Nonreciprocal coherent coupling of nanomagnets by exchange spin waves

Nanomagnets are widely used to store information in non-volatile spintronic devices. Spin waves can transfer information with low-power consumption as their propagations are independent of charge transport. However, to dynamically couple two distant nanomagnets via spin waves remains a major challenge for magnonics. Here we experimentally demonstrate coherent coupling of two distant Co nanowires by fast propagating spin waves in an yttrium iron garnet thin film with sub-50 nm wavelengths. Magnons in two nanomagnets are unidirectionally phase-locked with phase shifts controlled by magnon spin torque and spin-wave propagation. The coupled system is finally formulated by an analytical theory in terms of an effective non-Hermitian Hamiltonian. Our results are attractive for analog neuromorphic computing that requires unidirectional information transmission. [Figure not available: see fulltext.]Accepted Author ManuscriptQN/Bauer Grou

Direct microbial electron uptake as a mechanism for stainless steel corrosion in aerobic environments

Shewanella oneidensis MR-1 is an attractive model microbe for elucidating the biofilm-metal interactions that contribute to the billions of dollars in corrosion damage to industrial applications each year. Multiple mechanisms for S. oneidensis-enhanced corrosion have been proposed, but none of these mechanisms have previously been rigorously investigated with methods that rule out alternative routes for electron transfer. We found that S. oneidensis grown under aerobic conditions formed thick biofilms (∼50 µm) on stainless steel coupons, accelerating corrosion over sterile controls. H2 and flavins were ruled out as intermediary electron carriers because stainless steel did not reduce riboflavin and previous studies have demonstrated stainless does not generate H2. Strain ∆mtrCBA, in which the genes for the most abundant porin-cytochrome conduit in S. oneidensis were deleted, corroded stainless steel substantially less than wild-type in aerobic cultures. Wild-type biofilms readily reduced nitrate with stainless steel as the sole electron donor under anaerobic conditions, but strain ∆mtrCBA did not. These results demonstrate that S. oneidensis can directly consume electrons from iron-containing metals and illustrate how direct metal-to-microbe electron transfer can be an important route for corrosion, even in aerobic environments.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Team Arjan Mo

Adaptive bidirectional extracellular electron transfer during accelerated microbiologically influenced corrosion of stainless steel

Microbiologically influenced corrosion of metals is prevalent in both natural and industrial environments, causing enormous structural damage and economic loss. Exactly how microbes influence corrosion remains controversial. Here, we show that the pitting corrosion of stainless steel is accelerated in the presence of Shewanella oneidensis MR-1 biofilm by extracellular electron transfer between the bacterial cells and the steel electrode, mediated by a riboflavin electron shuttle. From pitting measurements, X-ray photoelectron spectroscopy and Mott-Schottky analyses, the addition of an increased amount of riboflavin is found to induce a more defective passive film on the stainless steel. Electrochemical impedance spectroscopy reveals that enhanced bioanodic and biocathodic process can both promote the corrosion of the stainless steel. Using in situ scanning electrochemical microscopy, we observe that extracellular electron transfer between the bacterium and the stainless steel is bidirectional in nature and switchable depending on the passive or active state of the steel surface.Team Arjan Mo

Engineering NADH/NAD⁺ ratio in Halomonas bluephagenesis for enhanced production of polyhydroxyalkanoates (PHA)

