Absorption Spectroscopy

Nilapwar, Sanjay; Nardelli, Maria; Westerhoff, Hans V.; Verma, Malkhey

doi:10.1016/b978-0-12-385118-5.00004-9

Cited by 16 publications

(12 citation statements)

References 9 publications

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“…Starch damage was measured using the Megazyme K‐SDAM Total Starch Enzymatic Assay Kit, following AACC Approved Method 76–31.01. A spectrophotometer at 510 nm was used to measure the intensity of light emitted by the sample (Nilapwar et al., 2011). The absorbance value was then used in equation to calculate the percentage of starch damage.

% Starch damage = Δ E \times \frac{normalF}{normalW} \times 8.1

…”

Section: Methodsmentioning

confidence: 99%

Roller milling performance of dry yellow split peas: Mill stream composition and functional characteristics

Price

Kiszonas²,

Smith

et al. 2021

Cereal Chem

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Background and objectives Yellow split pea flour is a growing trend in the food sector as a functional ingredient. The aim here was to analyze the milling performance and composition of dry yellow split peas on a pilot roller mill and determine whether there were differences in pea cotyledon fractionation. Findings Dry yellow split peas were efficiently roller milled with complete recovery in nine mill streams; over half of the flour was produced on two. All streams except 4th Midds had a high proportion of particles <125 μm, starch damage levels similar to wheat flour, and similar protein, pasting, and solvent retention capacities. The 4th Midds represented only 1% of the total flour. Conclusion This study shows that dry yellow split peas can be efficiently milled on a wheat roller mill to a small particle size. In contrast to wheat, split peas are fairly uniform in composition with modest differences among mill streams. Flour recovery was essentially 99%. Significance and novelty To serve as a food ingredient, dry split peas must first be reduced to small particles. Roller milling, though not a traditional method, was shown to be highly efficient. Unlike wheat, pea flour streams were rather similar in composition and functionality.

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% Starch damage = Δ E \times \frac{normalF}{normalW} \times 8.1

…”

Section: Methodsmentioning

confidence: 99%

Roller milling performance of dry yellow split peas: Mill stream composition and functional characteristics

Price

Kiszonas²,

Smith

et al. 2021

Cereal Chem

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“…In contrast, absorbance detection has the potential for smaller and simpler set-ups as well as not requiring a fluorescent label. 13 Absorption spectroscopy is widely used as a readout in colorimetric assays 14 , protein quantification 15 and enzyme kinetics 16 and therefore compliments fluorescent techniques. The standard samples are measured in a cuvette requiring a sample volume of typically 0.2 – 4 mL with 1 cm path lengths 16 .…”

Section: Introductionmentioning

confidence: 99%

Sorting of droplets at kHz rates using absorbance activated acoustic sorting

Richter

Link

McGrath

et al. 2022

Preprint

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Droplet microfluidics allows one to address the ever-increasing demand to screen large libraries of biological samples. Absorbance spectroscopy complements the golden standard of fluorescence detection by label free target identification and providing more quantifiable data. However, this is limited by speed and sensitivity. In this paper we increase the speed of sorting by including acoustofluidics, achieving sorting rates of target droplets of 1 kHz. We improved the devices design for detection of absorbance using fibre-based interrogation of samples with integrated lenses in the microfluidic PDMS device for focusing and collimation of light. This optical improvement reduces the scattering and refraction artefacts, improving the signal quality and sensitivity. The novel design allows us to overcome limitations based on dielectrophoresis sorting, such as droplet size dependency, material and dielectric properties of samples. Our acoustic activated absorbance sorter removes the need for offset dyes or matching oils and sorts about a magnitude faster than current absorbance sorter.

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“…A energia fornecida pela radiação incidente deve permitir que elétrons em um orbital de uma molécula transitem para um orbital de maior energia, uma vez que, a absorção de fótons pelas moléculas numa solução é muito rápida para o calor escapar da molécula absorvente. A diferença de energia entre o estado fundamental e o estado excitado da molécula deve ser precisamente igual à energia do fóton (equação 1)[49]. com diferentes variações de energia[51].…”

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“…Ambas as transições σ → σ * e n → σ * requerem uma energia muito alta e ocorrem na região do ultravioleta distante (150-250 nm). A maioria dos espectros de absorção UV-visíveis envolvem as transições de elétrons n ou π para o orbital π * , sendo estes orbitais envolvidos nas transições[49]. Diagrama representativo das transições eletrônicas.Na qual A é absorbância da amostra, I 0 e I são as intensidades de luz incidente e transmitida, respectivamente.…”

