High power cladding-pumped Er3+/Yb3+ fiber amplifiers: technologies, performances and impact of nonlinear effects

Yb³⁺-sensitized Er³⁺-doped fibers are attracting increasing interest because of the high achievable performances, such as high gain and pump efficiency. High output power can be obtained from a double clad (dc) Er³⁺/Yb³⁺ co-doped fiber pumped with broad area high power pump laser diodes. The principle of amplification in this kind of co-doped fibers is presented in this paper. Different solutions for the injection of pump power in the 1^st-cladding have been described. The energy transfer mechanism in a Er³⁺/Yb³⁺ co-doped system including cooperative-upconversion process is explained. Gain and absorption properties ofdc fibers have been determined experimentally and inserted in a theoretical amplifier model. Good agreement between measurements and modelling has been obtained. Hybrid Er³⁺-Er³⁺/Yb³⁺ amplifier architectures are suitable to obtain + 30 dBm output power. The gain bandwidth is in the 1535–1565 nm range for single wavelength operation. A spectral gain flatness is observed in a reduced C-bandWDM operation (i.e. 1545–1565 nm) without gain-flattening filter. Nonlinear effects such as the optical Kerr effect or the stimulated Brillouin scattering can be observed in high power amplifiers due to the high output peak power confined in the fiber core. These two nonlinear phenomena have been investigated for different high power amplifier configurations. Numerical modelling have also confirmed the observed signal distortions.     

Establishment of the varietal volatile profile of musts from white Vitis vinifera L. varieties

Musts from four white Vitis vinifera L. varieties of Bairrada Appellation (Fernão‐Pires, Bical, Cerceal and Arinto) were analysed over two harvests (1998 and 1999). The free volatile components were extracted using a liquid–liquid continuous method and were analysed by gas chromatography/mass spectrometry. The potential volatile compounds (PVC) were determined after a heat treatment followed by an enzymatic treatment. The PVC fraction contained the compounds released by the enzymes from the glycosidically linked components plus the compounds produced by the heat treatment at the must pH (3.2) as well as compounds arising from the thermal degradation of sugars. Based on three varietal chemical groups, namely terpenoids, C₁₃ norisoprenoids and aromatic alcohols, the volatile profile of each of the four varieties was established, which allowed their aroma potential to be defined. Fernão‐Pires exhibited a profile significantly different from those of the other varieties, with a higher number and concentration of volatile compounds. As a consequence of the fact that the four varieties exhibit different volatile composition patterns (different components and different distributions between free and PVC forms), winemaking technologies should be specifically developed for each variety for the improvement of wine aroma quality. Owing to the complexity of the data, including the harvest effect, a contrast data pre‐treatment was applied before the utilisation of principal component analysis. The results suggest that it is possible to establish markers (volatiles) for the characterisation of must varieties independently of the harvest effect. Copyright © 2007 Society of Chemical Industry     

ATR‐FTIR spectroscopy and chemometric analysis applied to discrimination of landrace maize flours produced in southern Brazil

This work aims at discriminating flours of 26 maize landraces from southern Brazil, by using the Attenuated Total Reflection Fourier Transform Infrared (ATR‐FTIR) spectroscopy and chemometrics (principal components analysis – PCA). PCA applied to the FTIR spectra in the 3‐600 (whole spectrum) and 1650–1500 cm^?1 (fingerprint region of proteins) spectral windows clearly discriminated the Amarelão landrace. Quantitative and semi‐qualitative analysis of proteins showed a wide range among the fractions, mainly of prolamine (13.47–28.43 g Kg^?1) and glutelin (5.57–30.98 g Kg^?1) contents. Pixurum 6, Pixurum 5, and MPA1 landraces are of superior nutritional value for their albumin, globulin, and glutelin contents. PCA of the spectral dataset in the fingerprint region to carbohydrates (1200–950 and 1065–950 cm^?1) also including commercial standards of amylose and amylopectin was able in separating the Moroti genotype, which grouped with the amylopectin standard. Thus, ATR‐FTIR and PCA showed to be useful tools for the quick screening and discrimination of maize with distinct chemical composition.     

