Crosstalk and prefiltering in a two-channel ASK heterodynedetection system without the effect of laser phase noise

The authors present an experimental and theoretical study on the crosstalk in a two-channel amplitude-shift keying (ASK) heterodyne detection system in which the effect of laser phase noise is negligible. Three results are described: (1) the dependence of the crosstalk penalty on the ratio of channel separation to bit rate and on the optical power level of the image band (2) comparison of the measured crosstalk penalities with the ones obtained from a simple model, and (3) the effect of electrical prefiltering on the crosstalk penalty. It is concluded that the channel separation can be as low as four times the bit rate without incurring any crosstalk penalty as long as the optical power of the image band is comparable to the optical power of the desired channel. In addition, electrical prefiltering of the transmitted signals significantly reduces the crosstalk penalty in multichannel ASK heterodyne systems in which the effect of laser phase noise is negligible     

Immobilization of arsenic in a tailings material by ferrous iron treatment

Weathering and internal dissolution processes in mining waste materials may mobilize elevated levels of arsenic (As), contaminating ground and surface waters. Treating the polluted waters with iron oxyhydroxides is an established remediation method. By contrast, little knowledge is available to stabilize As in source materials by treating it with Fe precipitates and, on this way, to prevent the generation of polluted waters. In the present work the efficiency of Fe(II) treatment on As immobilization in a tailings material (TM) was studied with regard to the Fe:As molar ratio, the influence of CaCO3 amendment, and the As desorption at continued intensive leaching of Fe-treated TM. Fe precipitates were created by aerobic treatment of TM with Fe(II)sulfate at several Fe:As molar ratios with or without adding CaCO3, followed by aging the Fe-treated TM. The As retention in the treated tailings was studied by 4-fold elution with water, and the As desorption kinetics was examined by suspension leaching in laboratory microcosms over 3 weeks. Fe(II) treatment of TM reduced the water-extractable total As to <10 microg/L as the Fe:As molar ratio increased from 0 to 8. The water-soluble As of Fe-treated tailings could be reduced to 10-30 microg/L also under conditions of intensive leaching. Stabilizing the pH with CaCO3 resulted in consistently higher As release. The As desorption data followed the first-order kinetics in the early time stages of the desorption whereas at longer times the parabolic diffusion model was valid.     

Repeatered Bidirectional 10 Gb/s–240 km Fiber Transmission Experiment

We report the design and performance evaluation of a novel circulator-based bidirectional optical amplifier. Using this amplifier as a mid-span repeater, we have demonstrated successful bit error rate (BER<10⁻¹³) transmission at 10 Gb/s over 240 km of dispersion shifted fiber in both directions for channel wavelengths at 1557.5 and 1559 nm.     

Pseudo-Starvation Driven Energy Expenditure Negatively Affects Ovarian Follicle Development

In the present investigation, we examined whether a change in whole body energy fluxes could affect ovarian follicular development, employing mice ectopically expressing uncoupling protein 1 in skeletal muscle (UCP1-TG). Female UCP1-TG and wild-type (WT) mice were dissected at the age of 12 weeks. Energy intake and expenditure, activity, body weight and length, and body composition were measured. Plasma insulin, glucose, leptin, plasma fibroblast growth factor 21 (FGF21) and plasma insulin-like growth factor 1 (IGF1) levels were analyzed and ovarian follicle and corpus luteum numbers were counted. IGF1 signaling was analyzed by immunohistochemical staining for the activation of insulin receptor substrate 1/2 (IRS1/2) and AKT. UCP1-TG female mice had increased energy expenditure, reduced body size, maintained adiposity, and decreased IGF1 concentrations compared to their WT littermates, while preantral and antral follicle numbers were reduced by 40% and 60%, respectively. Corpora lutea were absent in 40% of the ovaries of UCP1-TG mice. Phospho-IRS1, phospho-AKT -Ser473 and -Thr308 immunostaining was present in the granulosa cells of antral follicles in WT ovaries, but faint to absent in the antral follicles of UCP1-TG mice. In conclusion, the reduction in circulating IGF1 levels due to the ectopic expression of UCP1 is associated with reduced immunostaining of the IRS1-PI3/AKT pathway, which may negatively affect ovarian follicle development and ovulation.     

In vitro and in vivo Staining Characteristics of Small,Fluorescent, Aβ42‐Binding D‐Enantiomeric Peptides in Transgenic AD Mouse Models

Plaque visualisation : We identified three different D ‐enantiomeric peptides that bind to Alzheimer's amyloid β (Aβ1‐42). As there is currently no definitive pre‐mortem diagnosis for Alzheimer's disease, we investigated the peptides' suitability as molecular probes for in vivo imaging in transgenic mouse models.

