Oil pollution in the North Sea—a microbiological point of view

In this study we determined oil degradation rates in the North Sea under most natural conditions. We used the heavy fuel oil, Bunker C, the major oil pollutant of the North Sea, as the model oil. Experiments were conducted in closed systems with water sampled during winter and repeated under identical conditions with water collected during summer. No nitrogen or phosphorous was added and conditions were chosen such that neither oxygen nor nutrients, present in the water, would become limiting during the experiments. We detected a fourfold increased degradation rate for water samples taken in summer (18°C water temperature) as compared to water sampled in winter (4°C water temperature). Under the assumption that biodegradation of oil can be regarded as a Michaelis-Menten type kinetic reaction, the kinectic constants Vmax and KM were determined for oil biodegradation at 4°C and 18°C. At both temperatures KM was about 40 ppm, whereas Vmax was 3–4 times higher at 18°C. From both Vmax and the results of fermentation studies, we determined the maximum rates of Bunker C oil degradation in the North Sea as ∼20 g m−3a−1 at 4°C in winter and 60–80 g m−3a−1 at 18°C in summer. Furthermore, while over 25% of the oil was degraded within 6 weeks in summer, only 6.6% of the oil was degraded in winter. A higher incubation temperature in winter (18°C) increased both the rate and the percentage of oil degraded, but degradation did not reach the level obtained during the summer. While these data reflect the oxidation only of the hydrocarbons, we conducted experiments directly in the open sea to determine the contribution of abiotic factors to oil removal. Approximately 42% of the oil was lost within 6 weeks under these conditions in summer and 65% in winter. However, GC-MS analysis of the recovered oil showed no significant change in the alkane pattern that would indicate enhanced degradation. Thus, mainly abiotic factors such as erosion and dispersion rather than degradation were responsible for enhanced oil removal. Especially the high loss during winter can be attributed to frequent storms resulting in greater dispersion. In conclusion, the higher oil degrading potential of the microbial population in the North Sea was represented by a four times faster oil degradation during the summer. In-situ experiments showed that abiotic factors can have an equal (summer) or even higher (winter) impact on oil removal

A bacterial facultative parasite of Gracilaria conferta

Bacterial epiphytes of Gracilaria conferta were quantified. Saprophytic bacteria reached 350 times and agar degraders 25000 times higher numbers g-1 algal wet wt on tissues infected with the 'white tips disease', as compared to healthy tissues. A bacterial inducing agent of the 'white tips disease' was detected. Addition of 10(2) to 10(3) cells of this isolate ml-1 medium led to increased rates of infection. This effect did not occur if the isolate was autoclaved before addition. The virulent bacteria could always be isolated from infected tissues. It frequently, but not always, infected G. conferta and should be regarded as a facultative parasite. Several factors influenced the disease development. Temperatures above 20-degrees-C, in combination with photon flux densities of more than 200 muE m-2 s-1, increased the rate of infection. Relatively low amounts (more than 25 mug ml-1) of certain organic nutrients (peptone and yeast extract) led to strong manifestations of the disease. Addition of agar did not cause any symptoms, while 5 mg l-1 of the antibiotic rifampicin prevented the alga from being infected

Saturn integrated circuit reliability test program Quarterly progress report, Jul. - Sep. 1966

Saturn integrated circuit reliability tests performed to improve failure mode screenin

DIAGNÓSTICO DA QUALIDADE DA ÁGUA AO LONGO DE UM CANAL DE CONCRETO: UM ESTUDO DE CASO DO CANAL DO SERTÃO ALAGOANO - BRASIL

Para atender a demanda, a transferência de água de rios por canal é uma prática comum no Nordeste brasileiro. O Canal do Sertão Alagoano capta água do rio São Francisco (no reservatório Apolônio Sales) para abastecer municípios do estado de Alagoas. O objetivo deste trabalho foi analisar a evolução de parâmetros físico-químicos da água (temperatura, pH, turbidez, condutividade, dureza, sulfatos, cloretos, nitrogênio total e fósforo total) ao longo dos 29 km iniciais. Foram realizadas duas coletas no período seco em 10 pontos. Por meio do teste não-paramétrico MannWhitney, evidenciou-se que temporalmente as duas coletas são significativamente diferentes para todos os parâmetros, mesmo sendo ambas realizadas no período seco. Longitudinalmente, nas duas coletas, temperatura, pH e condutividade, foram significativamente diferentes entre o início e o final dos 29 km, apresentando uma tendência crescente nos valores. Quanto à qualidade, conforme a Resolução 357/2005 do CONAMA, a água do Canal apresentou valores dentro da Classe 1, com exceção do fósforo total

