Effect of acid deposition on quantity and quality of dissolved organic matter in soil-water

The aim of this study was to explore how acid deposition may affect the concentration and quality of dissolved organic matter (DOM) in soil-water. This was done by a small-scale acidification experiment during two years where 0.5 × 0.5 m(2) plots were artificially irrigated with water with different sulfuric acid content, and soil-water was sampled using zero-tension lysimeters under the O-horizon. The DOM was characterized using absorbance, fluorescence, and size exclusion chromatography analyses. Our results showed lower mobility of DOM in the high acid treatment. At the same time, there was a significant change in the DOM quality. Soil-water in the high acid treatment exhibited DOM that was less colored, less hydrophobic, less aromatic, and of lower molecular weight, compared to the low acid treatment. This supports the hypothesis that reduction in sulfur deposition is an important driver behind the ongoing brownification of surface waters in many regions.     

Bark as feedstock for dual fluidized bed gasifiers—Operability,efficiency, and economics

The demand for biofuels and biochemicals is expected to increase in the future, which will in turn increase the demand for biomass feedstock. Large gasification plants fueled with biomass feedstock are likely to be a key enabling technology in a resource‐efficient, bio‐based economy. Furthermore, the costs for producing biofuels and biochemicals in such plants could potentially be decreased by utilizing inexpensive low‐grade residual biomass as feedstock. This study investigates the usage of shredded tree bark as a feedstock for the production of biomethane in the GoBiGas demonstration plant in Gothenburg, Sweden, based on a 32 MW_th industrial dual fluidized bed gasification unit. The plant was operated with bark feedstock for 12 000 hours during the period 2014 to 2018. Data from the measurement campaign were processed using a stochastic approach to establish the plant's mass and energy balances, which were then compared with operation of the plant with wood pellets. For this comparison, an extrapolation algorithm was developed to predict plant performance using bark dried to the same moisture content as wood pellets, ie, 8%_w.b. Plant operation with bark feedstock was evaluated for operability, efficiency, and feedstock‐related cost. The gas quality achieved during the test period was similar to that obtained for operation with wood pellets. Furthermore, no significant ash sintering or agglomeration problems were observed more than 750 hours of operation. The calculated biomass‐to‐biomethane efficiency is 43% to 47% (lower heating value basis) for operation with wet bark. However, the predicted biomass‐to‐biomethane efficiency can be increased to 55%–65% for operation with bark feedstock dried to 8% moisture content, with corresponding feedstock costs in the range of 24.2 to 32.7 EUR/MWh; ie, a cost reduction of about 40% compared with wood pellets.     

di/dt Noise in CMOS Integrated Circuits

This is an overview paper presenting di/dtnoise from a designers perspective. Analysis and circuit designtechniques are presented taking package parasitics into account.The main focus is on digital CMOS design, but analysis and designsuggestions can easily be extended to mixed-mode design.     

Product-service system innovation capabilities: linkages between the fuzzy front end and subsequent development phases

In an attempt to remain competitive, manufacturers increasingly offer integrated product-service systems (PSSs). This transition from physical products to PSSs calls for new ways of working, for example in the product development process. However, so far only limited attention has been put on capabilities needed to succeed with PSS innovation in the very early development phases – often referred to as the fuzzy front end (FFE). This article, therefore, has a dual aim: first, to further our understanding of capabilities for PSS innovation in the FFE, and second, to determine how these capabilities are linked to PSS innovation capabilities needed in subsequent development phases. Empirical data were collected from an ongoing industrial project developing an innovative PSS offering in a large manufacturing company. Individuals connected to the project reported major challenges, both experienced in the FFE and anticipated in later phases, which provided valuable information regarding capabilities needed to succeed with the endeavour. Findings reveal four links of PSS innovation capabilities: (1) adapting vocabulary and mental models to PSS, (2) handling the ‘intangible aspect’, (3) bridging organisational structures, and (4) managing new business models. PSS innovation capabilities in the FFE are also found to be of higher order (dynamic) compared to capabilities in later development phases.     

Mixed valence and superconductivity

Mixed-valence (MV) systems are referred to here as MV-2 and MV-3 depending on whether two or three consecutive valence states are involved. MV-3 systems range from systems with Hubbard U>0, corresponding to a single stable, intermediate valence state, and U<0, corresponding to stable alternating valences differing by two units. Experiments using inelastic neutron scattering or inelastic X-ray scattering show softening of breathing phonon modes in MV systems compared with related systems with a single valence. It is hypothesized that softening is due to coupling between potential energy surfaces, corresponding to differing localizations of the electron. As predicted, softening is larger in the delocalized case. A mechanism for superconductivity is suggested.     