Alkaloids in the human food chain--natural occurrence and possible adverse effects

Alkaloid-containing plants are an intrinsic part of the regular Western diet. The present paper summarizes the occurrence of alkaloids in the food chain, their mode of action and possible adverse effects including a safety assessment. Pyrrolizidine alkaloids are a reason for concern because of their bioactivation to reactive alkylating intermediates. Several quinolizidine alkaloids, β-carboline alkaloids, ergot alkaloids and steroid alkaloids are active without bioactivation and mostly act as neurotoxins. Regulatory agencies are aware of the risks and have taken or are considering appropriate regulatory actions for most alkaloids. These vary from setting limits for the presence of a compound in feed, foods and beverages, trying to define safe upper limits, advising on a strategy aiming at restrictions in use, informing the public to be cautious or taking specific plant varieties from the market. For some alkaloids known to be present in the modern food chain, e.g., piperine, nicotine, theobromine, theophylline and tropane alkaloids risks coming from the human food chain are considered to be low if not negligible. Remarkably, for many alkaloids that are known constituents of the modern food chain and of possible concern, tolerable daily intake values have so far not been defined.     

Dehalococcoides ethenogenes strain 195 reductively dechlorinates diverse chlorinated aromatic pollutants

Dehalococcoides ethenogenes strain 195 dechlorinates tetrachloroethene to vinyl chloride and ethene, and its genome has been found to contain up to 17 putative dehalogenase gene homologues, suggesting diverse dehalogenation ability. We amended pure or mixed cultures containing D. ethenogenes strain 195 with 1,2,3,4-tetrachlorodibenzo-p-dioxin, 2,3,7,8-tetrachlorodibenzo-p-dioxin, 2,3-dichlorodibenzo-p-dioxin, 1,2,3,4-tetrachlorodibenzofuran, 2,3,4,5,6-pentachlorobiphenyl, 1,2,3,4-tetrachloronaphthalene, various chlorobenzenes, or a mixture of 2-, 3-, and 4-chlorophenol to determine the dehalogenation ability. D. ethenogenes strain 195 dechlorinated 1,2,3,4-tetrachlorodibenzo-p-dioxin to a mixture of 1,2,4-trichlorodibenzo-p-dioxin and 1,3-dichlorodibenzo-p-dioxin. 2,3,4,5,6- Pentachlorobiphenyl was dechlorinated to 2,3,4,6- and/or 2,3,5,6-tetrachlorobiphenyl and 2,4,6-trichlorobiphenyl. 1,2,3,4-Tetrachloronaphthalene was dechlorinated primarily to an unidentified dichloronaphthalene congener. The predominant end products from hexachlorobenzene dechlorination were 1,2,3,5-tetrachlorobenzene and 1,3,5-trichlorobenzene. We did not detect dechlorination daughter products from monochlorophenols, 2,3-dichlorodibenzo-p-dioxin or 2,3,7,8- tetrachlorodibenzo-p-dioxin. D. ethenogenes strain 195 has the ability to dechlorinate many different types of chlorinated aromatic compounds, in addition to its known chloroethene respiratory electron acceptors. Remediation of sediments contaminated with aromatic halogenated organic pollutants such as polychlorinated biphenyls and polychlorinated dibenzo-p-dioxins could require billions of dollars in the coming years. Harnessing microorganisms such as Dehalococcoides spp. that detoxify these compounds via removal of halogens may lead to cost-effective biotechnological approaches for remediation.     

Inulin Improves Diet-Induced Hepatic Steatosis and Increases Intestinal Akkermansia Genus Level

Hepatic steatosis is characterized by triglyceride accumulation within hepatocytes in response to a high calorie intake, and it may be related to intestinal microbiota disturbances. The prebiotic inulin is a naturally occurring polysaccharide with a high dietary fiber content. Here, we evaluate the effect of inulin on the intestinal microbiota in a non-alcoholic fatty liver disease model. Mice exposed to a standard rodent diet or a fat-enriched diet, were supplemented or not, with inulin. Liver histology was evaluated with oil red O and H&E staining and the intestinal microbiota was determined in mice fecal samples by 16S rRNA sequencing. Inulin treatment effectively prevents liver steatosis in the fat-enriched diet group. We also observed that inulin re-shaped the intestinal microbiota at the phylum level, were Verrucomicrobia genus significantly increased in the fat-diet group; specifically, we observed that Akkermansia muciniphila increased by 5-fold with inulin supplementation. The family Prevotellaceae was also significantly increased in the fat-diet group. Overall, we propose that inulin supplementation in liver steatosis-affected animals, promotes a remodeling in the intestinal microbiota composition, which might regulate lipid metabolism, thus contributing to tackling liver steatosis.     

