Mercury clathration-driven phase transition in a luminescent bipyrazolate metal-organic framework: a multitechnique investigation

Mercury is one of the most toxic heavy metals. By virtue of its triple bond, the novel ligand 1,2-bis(1H-pyrazol-4-yl)ethyne (H2BPE) was expressly designed and synthesized to devise metal-organic frameworks (MOFs) exhibiting high chemical affinity for mercury. Two MOFs, Zn(BPE) and Zn(BPE)·nDMF [interpenetrated i-Zn and noninterpenetrated ni-Zn·S, respectively; DMF = dimethylformamide], were isolated as microcrystalline powders. While i-Zn is stable in water for at least 15 days, its suspension in HgCl2 aqueous solutions prompts its conversion into HgCl2@ni-Zn. A multitechnique approach allowed us to shed light onto the observed HgCl2-triggered i-Zn-to-HgCl2@ni-Zn transformation at the molecular level. Density functional theory calculations on model systems suggested that HgCl2 interacts via the mercury atom with the carbon-carbon triple bond exclusively in ni-Zn. Powder X-ray diffraction enabled us to quantify the extent of the i-Zn-to-HgCl2@ni-Zn transition in 100-5000 ppm HgCl2 (aq) solutions, while X-ray fluorescence and inductively coupled plasma-mass spectrometry allowed us to demonstrate that HgCl2 is quantitatively sequestered from the aqueous phase. Irradiating at 365 nm, an intense fluorescence is observed at 470 nm for ni-Zn·S, which is partially quenched for i-Zn. This spectral benchmark was exploited to monitor in real time the i-Zn-to-HgCl2@ni-Zn conversion kinetics at different HgCl2 (aq) concentrations. A sizeable fluorescence increase was observed, within a 1 h time lapse, even at a concentration of 5 ppb. Overall, this comprehensive investigation unraveled an intriguing molecular mechanism, featuring the disaggregation of a water-stable MOF in the presence of HgCl2 and the self-assembly of a different crystalline phase around the pollutant, which is sequestered and simultaneously quantified by means of a luminescence change. Such a case study might open the way to new-conception strategies to achieve real-time sensing of mercury-containing pollutants in wastewaters and, eventually, pursue their straightforward and cost-effective purification

Chemical Composition, Antioxidant, Antimicrobial and Antidiabetic Potential of Philodendron Bipinnatifidum Schott ex Endl

Many of the species used in popular medicine do not have their biological activities already proven by scientific studies. Among these species, the endemic South American Philodendron bipinnatifidum Schott ex Endl deserves special attention since it is already in use in popular medicine for inflammation cases, such as erysipelas, orchitis and ulcers. This study evaluated the antioxidant, antimicrobial and antidiabetic activities of extracts of the hastes de P. bipinnatifidum. The ethanolic extract showed a significant antioxidant potential. The ethyl acetate extract resulted in high antimicrobial activity against Streptococcus pyogenes. The most significant biological activity of ethyl acetate extract relates to its chemical composition when compared with ethanolic extract, which showed the highest concentration of bioactive compounds. In vitro antidiabetic activity was only evaluated for ethyl acetate extract, resulting in inhibition of intestinal disaccharidases (maltase and sucrase) at concentration of 500 μg/mL

Compositional analysis and physicochemical and mechanical testing of tanned rabbit skins