The importance of strong carbon-metal adhesion for catalytic nucleation of single-walled carbon nanotubes

Density functional theory is used to show that the adhesion between single-walled carbon nanotubes (SWNTs) and the catalyst particles from which they grow needs to be strong to support nanotube growth. It is found that Fe, Co, and Ni, commonly used to catalyze SWNT growth, have larger adhesion strengths to SWNTs than Cu, Pd, and Au and are therefore likely to be more efficient for supporting growth. The calculations also show that to maintain an open end of the SWNT it is necessary that the SWNT adhesion strength to the metal particle is comparable to the cap formation energy of the SWNT end. This implies that the difference between continued and discontinued SWNT growth to a large extent depends on the carbon-metal binding strength, which we demonstrate by molecular dynamics (MD) simulations. The results highlight that first principles computations are vital for the understanding of the binding strength's role in the SWNT growth mechanism and are needed to get accurate force field parameters for MD.     

Particulate platform for bioluminescent immunosensing

The present study examines pyruvate kinase-conjugated antibodies for potential use in ELISA applications. The conjugates had an acceptable stability, and the coupling inflicted only minor impairment on the kinase activity. To mimic the setup of an immunoassay under development, a test antigen (BSA) was attached to polystyrene nanoparticles. This arrangement was found to be suitable as solid support for presentation of antigens in sensitive bioluminescence assays. The nanoparticles were well characterized in terms of protein surface load and were used to establish the number of conjugate complexes needed to generate a detectable signal. Under the biochemical conditions employed here, the detection limit of the pyruvate kinase conjugate lies in the femtomole range.     

Incoupling waveguide hologram with reduced polarization sensitivity

An incoupling waveguide hologram (IWGH) with significantly reduced polarization sensitivity was designed and fabricated in InP for 1550 nm wavelength. The IWGH couples the light from an optical fiber, irrespectively of the state of polarization, into the InP waveguide and simultaneously focuses it to a desired position in the waveguide. Conventional IWGHs are strongly polarization sensitive with a measured 19 dB difference in the incoupling efficiency between the TE and TM mode. In contrast, although some design parameters turned out to be slightly in error, the fabricated IWGHs designed for reduced polarization sensitivity exhibited a 3.1 dB difference in the incoupling efficiency between the TE and TM modes     

Computational strategy for capturing localization in undrained soil

 The paper concerns the issue of progressive development of shear bands in drained and undrained porous media. The main focus is on the design of an overall numerical algorithm to solve the coupled set of non-linear FE-equations that arise from the embedded band approach. In particular, we are concerned with the proper numerical treatment of the condition for onset of localization in conjunction with ductile material failure, whereby failure occurs after significant amount of plastic deformation. In order to arrive at the proper design of the algorithm, we resort to a staggering between the continuous (global) problem and the discontinuous (element) problems. At the application to the numerical examples, the algorithm is shown to work well in terms its ability to capture onset of localization as well as post-localized behavior in conjunction with ductile material failure characteristics. Received 27 October 1997     

Acetylation of solid wood using microwave heating Part 2. Experiments in laboratory scale

r  × t × l) of the same origin were acetylated separately, but under the same conditions in the microwave reactor. The variation in acetyl content both within and between the samples was less than 2% units. In general, a somewhat higher acetyl content was obtained in the middle of the acetylated wood than in the outer part of it. Microwave energy was also shown to be efficient in the removal of excess acetic anhydride and by-product acetic acid by evaporation under vacuum. During the vacuum step, about 70% of the chemicals could be removed within the first 30 minutes. Pine and spruce wood samples acetylated for 2 hours at 130 °C followed by a vacuum step for two hours at 120 °C, obtained an acetyl content of about 17% and the content of residual chemicals was about 3% calculated on a basis of dry acetylated wood. The temperature in the wood samples could be maintained at about 130 °C even at very low contents of residual excess chemicals without any formation of hot spots.

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r  × t × l) vom gleichen Ursprung nacheinander und unter gleichen Bedingungen acetyliert wurden. Die Variation des Acetylgehaltes lag sowohl innerhalb der einzelnen Proben, als auch zwischen den Proben unterhalb 2%. Allgemein war der acetylgehalt im Probeninneren etwas h?her, als in den ?u?eren Bereichen. Die Mikrowellenbestrahlung erlaubte zudem eine effektive Entfernung des überschüssigen Acetanhydrids und anderer Nebenprodukte durch Vakuumverdampfung. Unter Vakuum konnten ca. 70% der Chemikalien innerhalb von 30 min. entfernt werden. Keifern- und Fichtenholz enthielt nach 2-stündiger Acetylierung bei 130 °C und 2-stündiger Vakuumbehandlung bei 120 °C einen Acetylgehalt von 17%. Der Gehalt an restlichen Chemikalien betrug 3%, bezogen auf trockenes, acetyliertes Holz. Die Temperatur in den Holzproben konnte bei 130 °C gehalten werden, ohne Ausbildung von hei?en Zonen, auch wenn nur geringe überschüsse von Reaktionsmitteln verwendet wurden.