UV radiation enhanced oxygen vacancy formation caused by the PLD plasma plume

Pulsed Laser Deposition is a commonly used non-equilibrium physical deposition technique for the growth of complex oxide thin films. A wide range of parameters is known to influence the properties of the used samples and thin films, especially the oxygen-vacancy concentration. One parameter has up to this point been neglected due to the challenges of separating its influence from the influence of the impinging species during growth: the UV-radiation of the plasma plume. We here present experiments enabled by a specially designed holder to allow a separation of these two influences. The influence of the UV-irradiation during pulsed laser deposition on the formation of oxygen-vacancies is investigated for the perovskite model material SrTiO3. The carrier concentration of UV-irradiated samples is nearly constant with depth and time. By contrast samples not exposed to the radiation of the plume show a depth dependence and a decrease in concentration over time. We reveal an increase in Ti-vacancy–oxygen-vacancy-complexes for UV irradiated samples, consistent with the different carrier concentrations. We find a UV enhanced oxygen-vacancy incorporation rate as responsible mechanism. We provide a complete picture of another influence parameter to be considered during pulsed laser depositions and unravel the mechanism behind persistent-photo-conductivity in SrTiO3

Neutralization of SARS-CoV-2 by highly potent, hyperthermostable, and mutation-tolerant nanobodies

Monoclonal anti-SARS-CoV-2 immunoglobulins represent a treatment option for COVID-19. However, their production in mammalian cells is not scalable to meet the global demand. Single-domain (VHH) antibodies (also called nanobodies) provide an alternative suitable for microbial production. Using alpaca immune libraries against the receptor-binding domain (RBD) of the SARS-CoV-2 Spike protein, we isolated 45 infection-blocking VHH antibodies. These include nanobodies that can withstand 95°C. The most effective VHH antibody neutralizes SARS-CoV-2 at 17–50 pM concentration (0.2–0.7 µg per liter), binds the open and closed states of the Spike, and shows a tight RBD interaction in the X-ray and cryo-EM structures. The best VHH trimers neutralize even at 40 ng per liter. We constructed nanobody tandems and identified nanobody monomers that tolerate the K417N/T, E484K, N501Y, and L452R immune-escape mutations found in the Alpha, Beta, Gamma, Epsilon, Iota, and Delta/Kappa lineages. We also demonstrate neutralization of the Beta strain at low-picomolar VHH concentrations. We further discovered VHH antibodies that enforce native folding of the RBD in the E. coli cytosol, where its folding normally fails. Such “fold-promoting” nanobodies may allow for simplified production of vaccines and their adaptation to viral escape-mutations

Nonhuman humanitarianism: when ‘AI for good’ can be harmful

Artificial intelligence (AI) applications have been introduced in humanitarian operations in order to help with the significant challenges the sector is facing. This article focuses on chatbots which have been proposed as an efficient method to improve communication with, and accountability to affected communities. Chatbots, together with other humanitarian AI applications such as biometrics, satellite imaging, predictive modelling and data visualisations, are often understood as part of the wider phenomenon of ‘AI for social good’. The article develops a decolonial critique of humanitarianism and critical algorithm studies which focuses on the power asymmetries underpinning both humanitarianism and AI. The article asks whether chatbots, as exemplars of ‘AI for good’, reproduce inequalities in the global context. Drawing on a mixed methods study that includes interviews with seven groups of stakeholders, the analysis observes that humanitarian chatbots do not fulfil claims such as ‘intelligence’. Yet AI applications still have powerful consequences. Apart from the risks associated with misinformation and data safeguarding, chatbots reduce communication to its barest instrumental forms which creates disconnects between affected communities and aid agencies. This disconnect is compounded by the extraction of value from data and experimentation with untested technologies. By reflecting the values of their designers and by asserting Eurocentric values in their programmed interactions, chatbots reproduce the coloniality of power. The article concludes that ‘AI for good’ is an ‘enchantment of technology’ that reworks the colonial legacies of humanitarianism whilst also occluding the power dynamics at play

Conviviality and Parallax in David Olusoga’s Black and British: A Forgotten History

Through examining the BBC television series, Black and British: A Forgotten History, written and presented by the historian David Olusoga, and in extending Paul Gilroy’s assertion that the everyday, banality of living with difference is now an ordinary part of British life, this article considers how Olusoga’s historicization of the black British experience reflects a convivial rendering of UK multiculture. In particular, when used alongside Žižek’s notion of parallax, it is argued that understandings of convivial culture can be supported by a historical importance that deliberately ‘shocks’ and, subsequently dislodges, popular interpretations of the UK’s ‘white past’. Notably, it is parallax which puts antagonism, strangeness and ambivalence at the heart of contemporary depictions of convivial Britain, with the UK’s cultural differences located in the ‘gaps’ and tensions which characterize both its past and present. These differences should not be feared but, as a characteristic part of our convivial culture, should be supplemented with historical analyses that highlight but, also, undermine, the significance of cultural differences in the present. Consequently, it is suggested that if the spontaneity of conviviality is to encourage openness, then, understandings of multiculturalism need to go beyond reification in order to challenge our understandings of the past. Here, examples of ‘alterity’ are neither ‘new’ nor ‘contemporary’ but, instead, constitute a fundamental part of the nation’s history: of the ‘gap’ made visible in transiting past and present