Ce：YAP晶体中的孪晶缺陷

The twin defects in Ce:YAP were investigated by using synchrotron radiation topography and etch figures. The results show that the twins are {101} and {121} types, and the exchange of neighboring lattice parameters is considered to be the intrinsic factor for twining. Based on such analysis, the twin structure model was established. Otherwise, the growth experiment results show that the abrupt change of growth rate during shoulder formation tends to cause twining.

Effective herding of flatfish by cables with minimal seafloor contact

Otter trawls are very effective at capturing flatfish, but they can affect the seaf loor ecosystems where they are used. Alaska f latf ish trawlers have very long cables (called sweeps) between doors and net to herd fish into the path of the trawl. These sweeps, which ride on and can disturb the seaf loor, account for most of the area affected by these trawls and hence a large proportion of the potential for damage to seaf loor organisms. We examined modifications to otter trawls, such that disk clusters were installed at 9-m intervals to raise trawl sweeps small distances above the seafloor, greatly reducing the area of direct seafloor contact. A critical consideration was whether flatfish would still be herded effectively by these sweeps. We compared conventional and modified sweeps using a twin trawl system and analyzed the volume and composition of the resulting catches. We tested sweeps raised 5, 7.5, and 10 cm and observed no significant losses of flatfish catch until sweeps were raised 10 cm, and those losses were relatively small (5–10%). No size composition changes were detected in the flatfish catches. Alaska pollock (Theragra chalcogramma) were captured at higher rates with two versions of the modified sweeps. Sonar observations of the sweeps in operation and the seaf loor after passage confirmed that the area of direct seafloor contact was greatly reduced by the modified sweep

Heterogeneous catalytic properties of unprecedented m-O-[FeTCPP]2 dimers (H2TCPP = meso-tetra(4-carboxyphenyl)porphyrin): unusual superhyperfine EPR structure

Articulo científico Dalton Transactions

Characterization of cobalt based TPP-bipy coordination polymer

Comunicación a congreso: Póster presentado en The 4th EuCheMS Chemistry Congress (4ECC), Prague, Czech Republic, August 26–30, 2012

Crystal structure and characterization of a new μ-oxo bridged iron porphyrin

Comunicacion a congreso: Póster presentado en VIII Reunión Científica de Bioinorgánica – Bioburgos 2013 (Burgos, 7 al 10 de julio de 2013)

Prevalência da mutação do gene HFE em pacientes com porfiria cutânea tardia do Hospital Universitário Pedro Ernesto- UERJ

A Porfiria Cutânea Tardia (PCT) é uma desordem dermatológica, caracterizada por fotossensibilidade induzida pela circulação de porfirinas que se depositam na pele. Tanto a forma familial como a esporádica são desordens dependentes do acúmulo de ferro. A presença da mutação do gene da Hemocromatose (HFE) é um importante fator de risco para o acúmulo de ferro e pouco se sabe sobre sua prevalência na população brasileira. Da mesma forma, existem poucos relatos a respeito da associação entre mutação do gene HFE e Porfiria Cutânea Tardia. No presente trabalho descrevemos as frequências dos principais alelos e genótipos do gene da Hemocromatose HFE1 em uma coorte de 25 pacientes brasileiros atendidos no HUPE, com Porfiria Cutânea Tardia, durante o período de janeiro 1990 à dezembro 2012, realizando uma correlação da presença desta mutação com a sobrecarga de ferro neste grupo de pacientes. Neste estudo foi utilizado um grupo controle da população fluminense pareado por idade, sexo e grupo étnico informado, para comparar com os dados avaliados dos pacientes com PCT. A pesquisa das mutações genéticas C282Y e H63D do gene da hemocromatose ocorreu através de técnicas de PCR tempo real e e os resultados ratificados por sequenciamento de Sanger. Dos resultados encontrados, não ocorreram diferenças estatísticas significativas nas frequências alélicas e genotípicas das mutações C282Y e H63D entre a coorte com PCT e a população controle. Entretanto, há um forte indício da participação da mutação H63D em um paciente homozigoto, para desenvolvimento da doença, conforme observado na literatura. Dos ensaios bioquímicos, os níveis de ferritina encontrados entre os pacientes portadores de PCT com a mutação H63D foram maiores que os indivíduos sem a mutação.