Halomonas bluephagenesis has been developed as a platform strain for the next generation industrial biotechnology (NGIB) with advantages of resistances to microbial contamination and high cell density growth (HCD), especially for production of polyhydroxyalkanoates (PHA) including poly(3-hydroxybutyrate) (PHB), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). However, little is known about the mechanism behind PHA accumulation under oxygen limitation. This study for the first time found that H. bluephagenesis utilizes NADH instead of NADPH as a cofactor for PHB production, thus revealing the rare situation of enhanced PHA accumulation under oxygen limitation. To increase NADH/NAD+ ratio for enhanced PHA accumulation under oxygen limitation, an electron transport pathway containing electron transfer flavoprotein subunits α and β encoded by etf operon was blocked to increase NADH supply, leading to 90% PHB accumulation in the cell dry weight (CDW) of H. bluephagenesis compared with 84% by the wild type. Acetic acid, a cost-effective carbon source, was used together with glucose to balance the redox state and reduce inhibition on pyruvate metabolism, resulting in 22% more CDW and 94% PHB accumulation. The cellular redox state changes induced by the addition of acetic acid increased 3HV ratio in its copolymer PHBV from 4% to 8%, 4HB in its copolymer P34HB from 8% to 12%, respectively, by engineered H. bluephagenesis. The strategy of systematically modulation on the redox potential of H. bluephagenesis led to enhanced PHA accumulation and controllable monomer ratios in PHA copolymers under oxygen limitation, reducing energy consumption and scale-up complexity.Accepted Author ManuscriptOLD BT/Cell Systems Engineerin

Levels and potential health hazards of PCBs in shallow groundwater of an e-waste recycling area, China

The improper disassembly of polychlorinated biphenyl (PCB)-containing equipments such as capacitor and electrical transformer can lead to PCB pollution. To investigate the levels and patterns of PCBs in shallow groundwater in regions where PCB-containing equipment is disassembled, 19 shallow groundwater samples were collected from a recycling area for waste capacitors and electrical transformers in southeastern China. The I 21 pound PCBs in shallow groundwater had a large variation ranging from 6.22 to 97.3 ng L-1, with a mean of 31.6 ng L-1 and low chlorinated PCBs (3-5 chlorinated biphenyls) were predominant homologs in majority groundwater samples. The United States Environmental Protection Agency (US EPA) toxic equivalents of 6 shallow groundwater samples with detectable dioxin-like PCBs varied greatly from 0.29 to 650 pg L-1, and all of them posing serious cancer risk (> 1 x 10(-6)) to children and adults. Much attention should be paid to the vertical migration of low chlorinated PCBs and the cancer risk of dioxin-like PCBs in the study area and similar e-waste recycling areas.The improper disassembly of polychlorinated biphenyl (PCB)-containing equipments such as capacitor and electrical transformer can lead to PCB pollution. To investigate the levels and patterns of PCBs in shallow groundwater in regions where PCB-containing equipment is disassembled, 19 shallow groundwater samples were collected from a recycling area for waste capacitors and electrical transformers in southeastern China. The I 21 pound PCBs in shallow groundwater had a large variation ranging from 6.22 to 97.3 ng L-1, with a mean of 31.6 ng L-1 and low chlorinated PCBs (3-5 chlorinated biphenyls) were predominant homologs in majority groundwater samples. The United States Environmental Protection Agency (US EPA) toxic equivalents of 6 shallow groundwater samples with detectable dioxin-like PCBs varied greatly from 0.29 to 650 pg L-1, and all of them posing serious cancer risk (> 1 x 10(-6)) to children and adults. Much attention should be paid to the vertical migration of low chlorinated PCBs and the cancer risk of dioxin-like PCBs in the study area and similar e-waste recycling areas

De Novo Assembly and Characterization of Narrow-Ridged Finless Porpoise Renal Transcriptome and Identification of Candidate Genes Involved in Osmoregulation

