170,302 research outputs found
PENGARUH PENAMBAHAN ENZIM TANASE TERHADAP SIFAT KIMIA SIRUP BUAH SEMU JAMBU METE (ANACARDIUM OCCIDENTALE LINN)
No full textAbstrak: Sebelumnya telah dihasilkan enzim tanase dari Aspergillus niger menggunakan media padat.Pada penelitian ini, enzim tanase yang dihasilkan diaplikasikan pada sirup buah jambu mete.ÃÂ Penelitian ini bertujuan untuk mengetahui pengaruh penambahan enzim tanase terhadap sifat sirup buah jambu. Konsentrasi enzim yang digunakan divariasi 0%; 0,02%; 0,04%; 0,06%; 0,08% dan 0,1%. Hasil yang diperoleh dibandingkan dengan sifat kimia sirup buah jambu mete yang diberi perlakuan dengan suhu tinggi (100oC). Hasil penelitian menunjukkan bahwa penambahan enzim tanase sebesar 0,1% memberikan hasil yang paling baik untuk menurunkan kandungan tannin jika dibandingkan dengan penggunaan suhu tinggi. Kadar glukosa mengalami peningkatan yang signifikan untuk sirup yang diberi perlakuan dengan suhu tinggi. Hasil analisis vitamin C, protein dan pH tidak mengalami perubahan pada sirup buah jambu mete yang diberi perlakuan dengan enzim tanase. Penggunaan suhu tinggi menyebabkan penurunan kadar vitamin C dan protein secara signifikan.Kata Kunci : Buah Semu Jambu Mete, Enzim Tanase, TaninÃÂ Abstract: We previously produced tannase from Aspergillus niger using solid state medium. In the present study the enzyme usedÃÂ cashew apple juice. The aim this research was to know effect of tannase on chemical parameters of cashew apple juice. The concentration of tannase used was 0%;0.02%; 0.04%; 0.06%; 0.08% and 0.1% (v/v) and this result compared with high temperature treatment (100 oC). Cashew apple juice with tannase treatment resulted in reduced of tannin and increased of glucose and the best result was obtained at the concentration tannase 0,01% (v/v). Tannase treatment not affect ascorbic acid, pH, and protein but high temperature treatment can reduce ascorbic acid content and protein.Key words: cashew apple juice, tannase, tannin</jats:p
Unified charge transport in disordered organic field-effect transistors and light-emitting diodes
No full textDe ontdekking dat plastics zich als halfgeleiders kunnen gedragen heeft hun toepassingsgebied verruimd van speelgoed, tassen of meubilair naar elektronische producten zoals flexibele beeldschermen, radiofrequentie identificatie labels, fotocellen and chemische sensoren. In dit proefschrift
bestuderen we de geleiding in wanorderlijke organische halfgeleiders. Deze materialen zijn bestudeerd onder de omstandigheden zoals ze in licht emitterende diodes (LEDs) en veldeffect transistoren (FETs) gebruikt worden.
Een belangrijke parameter voor de beschrijving van de prestatie van deze applicaties is de mobiliteit van de ladingsdragers, hetgeen een maat is voor de snelheid waarmee de ladingsdragers door de polymeerfilm bewegen. Wij
analyseren de mobiliteit van ladingsdragers als functie van temperatuur, elektrisch veld en ladingsdragerdichtheid. We laten zien dat een geunificeerd model voor zowel LEDs als FETs gebruikt kan worden, waarin de afhankelijkheid van de mobiliteit van de ladingsdragerdichtheid wordt meegenomen. Deze resultaten worden vervolgens gebruikt om de oorzaak van de sterke toename van de ruimteladingsbegrensde gatenstroom in poly(pphenylene vinylene) (PPV)-achtige polymeren bij hoge aangelegde spanningen te onderzoeken. We tonen aan dat de toename van de stroomdichtheid in ruimteladingsbegrensde diodes bij kamertemperatuur
gedomineerd wordt door de dichtheidsafhankelijkheid van de gatenmobiliteit. Dit is in tegenspraak met de in de literatuur algemeen geaccepteerde aanname dat de bijdrage van het elektrische veld overheerst.
Het ladingstransport van verschillende PPV derivaten zijn bestudeerd als functie van de chemische structuur en proces condities. Er wordt aangetoond dat d.m.v. chemische modificatie van asymmetrische naar volledig symmetrische gesubstitueerde PPVs de mobiliteit significant verbeterd kan
worden.
Een nieuw concept voor efficiente dubbellaag polymeren LEDs wordt gedemonstreerd. Een dergelijke LED bevat een polymeer met een hoge gatenmobiliteit, die de gaten efficient naar een sterk luminescerende laag transporteert.
