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The production of spin-polarized currents in pristine carbon nanotubes with Rashba spin-orbit interactions has been shown to be very sensitive to the symmetry of the tubes and the geometry of the setup. Here we analyze the role of defects on the spin quantum conductances of metallic carbon nanotubes due to an external electric field. We show that localized defects, such as adsorbed hydrogen atoms or pentagon-heptagon pairs, increase the Rashba spin-polarized current. Moreover, this enhancement takes place for energies closer to the Fermi energy as compared to the response of pristine tubes. Such increments can be even larger when several equally spaced defects are introduced into the system. We explore different arrangements of defects, showing that for certain geometries there are flips of the spin-polarized current and even transport suppression. Our results indicate that spin valve devices at the nanoscale may be achieved via defect engineering in carbon nanotubes., A.L. acknowledges the financial support of FAPERJ through Grants No. E-26/102.272/2013 and No. E-26/202.953/2016, CNPq, and INCT em Nanomateriais de Carbono. L.C. acknowledges support from Spanish MINECO through Grant No. FIS2015-64654-P, and helpful conversations with Jorge I. Cerdá. H.S. is grateful for financial support from the Brazilian CAPES.

This article belongs to the Special Issue Lipases and Lipases Modification., The oleaginous yeast Moniliella spathulata R25L270 was the first yeast able to grow and produce extracellular lipase using Macaúba (Acrocomia aculeate) cake as substrate. The novel lipase was recently identified, and presented promising features for biotechnological applications. The M. spathulata R25L270 lipase efficiently hydrolyzed vegetable and animal oils, and showed selectivity for generating cis-5,8,11,15,17-eicosapentaenoic acid from sardine oil. The enzyme can act in a wide range of temperatures (25–48 °C) and pH (6.5–8.4). The present study deals with the immobilization of M. spathulata R25L270 lipase on hydrophobic, covalent and ionic supports to select the most active biocatalyst capable to obtain omega-3 fatty acids (PUFA) from sardine oil. Nine immobilized agarose derivatives were prepared and biochemically characterized for thermostability, pH stability and catalytic properties (KM and Vmax). Ionic supports improved the enzyme–substrate affinity; however, it was not an effective strategy to increase the M. spathulata R25L270 lipase stability against pH and temperature. Covalent support resulted in a biocatalyst with decreased activity, but high thermostability. The enzyme was most stabilized when immobilized on hydrophobic supports, especially Octyl-Sepharose. Compared with the free enzyme, the half-life of the Octyl-Sepharose derivative at 60 °C increased 10-fold, and lipase stability under acidic conditions was achieved. The Octyl-Sepharose derivative was selected to obtain omega-3 fatty acids from sardine oil, and the maximal enzyme selectivity was achieved at pH 5.0., This research was supported by Brazilian agencies: Instituto Nanocell, CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico), INCT (Instituto Nacional de Ciência e Tecnologia) de Nanomateriais de Carbono, FAPEMIG (Fundação de Amparo à Pesquisa do Estado de Minas Gerais), Rede Mineira de Toxinas com Ação Terapêutica, Pro-Reitoria de Pesquisa da UFMG and CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior- Processo: BEX 2703/14-9).

[Background]: Biodiesel industry wastes were evaluated as supplements for lipase production by Moniliella spathulata R25L270, which is newly identified yeast with great lipolytic potential. Macaúba cake (MC), used for the first time in this work as inducer to produce lipases, and residual oil (RO) were mixed to maximise enzyme production. The lipase secreted was biochemically characterised., [Results]: The best ratio for the mixture (MC:RO) was 0.66:0.34 and the fitted values for lipase activity and total protein concentration were 0.98 U mL−1 and 0.356 mg mL−1, respectively. Maximum activity obtained (2.47 U mL−1) was achieved at 31.5°C and pH 6.7, and the enzyme was stable in this condition. A novel enzyme was purified and identified for the first time by mass spectrometry. The lipase efficiently hydrolysed different natural oils and exhibited selectivity in the production of eicosapentaenoic acid from fish oil., [Conclusion]: The use of MC and RO as a supplement to produce the new lipase from M. spathulata R25L270 may be one alternative for reducing lipase production costs and simultaneously adding value to biodiesel industry residues. The potential application of the lipase in the oleochemical industry was demonstrated by its pH and temperature stabilities and selective hydrolysis., This research was supported by Brazilian agencies: CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico), INCT (Instituto Nacional de Ciência e Tecnologia) de Nanomateriais de Carbono, FAPEMIG (Fundação de Amparo à Pesquisa do Estado de Minas Gerais), Rede Mineira de Toxinas com Ação Terapêutica and CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior).

PACS number(s): 71.30.+h, 72.80.Vp, 73.22.Pr.-- et al., The study of two-dimensional (2D) electronic systems is of great fundamental significance in physics. Atomic layers containing hybridized domains of graphene and hexagonal boron nitride (h-BNC) constitute a new kind of disordered 2D electronic system. Magnetoelectric transport measurements performed at low temperature in vapor phase synthesized h-BNC atomic layers show a clear and anomalous transition from an insulating to a metallic behavior upon cooling. The observed insulator to metal transition can be modulated by electron and hole doping and by the application of an external magnetic field. These results supported by ab initio calculations suggest that this transition in h-BNC has distinctly different characteristics when compared to other 2D electron systems and is the result of the coexistence between two distinct mechanisms, namely, percolation through metallic graphene networks and hopping conduction between edge states on randomly distributed insulating h-BN domains. © 2012 American Physical Society., P.M.A. acknowledges support from the Office of Naval Research (ONR) through MURI program, the Basic Energy Sciences division of the Department of Energy (DOE) and Rice University startup funds. L.S. is supported by DOE-BES program DE-SC0001479 for device fabrication and measurement. L.B. is supported by DOE-BES through award DE-SC0002613 and by the NHMFL-UCGP program for measurement. The NHMFL is supported by NSF through NSF-DMR-0084173 and the State of Florida. D.J.M., S.K., and A.R. acknowledge financial support from the Spanish “Juan de la Cierva” program (JCI-2010-08156), Spanish MICINN (FIS2010-21282- C02-01 and PIB2010US-00652), ACI-Promociona (ACI2009-1036), “Grupos Consolidados UPV/EHU del Gobierno Vasco” (IT-319-07), the European Union through the FP7 e-I3 ETSF (Contract No. 211956), European Research Council Advanced Grant DYNamo (ERC-2010-AdG -Proposal No. 267374), and THEMA (Contract No. 228539) projects and the Ikerbasque Foundation. R.B.C. acknowledges financial support from Brazilian agencies CNPq, CAPES, FAPERJ, and INCT—Nanomateriais de Carbono and the ONR MURI program. S.G.L. acknowledges supported from National Science Foundation Grant No. DMR10-1006184 and the ONR MURI program. L.C. is supported by ONR MURI program (Award No. N00014-09-1066) for sample growth. K.S. acknowledges support from the National Science Foundation Major Research Instrumentation program (NSF-MRI) DMR-0619801 and the Department of Energy National Nuclear Security Administration (DOE-NNSA) DE-FG52-05NA27036 and the PVAMU Title III program US department of Education.