During the evolutionary transition from land to water, cetaceans have undergone numerous critical challenges, with osmoregulation being the major one. Two subspecies of the narrow-ridged finless porpoise (Neophocaena asiaeorientalis), the freshwater Yangtze finless porpoise (N. a. asiaeorientalis, NAA) and the marine East Asian finless porpoise (N. a. sunameri, NAS), provide excellent subjects to understand the genetic basis of osmoregulatory divergence between freshwater and marine mammals. The kidney plays an important and well-established role in osmoregulation in marine mammals and thus, herein, we utilized RNA-seq to characterize the renal transcriptome and preliminarily analyze the divergence between the NAA and the NAS. Approximately 48.98 million clean reads from NAS and 49.40 million clean reads from NAA were obtained by RNA-Seq. And 73,449 (NAS) and 68,073 (NAA) unigenes were assembled. Among these annotations, 22,231 (NAS) and 21,849 (NAA) unigenes were annotated against the NCBI nr protein database. The ion channel complex GO term and four pathways were detected as relevant to osmoregulation by GO and KEGG pathway classification of these annotated unigenes. Although the endangered status of the study species prevented analysis of biological replicates, we identified nine differentially expressed genes (DEGs) that may be vital in the osmoregulation of the narrow-ridged finless porpoise and worthwhile for future studies. Of these DEGs, the differential expression and distribution of the aquaporin-2 (AQP2) in the collecting duct were verified using immunohistochemical experiments. Together, this work is the first report of renal transcriptome sequencing in cetaceans, and it will provide a valuable resource for future molecular genetics studies on cetacean osmoregulation

Identification of differentially expressed genes in Oncomelania hupensis chronically infected with Schistosoma japonicum

Oncomelania hupensis is the unique intermediate host of Schistosoma japonicum. The schistosome-snail interaction is biomedically important. To identify differentially expressed transcripts in O. hupensis chronically infected with S. japonicum, suppression subtractive hybridization (SSH) was used to construct a cDNA library in each direction for transcripts that are more abundantly enriched in head-foot part of the infected O. hupensis and for those that are more abundantly enriched in the uninfected, as head-foot part contains hemocytes and hemolymph which are associated with the snail internal defense system. After differential screening, 39 transcripts were identified, including nine and 30 transcripts enriched in infected and uninfected snails, respectively. Some of the transcripts have similar homology to available sequences in current databases, including transposase, caveolin-like protein, pancreatic trypsin inhibitor-like protein, prosaposin, glutathione s-transferase (GST), and several hypothetical proteins, while most of the transcripts do not match with any sequences in available databases. The identified transcripts were involved functionally in cell growth, metabolism, signal transduction, and immune responses. Two forward library transcripts and 11 reverse library transcripts were selected for real-time PCR, and 10 of them were confirmed to be consistent with the SSH results. It is intriguing to continue functional studies for some genes such as pancreatic trypsin inhibitor; a hypothetical protein (HS576367) related to calcium ion binding; GST; and several unknown proteins (HS576353 and HS576355). These identified differentially expressed genes may be key targets for understanding the molecular mechanism of co-existence during which the snail is unable to rid itself of the schistosome in chronic infection stage. (C) 2012 Elsevier Inc. All rights reserved.Oncomelania hupensis is the unique intermediate host of Schistosoma japonicum. The schistosome-snail interaction is biomedically important. To identify differentially expressed transcripts in O. hupensis chronically infected with S. japonicum, suppression subtractive hybridization (SSH) was used to construct a cDNA library in each direction for transcripts that are more abundantly enriched in head-foot part of the infected O. hupensis and for those that are more abundantly enriched in the uninfected, as head-foot part contains hemocytes and hemolymph which are associated with the snail internal defense system. After differential screening, 39 transcripts were identified, including nine and 30 transcripts enriched in infected and uninfected snails, respectively. Some of the transcripts have similar homology to available sequences in current databases, including transposase, caveolin-like protein, pancreatic trypsin inhibitor-like protein, prosaposin, glutathione s-transferase (GST), and several hypothetical proteins, while most of the transcripts do not match with any sequences in available databases. The identified transcripts were involved functionally in cell growth, metabolism, signal transduction, and immune responses. Two forward library transcripts and 11 reverse library transcripts were selected for real-time PCR, and 10 of them were confirmed to be consistent with the SSH results. It is intriguing to continue functional studies for some genes such as pancreatic trypsin inhibitor; a hypothetical protein (HS576367) related to calcium ion binding; GST; and several unknown proteins (HS576353 and HS576355). These identified differentially expressed genes may be key targets for understanding the molecular mechanism of co-existence during which the snail is unable to rid itself of the schistosome in chronic infection stage. (C) 2012 Elsevier Inc. All rights reserved