On estimating the conditional expected shortfall
No full textUnlike the value at risk, the expected shortfall is a coherent measure of risk. In this paper, we discuss estimation of the expected shortfall of a random variable Y-t with special reference to the case when auxiliary information is available in the form of a set of predictors X-t. We consider three classes of estimators of the conditional expected shortfall of Y-t given X-t: a class of fully non-parametric estimators and two classes of analog estimators based, respectively, on the empirical conditional quantile function and the empirical conditional distribution function. We study their sampling properties by means of a set of Monte Carlo experiments and analyze their performance in an empirical application to financial data. Copyright (C) 2008 John Wiley & Sons, Ltd
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Mitomycin C in highly myopic eyes - Author reply
No full textOphthalmology. 2005 Feb;112(2):208-18; discussion 219.
Mitomycin C modulation of corneal wound healing after photorefractive keratectomy in highly myopic eyes.
Gambato C, Ghirlando A, Moretto E, Busato F, Midena E.
SourceRefractive Surgery Service and Antimetabolite Therapy Research Unit, Department of Ophthalmology, University of Padova, Padova, Italy.
Abstract
PURPOSE: To evaluate the role of topical mitomycin C in corneal wound healing (CWH) after photorefractive keratectomy (PRK) in highly myopic eyes.
DESIGN: Prospective, double-masked, randomized clinical trial.
PARTICIPANTS: Seventy-two eyes of 36 patients affected by high (>7 diopters) myopia.
METHODS: In each patient, one eye was randomly assigned to PRK with intraoperative topical 0.02% mitomycin C application, and the fellow eye was treated with a placebo. Postoperatively, mitomycin C-treated eyes received artificial tears (3 times daily, tapered in 3 months), whereas the fellow eye was treated with fluorometholone sodium 2% and artificial tears (3 times daily, tapered in 3 months).
MAIN OUTCOME MEASURES: Uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA), contrast sensitivity, manifest refraction, and biomicroscopy. Contrast sensitivity was determined using the Pelli-Robson chart. Corneal confocal microscopy documented CWH.
RESULTS: Mean follow-up was 18 months (range, 12-36). No side effects or toxic effects were documented. At 12-month follow-up examination, UCVAs (logarithm of the minimum angle of resolution) were 0.4+/-0.48 and 0.5+/-0.53 (P = .03) in mitomycin C-treated eyes and corticosteroid-treated eyes, respectively. At 1 year, corneal haze developed in 20% of corticosteroid-treated eyes, versus 0% of mitomycin C-treated eyes. At 12, 24, and 36 months, corneal confocal microscopy showed activated keratocytes and extracellular matrix significantly more evident in untreated eyes (Ps = 0.004, 0.024, and 0.046, respectively).
CONCLUSION: Topical intraoperative application of 0.02% mitomycin C can reduce haze formation in highly myopic eyes undergoing PRK.
Comment in
Ophthalmology. 2006 Feb;113(2):357; author reply 357-8
Produção, purificação, caracterização e aplicação de tanase de Aspergillus melleus URM 5827 produzida por fermentação em estado sólido utilizando sementes de achachairú (Garcinia humilis (Vahl) C. D. Adam)
No full textTanino acil hidrolase (TAH) conhecida como tanase (E.C:3.1.1.20) é uma enzima que hidrolisa ésteres e ligações laterais de taninos hidrolisáveis. O ácido tânico é um típico tanino hidrolisável, que pode ser hidrolisado por tanase em glicose e ácido gálico. A tanase pode ser obtida a partir de fontes vegetais, animais e microbianas, sendo o meio microbiológico a fonte mais importante de obtenção desta enzima. O chá verde apresenta várias substâncias, dentre elas, as catequinas que são uma importante fonte de antioxidante, que ajudam na manutenção do organismo.A atividade e a purificação de tanase produzida por Aspergillus melleus URM 5827 foi avaliada por fermentação em estado sólido utilizando como substrato sementes de achachairú (Garcinia humilis (Vahl) C. D. Adam). Foram utilizadas 42 culturas de fungos do gênero Aspergillus para seleção qualitativa das culturas com potencial para produção da tanase. Com a cultura selecionada foi realizada uma fermentação em estado sólido utilizando sementes de achachairú como substrato. Um planejamento fatorial (23) foi utilizado para analisar a influência das variáveis de produção: quantidade de substrato, umidade inicial e quantidade de ácido tânico sobre a atividade da tanase. A purificação foi avaliada por cromatografia de troca iônica em DEAE- Sephadex. A máxima atividade foi produzida por Aspergillus melleus URM 5827 com 452,55 unidades por grama de substrato na
base seca (U/gss) utilizando 5,0 g de substrato, com umidade inicial de 60% e 2,0% de ácido tânico em 48 horas de fermentação. A enzima purificada apresentou peso molecular de 69,52 kDa em Superdex G-75, enquanto que em eletroforese SDS-PAGE apresentou 66,5 kDa. Quanto a caracterização, apresentou pH e temperatura ótima de 5,5 e 40ºC respectivamente, obtendo termoestabilidade a 30ºC. A atividade enzimática na presença de íons, surfactantes e inibidores de protease, foi inibida na presença dos íons ZnCl2, ZnSO4 e dos surfactantes triton X-100, SDS, reduzida com os íons CaCl2, KCl, NaCl, MgSO4, CuSO4, dos surfactantes Tween 20, Tween 80 e dos inibidores de protease EDTA e β-mercaptoetanol. A tanase aumentou a atividade antioxidante do chá verde significativamente. Os resultados obtidos no presente estudo, mostram o potencial promissor da tanase produzida por Aspergillus melleus URM 5827 e na sua utilização no aumento do potencial antioxidante do chá verde.Tannin acylhydrolase (TAH) known as tannase (E.C:3.1.1.20) is an enzyme which
