得到当量产率的产物，硅钨酸催化催化剂负载量小。 2. 实现了无溶剂条件下，以杂多酸（H3PW12O40）作催化剂，高效合成1,5-苯二氮卓衍生物的合成方法。该催化体系具有以下一些优势：实验条件温和，反应速度较快，底物普适性良好，产物易分离收集，反应过程中没有加入其它有机溶剂，绿色环保。 ‘Green Chemistry’ is currently a major issue of modern chemistry. It is widely acknowledged that there is a growing need for more environmentally acceptable processes in the chemical industry. New green catalysts and green reaction media are the important and efficient strategies in green chemistry. New green catalysts include solid acid catalysts, solid base catalysts, metal catalysts not only possess higher activity and selectivity, but also are easily separated from reaction system. Green reaction media include water, supercritical fluids and ionic liquids can not only substitute traditional toxic and harmed organic solvents, but also improve reaction activity and selectivity. Meanwhile water is a promising green reaction medium for use in modern chemistry because it has a number of advantages such as the cheapest solvent available on earth, being non-hazardous and non-toxic to the environment. Solid acids had also attracted much attention for realizing green chemistry due to their unique acidity, high activity and efficiency as organic catalysts. Nitrogen-containing heterocyclic compounds of different ring sizes such as quinoxaline and benzodiazepine are the important pharmacologically active compounds. Due to the wide biological significance of these compounds, the synthesis of these types of compounds have received a great deal of attention. Despite the large availability of methods to construct nitrogen-containing heterocyclic compounds, there is still a strong need to further explore green methods to efficiently and safely synthesize these compounds. Thus, we aim at developing efficient and green methodology for the synthesis of quinoxaline and benzodiazepine carried out under water condition with solid acid catalysts. The contents of this dissertation are listed as the following: 1. We have developed two catalytic systems for the synthesis quinoxaline via the condensation of an aryl 1,2-diamine with a 1,2-diketone compound in the presence of Mont. K-10 or H4SiW12O40 as a catalyst in water solvent. Both of these two methods can be applied to wide range of substrates, tolerating aryl 1,2-diamine/1,2-diketone with the electron donating/drawing substituent. Operational simplicity, the ambient conditions, use of an economically convenient catalyst, use of water as a desirable solvent, high yields and short reaction times are the key features of these two protocols. 2. We developed a convenient and efficient protocol for the synthesis of a variety of 1,5-benzodiazepines in high yields via condensation of aryl o-phenylenediamine derivatives with a variety of ketones using H3PW12O40 as a green recyclable and heterogeneous catalyst under solvent-free condition. The simple experiment procedure combined with ease of recovery and reuse of this catalyst make this procedure quite simple, more convenient and environmentally benign.

Role of five-quark components in radiative and strong decays of the Lambda(1405) resonance

Within an extended chiral constituent quark model, the three- and five-quark structure of the S-01 resonance Lambda(1405) is investigated. Helicity amplitudes for electromagnetic decays [Lambda(1405)->Lambda(1116)gamma, Sigma(1194)gamma] and transition amplitudes for strong decays [Lambda(1405)->Sigma(1194)pi, K- p] are derived, as well as the relevant decay widths. The experimental value for the strong decay width, Gamma(Lambda(1405)->(Sigma pi)degrees) = 50 +/- 2MeV, is well reproduced with about 50% of a five-quark admixture in the Lambda(1405). Important effects owing to the configuration mixing among Lambda P-2(1)A, Lambda P-2(8)M, and Lambda P-4(8)M are found. In addition, transitions between the three- and the five-quark components in the baryons turn out to be significant in both radiative and strong decays of the Lambda(1405) resonance.