     

Key to analyte migration and retention in electrochromatography

This work identifies electrical field-induced concentration polarization (CP) as a key physical mechanism influencing the retention behavior of charged analytes in electrochromatography with fixed beds of porous adsorbent particles. Due to an insufficient screening of intraparticle surface charge, under most general conditions the porous (permeable) particles become charge-selective. CP is caused by coupled mass and charge transport normal to the charge-selective external surface of the permeable particles, which leads to concentration gradients of ionic species in the adjoining interparticle electrolyte solution. Cation-exchange (cation-selective) particles were employed to investigate the influence of applied voltage on the retention factor of counterionic, i.e., positively charged, analytes. It is demonstrated by macroscopic retention data and microscopic studies resolving the CP phenomenon on a particle scale that the dependence of CP on electrical field and mobile-phase ionic strengths is directly reflected in concomitant changes of analyte retention. The CP zones that develop at the interface between interparticle and intraparticle pore space are recognized by charged, but not electroneutral analytes while entering or leaving the particles. The intensity of these convective-diffusion boundary layers (CP zones) depends on the applied field strength and charge selectivity of a particle. Thus, it is the charge-selective transport between the interparticle and intraparticle pore space in packed beds that prevails under typical experimental conditions in electrochromatography and that forms the physical basis for a general electrical field dependence of the retention factor of charged analytes.     

Polycyclic aromatic hydrocarbons (PAH) in various types of tea

For the analysis of the 16 PAH (EFSA-PAH), which are classified as priority for different food groups by the Scientific Committee on Food (SCF) and the Joint FAO/WHO Experts Committee on Food Additives (JECFA) in tea, a sensitive analytical Fast-GC/HRMS method was used. The sample preparation included accelerated solvent extraction (ASE) and the highly automated clean up steps, gel permeation chromatography and solid phase extraction. The analytical parameters, limit of detection (0.01–0.02 μg/kg) and limit of quantification (0.03–0.06 μg/kg), were determined. The repeatability (RSD, n = 3) of different PAH in fruit tea ranged from 0.1 to 11%. It was observed that the total contents of the 16 PAH in tea samples ranged from 14 to 2,662 μg/kg. The analysed tea samples showed an increasing presence of PAH in the following order: herbal and fruit tea (n = 7) < black tea (n = 11) < green tea (n = 11) < white tea (n = 3) < mate-tea (n = 8). The correlation coefficient (R) between BaP and the sum of the 16 EFSA-PAH was established considering the contamination amount in all the 40 tea samples analysed.     

Furan and Methylfurans in Foods: An Update on Occurrence,Mitigation, and Risk Assessment

The acceptance of many foods is related to traditional cooking practices, which create taste and texture and are important to digestibility, preservation, and the reduction of foodborne illnesses. A wide range of compounds are formed during the cooking of foods, a number of these have been shown to lead to adverse effects in classical toxicological models and are known as food processing contaminants (FPC). It is essential that the presence and effects of such compounds alone and in combination within the diet are understood such that proportionate risk management measures can be developed, while taking a holistic view across the whole value chain. Furan and alkylfurans (principally 2‐ and 3‐methylfuran) are highly volatile FPC, which are formed in a wide range of foods at low amounts. The focus of research to‐date has been on those foods, which have been identified to be most consequential in terms of being sources of exposure, namely jarred and canned foods for infants and young children (meals and drinks) and coffee (roast and ground, soluble). This report presents (i) new industry data on the occurrence of furan and methylfurans in selected food categories following previous coffee studies, (ii) the most salient parameters that impact furan formation, and (iii) aspects of importance for the risk assessment.     

RNA Dynamics by NMR Spectroscopy

An ever-increasing number of functional RNAs require a mechanistic understanding. RNA function relies on changes in its structure, so-called dynamics. To reveal dynamic processes and higher energy structures, new NMR methods have been developed to elucidate these dynamics in RNA with atomic resolution. In this Review, we provide an introduction to dynamics novices and an overview of methods that access most dynamic timescales, from picoseconds to hours. Examples are provided as well as insight into theory, data acquisition and analysis for these different methods. Using this broad spectrum of methodology, unprecedented detail and invisible structures have been obtained and are reviewed here. RNA, though often more complicated and therefore neglected, also provides a great system to study structural changes, as these RNA structural changes are more easily defined—Lego like—than in proteins, hence the numerous revelations of RNA excited states.     

Intramammary infusion of a live culture for treatment of bovine mastitis: effect of live lactococci on the mammary immune response

In the accompanying article, we demonstrated that a live culture of Lactococcus lactis compares favourably with antibiotics for treatment of bovine mastitis in two initial field trials. In an effort to explain the mechanism involved, this study investigated the effect of culture administration on the local immune response. In this respect we initially observed that infusion of the live culture Lactococcus lactis stimulated substantial recruitment of polymorphonucleocytes (PMN) and lymphocytes to the udder. For instance, in one assay, quarters infused with the probiotic experienced a dramatic increase (approximately 20,000-fold) in neutrophils over the first 48-h period from an average value of 83.6 cells/ml pre-treatment to 1.78 x 106 cells/ml 48 h post-infusion. Levels of the acute phase proteins haptaglobin and milk amyloid A were also elevated significantly in comparison with controls following infusion of the culture. The results of flow cytometric assays also demonstrated that while infusion of a live lactococcal culture led to an enhanced recruitment of PMN to the udder (from 1.85 x 104 cells/ml pre-infusion to 1.45 x 106 cells/ml 24 h post-infusion) cell-free supernatant from the same culture was not able to do so, indicating that live Lc. lactis can specifically trigger the mammary immune response to elicit PMN accumulation. These results suggest that the mechanism responsible for this probiotic treatment of mastitis is associated with stimulation of the host intramammary immune system.