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“…A constante de proporcionalidade ɛ é chamada de coeficiente de absortividade molar, cuja unidadeé L mol -1 cm -1 e é determinado no comprimento de onda máximo de absorção, para um determinado solvente.A espectroscopia de absorção é amplamente utilizada para obter espectros de absorbâncias em função do comprimento de onda de moléculas específicas em solução e em sólidos. Esta técnica tem evoluído como o método preferido para estudos quantitativos e qualitativos, tais como, estimar concentração de proteína em soluções, determinação do coeficiente de absorção molar, estimativa da temperatura de fusão do DNA, determinação do ponto de protonação da molécula (pK), análise de interação biomolecular, cinética enzimática, etc[49,50].3.3.2 FluorescênciaA espectroscopia de fluorescência é uma das técnicas mais utilizadas para o estudo da estrutura e função de macromoléculas em biologia, química, especialmente nas pesquisas de interações de proteínas. A aplicação generalizada de fluorescência no estudo de interações biológicas pode ser explicada por uma combinação de sua alta sensibilidade, facilidade de uso, rapidez, reprodutibilidade e adaptabilidade[52].A absorção pode promover a molécula para um estado de energia maior S 2 , S 3 ,... ou um nível vibracional de maior energia no estado S1 num período de tempo da ordem de 10 -15 As sondas fluorescentes podem ser divididas em três classes: sondas intrínsecas, sondas extrínsecas ligadas covalentemente e sondas extrínsecas associativas.…”

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Estudos espectroscópicos da hemoglobina de >i<Glossoscolex paulistus>/i< (HbGp) modificada pela sonda Fluoresceína isotiocianato e caracterização da apo-HbGp na ausência e presença da sonda 1-Anilino-8-naftaleno-sulfonato (ANS).

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The extracellular hemoglobin of Glossoscolex paulistus (HbGp) has a molecular mass of 3.6 MDa, determined by analytical ultracentrifugation. This protein has an oligomeric structure composed by 144 globin chains, and 36 additional chains lacking the heme group, named linkers. This class of proteins has a high resistance to oxidation and high oligomeric stability when subjected to stressful conditions such as temperature variation, pH and addition of chemical agents (urea, GuHCl, and surfactants). The first part of the results of this work describes the oxy-HbGp oligomeric stability, in the presence of urea, at pH 7.0, monitored by fluorescein isothiocyanate (FITC) fluorescence probe. This study was developed through the use of several spectroscopic techniques, such as, UV-VIS optical absorption, static and timeresolved fluorescence (time-correlated single photon counting TCSPC), static anisotropy and time-resolved anisotropy decay. Fluorescence lifetimes were monitored for both tryptophans and FITC and the corresponding emission decays were obtained. Tryptophan decays are multi-exponential with four characteristic lifetimes: two in the picosecond and two in the nanosecond time ranges. The tryptophan emission decays for pure HbGp and HbGp-FITC systems are quite similar. In the absence of denaturant, and up to 2.5 mol L-1 of urea, the shorter lifetimes predominate in the decay. At 3.5 and 6.0 mol L-1 of urea, the longer lifetimes increase significantly their contribution. Urea-induced unfolding process is characterized by protein oligomeric dissociation and denaturation of dissociated subunits. FITC emission decays for FITC-HbGp system are also multi-exponential with three lifetimes: two in the subnanosecond and one in the nanosecond range with a value quite similar to the free probe in buffer of 3.9 ns. Increase of urea concentration leads to increase of the longer lifetime contribution, implying the removal of the quenching of the probe emission observed for the native HbGp-FITC system. On the other hand, anisotropy decays are characterized by two rotational correlation times associated to the bound probe, and are due to some residual motion of the probe relative to the protein. In the second part of this work the apo-HbGp (oxy-HbGp without heme groups)was studied through a set of techniques: Sodium dodecyl sulfate-Polyacrylamide Gel Electrophoresis (SDS-PAGE), Analytical Ultracentrifugation (AUC), Dynamic Light Scattering (DLS), UV-VIS optical absorption, Circular Dichroism (CD), static and time-resolved fluorescence, in the absence and in the presence of 8-anilino-1naphtalene-sulfonic acid (ANS) probe. Moreover, the apo-HbGp concentration was

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Absorption Spectroscopy

Cited by 16 publications

References 9 publications

Roller milling performance of dry yellow split peas: Mill stream composition and functional characteristics

Roller milling performance of dry yellow split peas: Mill stream composition and functional characteristics

Sorting of droplets at kHz rates using absorbance activated acoustic sorting

Estudos espectroscópicos da hemoglobina de >i<Glossoscolex paulistus>/i< (HbGp) modificada pela sonda Fluoresceína isotiocianato e caracterização da apo-HbGp na ausência e presença da sonda 1-Anilino-8-naftaleno-sulfonato (ANS).

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