Versuche zur Verringerung des Dorschbeifanges in Grundschleppnetzen

Bottom otter trawls with cut back upper panels were tested in the fischeries on Baltic Sea flounder and North Sea plaice to reduce cod by-catch. In a first series of experiments on board the fishing research cutter “Clupea” the cod-bycatch was reduced by 63 %. The catch of flounder was by 92 % higher in the cut back trawl. The same trawl with the same experimental set-up achieved aboard the fisching research vessel “Solea” on the other hand a reduction in cod-bycatch by 69 %. The catch of flounder was 23,3 % lesser in the topless trawl, which was in contrast to the “Clupea” trials. In the second series of experiments with the same cut back trawl the splits were shortened to reduce the net opening height from 0,9 m to 0,6 m previously. The cod-bycatch was reduced by 86 % and the catch of flounder was 81 % higher in comparison to the complete trawl. A prototype made of stronger net material but based on the cutting and rigging design of the tested cut back trawl with the shortened splits was tested with commercial twin trawlers. The cod-bycatch was reduced by 82,2 %, the catch of plaice by 43,3 % and the catch of dab by 44,6 % in the comparison to the commercial used trawl TV280. The flounder catch was in the topless trawl 10 % higher. In the North Sea in the comparison to a bottom trawl TV300 the cod by-catch was reduced by 89,8 %, but the catch of plaice and dab were 54 % and 58,7 % lesser. In the next step was a prototype of a normally in the North Sea plaice fisheries used trawl tested with a cut back of 2 m only. The cod catch was reduced by 16,9 % but the plaice catch, however , by 22,3 %. Kurzfassung Schleppnetze mit verkürzten Oberblättern wurden in der Fischerei auf Ostseeflunder und Nordseescholle zur Verringerung des Dorschbeifanges erprobt. In einer ersten Versuchsserie mit dem Forschungskutter „Clupea“ wurde der Dorschbeifang um 63 % reduziert. Die Fänge der Zielart Flunder waren im reduzierten Schleppnetz dagegen um 92 % höher. Das gleiche Schleppnetz mit gleichem Versuchsaufbau erzielte auf dem Fischereiforschungsschiff „Solea“ dagegen eine Reduktion des Dorschbeifanges um 69 %, wobei im Gegensatz zu den „Clupea“-Versuchen der Flunderfang um 23,3 % im reduzierten Netz geringer war. In der zweiten Versuchsserie wurden die Netzstander am reduzierten Schleppnetz verkürzt, um die Netzöffnungshöhe zu verringern. Dadurch wurde der Dorschbeifang in Versuchen mit dem Forschungskutter „Clupea“ um 86 % verringert und die Flunderfänge waren im reduzierten Schleppnetz 81 % höher. Basierend auf dem Zuschnitt des erprobten Schleppnetzes, jedoch aus stärkerem Netzmaterial gefertigt, wurde ein Prototyp auf kommerziellen Doppelnetz-Kuttern erprobt. In der Ostsee wurde in diesen Versuchen der Dorschbeifang um 82,2 %, der Schollenfang um 43,3 % und der Klieschenfang um 44,6 % mit dem im Oberblatt verkürztem Schleppnetz im Vergleich zum Kutterschleppnetz TV280 reduziert. Der Flunderfang war im reduzierten Schleppnetz 10 % höher. Auf der Nordsee wurde mit diesem Versuchsnetz im Vergleich zu einem TV 300 der Kabeljaubeifang um 89,8 % verringert, die Schollenfänge waren jedoch 54 % geringer und die Klieschenfänge 58,7 % geringer als im Vergleichsnetz. In einer weiteren Variante wurde ein in der Nordseeschollenfischerei verwendetes Grundschleppnetz mit 2 m geringfügig im Oberblatt zurückgeschnitten und mit dem Prototyp auf einem Doppelnetz-Heckschlepper verglichen. Der Kabeljaubeifang wurde dadurch um 16,9 % der Schollenfang aber um 22,3 % verringert

Preparação, caracterização e avaliação de nanocompósitos de PBAT/amido de milho e vermiculita organofilizada