Optimization of BWR fuel lattice enrichment and gadolinia distribution using genetic algorithms and knowledge

An optimization methodology based on the Genetic Algorithms (GA) method was developed for the design of radial enrichment and gadolinia distributions for boiling water reactor (BWR) fuel lattices. The optimization algorithm was linked to the HELIOS code to evaluate the neutronic parameters included in the objective function. The goal is to search for a fuel lattice with the lowest average enrichment, which satisfy a reactivity target, a local power peaking factor (PPF), lower than a limit value, and an average gadolinia concentration target. The methodology was applied to the design of a 10 × 10 fuel lattice, which can be used in fuel assemblies currently used in the two BWRs operating at Mexico. The optimization process showed an excellent performance because it found forty lattice designs in which the worst one has a better neutronic performance than the reference lattice design. The main contribution of this study is the development of an efficient procedure for BWR fuel lattice design, using GA with an objective function (OF) which saves computing time because it does not require lattice burnup calculations.     

Polycystin-1 Is a Crucial Regulator of BIN1 Expression and T-Tubule Remodeling Associated with the Development of Dilated Cardiomyopathy

Cardiomyopathy is commonly observed in patients with autosomal dominant polycystic kidney disease (ADPKD), even when they have normal renal function and arterial pressure. The role of cardiomyocyte polycystin-1 (PC1) in cardiovascular pathophysiology remains unknown. PC1 is a potential regulator of BIN1 that maintains T-tubule structure, and alterations in BIN1 expression induce cardiac pathologies. We used a cardiomyocyte-specific PC1-silenced (PC1-KO) mouse model to explore the relevance of cardiomyocyte PC1 in the development of heart failure (HF), considering reduced BIN1 expression induced T-tubule remodeling as a potential mechanism. PC1-KO mice exhibited an impairment of cardiac function, as measured by echocardiography, but no signs of HF until 7–9 months of age. Of the PC1-KO mice, 43% died suddenly at 7 months of age, and 100% died after 9 months with dilated cardiomyopathy. Total BIN1 mRNA, protein levels, and its localization in plasma membrane-enriched fractions decreased in PC1-KO mice. Moreover, the BIN1 + 13 isoform decreased while the BIN1 + 13 + 17 isoform was overexpressed in mice without signs of HF. However, BIN1 + 13 + 17 overexpression was not observed in mice with HF. T-tubule remodeling and BIN1 score measured in plasma samples were associated with decreased PC1-BIN1 expression and HF development. Our results show that decreased PC1 expression in cardiomyocytes induces dilated cardiomyopathy associated with diminished BIN1 expression and T-tubule remodeling. In conclusion, positive modulation of BIN1 expression by PC1 suggests a novel pathway that may be relevant to understanding the pathophysiological mechanisms leading to cardiomyopathy in ADPKD patients.     

PMSM DTC系统逆变器故障的模糊神经网络诊断

针对永磁同步电机(PMSM)直接转矩控制(DTC)系统中常见的电力电子逆变器故障,提出了一种基于智能策略的诊断方法。根据PMSM DTC系统逆变器故障的特性,建立了一个自适应神经模糊网络的模型,选择PMSM的电流量作为故障检测和诊断的信号源,对系统正常及故障状态下的电流特性进行了分析,并利用训练好的模糊神经网络进行逆变器的故障诊断。仿真结果表明,该方法仅需检测电机的一相电流便可直接实现逆变器多种常见故障的诊断,摒弃了复杂的信号变换,同时节约了系统成本,保障了故障系统容错策略的实施。