Metal complexation properties of freshwater dissolved organic matter are explained by its aromaticity and by anthropogenic ligands

Dissolved organic matter (DOM) in surface waters affects the fate and environmental effects of trace metals. We measured variability in the Cd, Cu, Ni, and Zn affinity of 23 DOM samples isolated by reverse osmosis from freshwaters in natural, agricultural, and urban areas. Affinities at uniform pH and ionic composition were assayed at low, environmentally relevant free Cd, Cu, Ni, and Zn activities. The C-normalized metal binding of DOM varied 4-fold (Cu) or about 10-fold (Cd, Ni, Zn) among samples. The dissolved organic carbon concentration ranged only 9-fold in the waters, illustrating that DOM quality is an equally important parameter for metal complexation as DOM quantity. The UV-absorbance of DOM explained metal affinity only for waters receiving few urban inputs, indicating that in those waters, aromatic humic substances are the dominant metal chelators. Larger metal affinities were found for DOM from waters with urban inputs. Aminopolycarboxylate ligands (mainly EDTA) were detected at concentrations up to 0.14 μM and partly explained the larger metal affinity. Nickel concentrations in these surface waters are strongly related to EDTA concentrations (R2=0.96) and this is underpinned by speciation calculations. It is concluded that metal complexation in waters with anthropogenic discharges is larger than that estimated with models that only take into account binding on humic substances.     

Material Selection for Cryogenic Support Structures

Design specifications for the support structures of low temperature instrumentation often call for low thermal conductivity between temperature stages, high stiffness, and specific load bearing capabilities. While overall geometric design plays an important role in both overall stiffness and heat conduction between stages, material selection can affect a structure’s properties significantly. In this contribution, we suggest and compare several alternative materials to the current standard materials for building cryogenic support structures.     

Explicit strategies for incompressible fluid‐structure interaction problems: Nitsche type mortaring versus Robin–Robin coupling

We discuss explicit coupling schemes for fluid‐structure interaction problems where the added mass effect is important. In this paper, we show the close relation between coupling schemes by using Nitsche's method and a Robin–Robin type coupling. In the latter case, the method may be implemented either using boundary integrals of the stresses or the more conventional discrete lifting operators. Recalling the explicit method proposed in Comput. Methods Appl. Mech. Engrg. 198(5‐8):766–784, 2009, we make the observation that this scheme is stable under a hyperbolic type CFL condition, but that optimal accuracy imposes a parabolic type CFL conditions because of the splitting error. Two strategies to enhance the accuracy of the coupling scheme under the hyperbolic CFL‐condition are suggested, one using extrapolation and defect‐correction and one using a penalty‐free non‐symmetric Nitsche method. Finally, we illustrate the performance of the proposed schemes on some numerical examples in two and three space dimensions. Copyright © 2013 John Wiley & Sons, Ltd.     

Über die Konfiguration einiger durch Anlagerung von Mercaptoverbindungen an Acetylendicarbonsäure hergestellten Verbindungen

The Configuration of Some Compounds Prepared by Addition of Thiols to Acetylene Dicarboxylic Acid The acids RSC(COOH) = CHCOOH 3 with R = HOOCCH₂, HOOCCH(CH₃), C₆H₅, C₆H₅CH₂, p-ClC₆H₄CH₂ and C₆H₅CH(CH₃) have been prepared by addition of thiols RSH to acetylene dicarboxylic acid (alkali salt) in aqueous alkaline solution. It has been shown that only trans-isomers 3 and no cis-isomers 4 are formed. The methyl esters of 3 could be partially isomerized to yield the corresponding cis-esters. No cis-acids could be obtained by saponification of the latter.     

Scheduling in Optical WDM Networks Using Hidden Markov Chain Based Traffic Prediction

This paper presents the design and performance analysis of a predictor-based scheduling algorithm for optical wavelength division multiplexed (WDM) networks. WDM technology provides multiple, simultaneous and independent gigabit-per-second channels on a single fiber. A reservation-based multiple access control (MAC) protocol is considered here for a local area WDM network based on the passive star topology. The MAC protocol schedules reservation requests from the network nodes on the multiple channels. In previous work, we have presented an on-line scheduling algorithm for such a network. We have shown earlier that schedule computation time can significantly affect performance and the scheduling algorithms should be simple for better performance. In this work, we further improve system performance by using a hidden Markov chain based prediction algorithm. The objective here is to reduce the amount of time spent in computing the schedule by predicting traffic requests. Performance analysis based on discrete-event simulation, varying parameters such as number of nodes and channels is presented. The results show that the error of prediction is reasonable for most cases: more than 70% of the time, the error between actual request and predicted request is less than 20%. Network throughput is higher with the proposed prediction algorithm due to pipelining of schedule computation.     