hydrolizes esters and lateral bonds of hydrolizable tannins. The tannic acid is a typical
hydrolizable tannin, which can be hydrolized by tannase along with glucose and gallic
acid. Tannase can be obtained from vegetables, animal and microbial sources. From
those, the last is the most important source to obtain the enzyme. Green tea has several
substances, among which catechins are a major source of antioxidant, which help in
maintaining the organism.The activity and purification of tannase produced by
Aspergillus melleus URM 5827 was evaluated by semi solid fermentation using seeds of
mangosteen (Garcinia humilis (Vahl) C. D. Adam) as substract. Forty two cultures
fungical cultures of Aspergillus were used for qualitative selection purposes in order to
verify potential for tannase production. After selecting cultures, it was performed a semi
solid fermentation using seeds of mangosteen as substrate. A factorial planning (2³) was
used to verify the influence of production variables such as: quantity of substrate; initial
moisture and amount of tannic acid over tannase activity. The purification was evaluated
by ionic change chromatography at DEAE-Sephadex. Maximum activity was produced
by Aspergillus melleus URM 5827 with 452.55 units per gram of dry-based substract
(U/gss) using 5.0 grams of substrate, with initial moisture of 60% and 2% of tannic acid
through 48 hours fermentation. The purified enzyme has a molecular weight of 69.52
kDa on Superdex G-75, while on SDS-PAGE electrophoresis showed 66.5 kDa. As for
the characterization, the optimum pH and temperature was 5.5 and 40ºC, respectively,
achieving thermostability at 30ºC. Coughing increases the antioxidant activity of green
tea significantly. The results obtained in this study show the promising potential of
tannase produced by Aspergillus melleus URM 5827 and its use in improving the
antioxidant potential of green tea
Seleção e avaliação da produção de tanase por fungos filamentosos em fermentação submersa utilizando resíduos agrícolas / Selection and evaluation of tannase production by filamentous fungi in submerged fermentation using agricultural residues
No full textTaninos são polifenóis solúveis em água, provenientes do metabolismo secundário das plantas. São classificados em condensados e hidrolisáveis, sendo que esses últimos podem ser convertidos em ácido gálico e glicose pela ação da enzima tanase que atua nas ligações ésteres e laterais de suas moléculas. A enzima tanase é produzida na presença do indutor ácido tânico, ainda pouco explorada devido ao alto custo de sua produção. Assim, é interessante a seleção de microrganismos que produzam grande quantidade desta enzima, bem como o emprego de substratos de baixo custo para sua produção. Portanto, o objetivo do presente estudo foi isolar e selecionar fungos filamentosos presentes na planta da bananeira (Musa sp.) quanto a sua capacidade de produzir tanase e avaliar a produção desta enzima em diferentes condições de cultivo. Foram isolados 40 fungos, entre os quais 8 se destacaram para produção de tanase em meio sólido contendo ácido tânico como única fonte de carbono. Estes foram avaliados em fermentação submersa, na qual o isolado Aspergillus sp. PS2.02 se destacou com uma atividade de 13,20 ± 1,61 U/mL. Após testes de otimização utilizando resíduos agroindustriais, sais, ácido tânico, temperatura e tempo de produção, a atividade máxima encontrada foi de 20,43 ± 0,43 U/mL, em meio contendo casca de banana e 3% de ácido tânico no período de 5 dias de fermentação à 30 ?C. Os resultados se mostram promissores, uma vez que o isolado Aspergillus sp. PS2.02 apresentou uma alta produção de tanase em meio contendo apenas o indutor da enzima, água e casca de banana, um resíduo agrícola amplamente disponível que pode ser utilizado para diminuir os custos da produção desta enzima
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Construction of 3d-4f heterometallic coordination polymers by simultaneous use of hexacyanometalate building-blocks and exo-bidentate ligands
No full textTanase S, Andruh M, Müller A, Schmidtmann M, Mathoniere C, Rombaut G. Construction of 3d-4f heterometallic coordination polymers by simultaneous use of hexacyanometalate building-blocks and exo-bidentate ligands. CHEMICAL COMMUNICATIONS. 2001;(12):1084-1085.The reaction of Pr(NO3)(3) 6H(2)O with 4,4'-bipyridine N,N'-dioxide (L) and K-3[M(CN)(6)] [M Fe-III, Co-III] gives isomorphous heteropolynuclear complexes with formula [{(H2O)(5)LPr-NC-M(CN)(5)}(mu -L)].0.5L.4H(2)O, which exhibit a novel supramolecular architecture created by the interplay of coordinative, hydrogen bonding and pi-pi stacking interactions
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