Nos últimos 20-30 anos polímeros biodegradáveis vêm sendo estudados e desenvolvidos e atualmente já são comercializados. Contudo, o custo, a processabilidade e algumas propriedades ainda dificultam a penetração desses polímeros no mercado e a competição com as chamadas commodities. Não são poucos os autores que se dedicam a desenvolver aditivos e formulações para superar essas limitações. Desta forma, esta Tese se dedicou ao desenvolvimento de compósitos de Ecobras, fabricado pela Basf e comercializado pela Corn Products, utilizando como carga mineral resíduo da extração da bauxita, no município de Santa Luzia/PB, o qual consiste em sua totalidade de vermiculita. Esta vermiculita foi quimicamente modificada com sais de alquil fosfônio para melhorar a compatibilidade com a matriz polimérica e também espaçar as camadas de aluminossilicato. De fato, a modificação com o brometo de hexadecil tributil fosfônio resultou na esfoliação da vermiculita tornando-a potencialmente apropriada para a obtenção de nanocompósitos. A preparação dos compósitos foi realizada pelo método de intercalação no estado fundido e foram comparadas a utilização da câmara interna de mistura e da mini extrusora de dupla rosca, sendo esta última mais eficaz na dispersão da vermiculita, conforme revelado pela microscopia eletrônica de varredura, difração de raios-X e reometria de placas. O grau de dispersão também foi influenciado pela estrutura química do modificador da vermiculita e pelo teor dessa carga incorporada à matriz. Teores mais elevados levaram a formação de aglomerados, enquanto a modificação da carga implicou na formação de micro e nanocompósitos. Ainda houve alterações das propriedades térmicas com aumento dos valores da temperatura de transição vítrea, de cristalização e fusão, embora o grau de cristalinidade tenha sido mantido. Nitidamente, foram obtidos materiais mais rígidos, com maior módulo e menor capacidade de deformação. Cerca de 58% de perda de massa foi observada para os micro e nanocompósitos obtidos após 17 semanas de enterro em solo simulado para avaliação da biodegradabilidade, valor bem próximo ao Ecobras puro. De modo geral, a incorporação das diferentes vermiculitas retardou nas primeiras semanas a biodegradação, provavelmente em função de modificações na estrutura cristalina, conforme sugerido pelos maiores valores de temperatura de fusão observados durante o acompanhamento do processo de biodegradação. No entanto, após 7 semanas os perfis de biodegradação dos micro e nanocompósitos se aproximaram bastante do Ecobras puro. Desta forma, foi possível nesta Tese obter um nanocompósito de Ecobras com vermiculita modificada com brometo de hexadecil fosfônio utilizando ferramentas comuns de processamento no estado fundido com biodegradabilidade próxima ao polímero de partida, porém mais rígido e menos deformável

Noise suppression in monolithically integrated Michelson interferometer

A novel monolithically integrated Michelson interferometer using intersecting twin-contact semiconductor optical amplifiers is proposed and implemented whereby the two arms are gain imbalanced to give enhanced noise suppression. Experimental OSNR improvements of 8.4 dB for pulses with durations 8 ps and by default ER of 14 dB are demonstrated for low driving currents of between 25 and 30 mA. This is believed to be the smallest Michelson interferometer to date.

Development of low entropy coding in a recurrent network.

In this paper we present an unsupervised neural network which exhibits competition between units via inhibitory feedback. The operation is such as to minimize reconstruction error, both for individual patterns, and over the entire training set. A key difference from networks which perform principal components analysis, or one of its variants, is the ability to converge to non-orthogonal weight values. We discuss the network's operation in relation to the twin goals of maximizing information transfer and minimizing code entropy, and show how the assignment of prior probabilities to network outputs can help to reduce entropy. We present results from two binary coding problems, and from experiments with image coding.