[EN] Chemical composition and physicochemical and mechanical parameters of New Zealand White rabbit tanned skin were evaluated. Skin samples from 70-d-old males, in natura and semi-finished, were collected for evaluation. The in natura treatment comprise skins without any processing, while semi-finished treatment comprise skins after soaking, fleshing, liming, de-liming, purging, degreasing, pickling, tanning, neutralising, re-tanning and dyeing, followed by oiling, drying, stretching and softening. After tanning, samples from the dorsal and flank regions were removed for tensile and physicochemical testing in the longitudinal and transverse directions. A split plot design was used with plot treatments (leather regions: R1=dorsal and R2=flank) and subplots directions (S1=longitudinal and S2=transversal), using 10 examples per treatment. At the end of processing, the leather analysis revealed low moisture (31.76%), protein (46.48%) and fat content (24.95%), and a high ash content (8.58%). Leather presented a pH of 4.9 and contained 2.0% chromium oxide, 25.5% extractable substances in dichloromethane, and these characteristics were coupled with a higher tensile strength (10.84 N/mm2) in the dorsal region. However, samples in the same region proved to have higher elasticity (64.57%) in the longitudinal direction, although there was no difference in the progressive tearing analysis (21.07-23.50 N/mm). Overall, our analyses suggest that, in this case, the tanned leather product does not have sufficient resistance for application in clothing production.Souza, MR.; Hoch, AL.; Gasparino, E.; Scapinello, C.; Mesquita Dourado, D.; Claudino Da Silva, SC.; Lala, B. (2016). Compositional analysis and physicochemical and mechanical testing of tanned rabbit skins. World Rabbit Science. 24(3):233-238. doi:10.4995/wrs.2016.4037SWORD233238243ABNT. Associação Brasileira de Normas Técnicas. 2014. ABNT NBR ISO 3376: 2014 - Couro - Ensaios físicos e mecânicos – Determinação de resistência à tração e alongamento percentual. Rio de Janeiro, 1-5.ABNT. Associação Brasileira de Normas Técnicas. 2014. NBR - 2589: Couro - Ensaios físicos e mecânicos - Determinação da espessura. Rio de Janeiro, 1.ABNT. Associação Brasileira de Normas Técnicas. 2013. NBR - 11030: couro - Determinação de substâncias extraíveis com diclorometano (CH2Cl2). Rio de Janeiro, 1-3.ABNT. Associação Brasileira de Normas Técnicas. 2013. ABNT NBR 11032: 2013 - Pele e couro - Amostragem na amostra de teste - Procedimento. Rio de Janeiro, 1-4.ABNT. ABNT Associação Brasileira de Normas Técnicas. 2014. NBR – 5398-1: Couro – determinação química do teor de óxido de cromo Parte 1: Quantificação por titulação. Rio de Janeiro, 1-5.ABNT. Associação Brasileira de Normas Técnicas. 2014. NBR - 3377-2: Couro – Ensaios físicos e mecânicos — Determinação da força de rasgamento Parte 2: Rasgamento de extremidade dupla. Rio de Janeiro, 1-3.ABNT. Associação Brasileira de Normas Técnicas. 2014. ABNT NBR 10455: 2014 - Clima de materiais utilizados em calçados e artigos relacionados fabricar. Rio de Janeiro, 1-2.ABNT. Associação Brasileira de Normas Técnicas. 2006. NBR – 11057: Couro –determinação do pH e da cifra diferencial. 2. ed. Rio de Janeiro, 1-3.Cunniff P.A. 1998. Official Methods of Analysis of AOAC International. 16th ed. Arlington: Association of Official Analytical Chemists.Franco, M.L.R.S. 2007. Curtimento de pele de tilápia. In: Boscolo, W.r., Feiden, A. (Orgs.) Industrialização de tilápias. Toledo: GFM Gráfica e editora, 185-223.Freire M.C., Canl R.M. 2000. A pele bovina como matéria-prima. Revista Nacional da Carne, 24: 100-110.Gerhard J. 1998. Posibles fallas e el cuero y e su producción – conceptos, causas, consecuencias, remedios y tipos de cueros. Partner Rübelmann GmbH: Lampertheim (Alemania).Gutterres M. 2001. Distribuição, deposição e interação química de substâncias de engraxe no couro. In: Congresso da federação latino-americana das associações dos químicos e técnicos da indústria do couro, 15, Salvador. Anais... v.1, 108-119.Gutterres M. 2003. Efeito do Curtimento sobre a Microestrutura Dérmica. Revista do Couro Abqtic, Estância Velha, 26: 56-59.Oliveira A.C., Souza M.L.R., Hoch A.L.V., Gasparino E., Scapinello C., Kffuri V.R. Domingues M.C. 2007. Resistência dos couros de coelhos em função do sexo e da idade de abate. Tecnicouro, 28: 52-56.Prado M., Franco M.L.R.S., Uchimura C.M., Souza E.D., Bordignon A.C., Justen A.P., Silva S.C.C., Del Vesco A.P. 2013. Efeito da etapa de engraxe no processo de curtimento das peles de coelhos. Acta Tecnológica, 8: 8-11. http://portaldeperiodicos.ifma.edu.br/index.php/actatecnologica/article/view/131SAEG. 2000. Sistemas de Análises Estatísticas e Genéticas. Versão 8.0. Universidade Federal de Viçosa. Viçosa.Souza M.L.R. 2004. Tecnologia para processamento das peles de peixe. Maringá, PR. Coleção Fundamentum, 11: 14-55.Souza M.L.R. 2006. Tecnologia para processamento de peles de coelhos: peleteria e couro. In Proc: 3rd Rabbit Congress of the Americas, 2006, Maringá –Pr, Brasil. v. 1.Souza M.L.R. 2008. Tecnologia para processamento das peles de peixe. Maringá: Eduem. 3° Ed