New procedure for improving precision and accuracy of instrumental color measurements of beef

The surface layers of steaks from bovine M. semimembranosus were prepared to have deoxy- (DMb), oxy- (OMb) and metmyoglobin (MMb) states using either chemicals (CHEM) or oxygen partial pressure packaging (OPP). Ninety-six different meat surface areas were measured in reflectance mode (400-1100 nm) for each preparation method. Reflectance spectra were converted to absorbance (A) and then transformed by Kubelka-Munk transformation (K/S) and/or extended multiplicative scatter correction (EMSC). Transformed spectra of prepared pure states were used to make calibration models of MMb, DMb and OMb using either selected wavelengths (SW) or partial least square (PLS) regression. Finally, the predicted myoglobin states were normalized to ensure that no state was <0 or >1 and the sum of all states equal to 1. Multivariate calibrations (i.e. PLS) outperformed the univariate calibrations (i.e. SW). The OPP method of preparing pure states was clearly best for OMb while the CHEM method was best for preparing MMb on fresh meat surfaces. Both preparation methods needed improvement concerning DMb. The CHEM(K/S) SW and the OPP EMSC(A) PLS methods predicted MMb, DMb and OMb with root-mean-square errors of cross validation (RMSECV) equal to 0.08, 0.16 and 0.18 (range 0-1) and 0.04, 0.04 and 0.04 (range 0-1), respectively. This new reflectance protocol has potential for routine meat color measurements.     

Alginate submicron beads prepared through w/o emulsification and gelation with CaCl2 nanoparticles

A simple method for preparing gelled alginate beads with a diameter smaller than 5 μm is described. A 1% alginate solution and a medium chain triglyceride (MCT) oil are used to prepare a water-in-oil (w/o) emulsion, stabilized by polyglycerol polyricinoleate. CaCl₂ nanoparticles with dimensions in the nano-range (6–400 nm), dispersed in MCT oil, are then added to the emulsion. Energy-dispersive X-ray spectroscopy (EDX) and Auger electron spectroscopy (AES) show that these nanoparticles migrate to the emulsion droplet interface, where they dissolve into the aqueous alginate phase and cause gelation, forming beads. Gelation of the beads was confirmed with a novel technique using Congo red as an indicator. A color change occurs upon the addition of CaCl₂ to a Congo red solution and we believe this is due to formation of a Congo red–calcium complex. Scanning electron microscopy shows that alginate beads are mostly in a size range around 1 μm, but beads as small as 200 nm and smaller were also found. Extending the size range of alginate beads into the submicron range, while maintaining relatively mild pH conditions in the interior of the bead, will significantly extend the range of applications for this type of beads.     

Multiwalled Carbon Nanotubes Induce Fibrosis and Telomere Length Alterations

Telomere shortening can result in cellular senescence and in increased level of genome instability, which are key events in numerous of cancer types. Despite this, few studies have focused on the effect of nanomaterial exposure on telomere length as a possible mechanism involved in nanomaterial-induced carcinogenesis. In this study, effects of exposure to multiwalled carbon nanotubes (MWCNT) on telomere length were investigated in mice exposed by intrapleural injection, as well as in human lung epithelial and mesothelial cell lines. In addition, cell cycle, apoptosis, and regulation of genes involved in DNA damage repair were assessed. Exposure to MWCNT led to severe fibrosis, infiltration of inflammatory cells in pleura, and mesothelial cell hyperplasia. These histological alterations were accompanied by deregulation of genes involved in fibrosis and immune cell recruitment, as well as a significant shortening of telomeres in the pleura and the lung. Assessment of key carcinogenic mechanisms in vitro confirmed that long-term exposure to the long MWCNT led to a prominent telomere shortening in epithelial cells, which coincided with G1-phase arrest and enhanced apoptosis. Altogether, our data show that telomere shortening resulting in cell cycle arrest and apoptosis may be an important mechanism in long MWCNT-induced inflammation and fibrosis.     

虚拟化的优势

为了保持企业的业务运营全天候运行,比较有效的实现方法是利用地理冗余在不同的地理位置建立多个数据巾心或站点,把关键任务应用和数据复制到这些中心或站点。