Porphyrin detection in denatured cnidarian tissue extracts

Porphyrin metabolic disruption from exposure to xenobiotic contaminants such as heavy metals, dioxins, and aromatic hydrocarbons can elicit overproduction of porphyrins. Measurement of porphyrin levels, when used in conjunction with other diagnostic assays, can help elucidate an organism’s physiological condition and provide evidence for exposure to certain toxicants. A sensitive microplate fluorometric assay has been optimized for detecting total porphyrin levels in detergent solubilized protein extracts from symbiotic, dinoflagellate containing cnidarian tissues. The denaturing buffer used in this modified assay contains a number of potentially interfering components (e.g., sodium dodecyl sulfate (SDS), dithiothreitol (DTT), protease inhibitors, and chlorophyll from the symbiotic zooxanthellae), which required examination and validation. Examination of buffer components were validated for use in this porphyrin assay; while the use of a specific spectrofluorometric filter (excitation 400 ± 15 nm; emission 600 ± 20 nm) minimized chlorophyll interference. The detection limit for this assay is 10 fmol of total porphyrin per μg of total soluble protein and linearity is maintained up to 5000 fmol. The ability to measure total porphyrins in a SDS protein extract now allows a single extract to be used in multiple assays. This is an advantage over classical methods, particularly when tissue samples are limiting, as is often the case with coral due to availability and collection permit restrictions.

Soil conditioning under London

The CTRL Contract 220 covered 7.5km twin-bore tunnels excavated between late 2002 and early 2004 from Stratford Box to St Pancras station in Central London. To ensure efficient machine operation as well as the transport and disposal of soil, soil conditioning treatments were applied. Specifically, the foam injection ratio (FIR) and the polymer injection ratio (PIR) (injected volume of foam and polymer solution expressed as a percentage of the excavated soil volume) were employed. It was found that carefully selected soil conditioning allowed chamber pressures of 200kPa or more to be accurately controlled in the stiff London Clay and to an extent, in the very stiff clays of the Lambeth Group. Average FIRs of 50% and PIRs of 7 and 9% were used in the Thanet Sand and in the Lambeth Group Clays. In contrast, much lower quantities of foam were used in the London Clay.

Monitoring tunnel deformation induced by close-proximity bored tunneling using distributed optical fiber strain measurements

The paper describes the use of optical fiber Brillouin Optical Time Domain Reflectometry (BOTDR) to monitor the strain distribution in an existing tunnel while a twin tunnel was bored at close-proximity. The twin circular bored tunnels between Serangoon and Bartley stations on the new Circle Line Stage 3 subway in Singapore were constructed at close-proximity to avoid underpinning the foundations of adjacent buildings. The minimum clear separation of the two tunnels is 2.3m (0.4 times the tunnel diameter). The Outer Tunnel was constructed first, followed by the Inner Tunnel, with the earth-pressure balance tunnel boring machines maintained at a minimum of 100m apart. In this trial application of BOTDR, the strain distribution along the Outer Tunnel was measured, in order to monitor its deformation due to the boring of the Inner Tunnel at close-proximity. The aim of the trial application was to determine the practicality of this monitoring method for future use in 'live' tunnels. This paper compares the measurements obtained from optical fiber BOTDR with conventional methods of tunnel monitoring and describes preliminary installation and workmanship guidelines derived from lessons learnt during this trial. © 2007 ASCE.

Preliminary observations in the design and operation of a three panel, double trawl net

Fishing operations were conducted off Kakinada using a 3 panel double trawl net with twin cod-ends to study the utility of the net in catching both bottom and off bottom fishes. The observations indicate that the net is effective in simultaneous catching of bottom as well as off-bottom fishes and separating them while in operation. The design details of the net and the particulars of the fishing operations conducted are presented.

A study of Rastrineobola argentea (Pellegrin), (Pisces : Cyprinidae) and its importance in the fisheries of Lake Kyoga and the northern waters of Lake Victoria

Rastrineobola argentea is the only native fish species which is still abundant in Lakes Victoria and Kyoga, the others being two introduced species; Lates niloticus and Oreochromis niloticus. It forms an important commercial fishery in Lake Victoria and is very important as food of Lates niloticus in both lakes. The depletion of the originally abundant insectivorous and zooplanktivorous hap lochromines due to predation by Lates niloticus appears to have favoured it by reducing potential competitors for food. It now consumes a wide range of invertebrate organisms that originally used to be eaten by different specialised species of haplochromines which include: larvae and pupae of chironomids and chaoborids, copepods and ostracods. Its size in Lake Kyoga (where the Nile perch was introduced earlier) has, however, decreased and is smaller than that in Lake Victoria probably due to high predation pressure. The twin effect of predation and fishing are likely to exert heavy pressure on the species. Research is therefore required to provide information for its management.