Zn[Formula: see text]Ni[Formula: see text]Te semiconductor nanocrystals in transparent glass for optoelectronic device applications.

Doping glass with semiconductors, particularly with nanostructured semiconductors, has attracted attention due to the large optical absorption cross-sections of the latter. Based on this property, Ni[Formula: see text] (5 wt%) doped phosphate glass and Zn[Formula: see text]Ni[Formula: see text]Te (x = 0.5, 1.0, 5.0 and 10.0 wt% of Ni[Formula: see text]) nanocrystals (NCs) doped phosphate glasses (GCs) were prepared by fusion method and subsequent heat treatment. Influence of Ni[Formula: see text] on structural, thermo-optical and third-order nonlinear optical properties have been analysed through various spectroscopic characterizations. The XRD pattern of the glass (G) exhibits the amorphous nature of the host material while GCs exhibit not only amorphous halo but also the presence of quantum dots (QDs) or nanocrystals (NCs) phases. TEM analysis of the studied GCs samples confirm the presence of quantum dots (QDs) and bulk NCs with an average diameter of approximately 4.2 [Formula: see text] 0.3 nm and 13.4 [Formula: see text] 0.2 nm, respectively. Several phosphate groups were observed and reported from Raman and FTIR-ATR spectra. The absorption band positions confirmed that Ni[Formula: see text] ions resemble to the octahedral symmetry. The intensity of absorption band around 1352 nm ([Formula: see text]T[Formula: see text](F) [Formula: see text] [Formula: see text]A[Formula: see text](F)) increased with the increase of Ni[Formula: see text] in GCs which is an indicative of the [Formula: see text]Ni[Formula: see text] coordination. The emission properties such as emission cross-sections ([Formula: see text]) full width at half maxima (FWHM) for the [Formula: see text]T[Formula: see text](D) [Formula: see text] [Formula: see text]T[Formula: see text](F) (visible) and [Formula: see text]A[Formula: see text](F) [Formula: see text] [Formula: see text]T[Formula: see text](F) (near-infrared) emission transitions were reported. Among the glass-containing semiconductor nanocrystals (GCs), the emission cross-sections in GC4 sample (x = 10% of Ni[Formula: see text]) are the largest for both the visible (11.88 [Formula: see text] 10[Formula: see text] cm[Formula: see text]) and infrared (0.98 [Formula: see text] 10[Formula: see text] cm[Formula: see text]) transitions. Thermal diffusivity (D), thermal conductivity (K) and temperature dependent optical path length change (ds/dT) were obtained through time-resolved thermal lens (TL) and thermal relaxation (TR) methods. The D and K parameters do not change significantly with increase of Ni[Formula: see text] ions (0.5-5%) in GCs. Nonlinear-refractive index and nonlinear absorption of the studied samples were also obtained using femtosecond Z-scan technique. The increase of nonlinear absorption coefficient ([Formula: see text]) is observed from GC2 (2.53 [Formula: see text] 10[Formula: see text] cm/W) to GC4 (7.98 [Formula: see text] 10[Formula: see text] cm/W). The GC4, sample with 10 wt% of Ni[Formula: see text], showed the lowest ds/dT (1.22 [Formula: see text] 10[Formula: see text] K[Formula: see text]) with good lasing (FOM and emission cross-sections) and nonlinear absorption properties suggesting that it can be a good candidate for visible-red emission light conversion in LED technology.

Near-infrared quantum cutting luminescence in Pr3+/Yb3+ doped lead bismuth borate glass.

In this paper, thermally stable lead-bismuth-borate glasses were doped with 0.5 mol% of Pr3+ ions at several concentration levels of Yb3+ ions. Structural characterizations were performed via Raman, differential scanning calorimetry, optical absorption and fluorescence spectra. The Judd-Ofelt intensity parameter, [Formula: see text], of Pr3+ doped glass was comparatively higher than those from reported ones, which reflects the increase of co-valency and asymmetry of chemical bonds in the local environment of Pr3+. Near-infrared emission in 900-2200 nm wavelength range was recorded through 443 nm blue laser pumping. Visible to near-IR quantum cutting and concentration quenching mechanisms were discussed to understand the luminescent behaviour. Intense IR emission ([Formula: see text] features generated by absorbing one visible photon leads to quantum efficiencies close to 128% in Pr3+/Yb3+ co-doped samples which may improve the solar spectrum absorption and accordingly, increase the efficiency of c-Si solar cells. Emission cross-section, lifetime, figure of merit and gain bandwidth corresponding to Pr3+: [Formula: see text] ([Formula: see text]m) were comparatively reported suggesting that the glass with molar composition 0.5Pr3+/0.1Yb3+ might be a potential candidate for [Formula: see text]m laser operation with low pump threshold.

Origin geographical classification of green coffee beans (Coffea a rabica L.) produced in different regions of the Minas Gerais state by FT-MIR and chemometric.

The present work was proposal the potential evaluation of Fourier-Transform Mid-Infrared (FT-MIR) associated with chemometric approach in green beans, in order to discriminate the origin of special Arabica coffees in a single state that has heterogeneous environments. Partial Least Squares Discriminant Analysis (PLS-DA) model presented as result: 3 latent variables, R 2 X (cum) = 0.892, R 2 Y (cum) = 0.659; Q 2 Y (cum) = 0.494, RMSEP = 0.182387, p-value CV-Anova = 0.009, 100% of both sensitivity and specificity and the prediction classification obtained was: 100, 83.33, 100, 83.33% for class 1, class 2, class 3 and class 4, respectively. These results can be considered adequate for the proposed hypothesis. The obtained results that the regions have markers such as trigonelline, chlorogenic and fatty acids, sensitive to absorption in the mid-infrared and that are able to determine the origin of green coffee beans of Arabica. Thus, the FT-MIR associated with chemometrics has the potential to employ speed, modernity and cost reduction in the certification of origin of coffees.

FT-NIR associado a método quimiométrico para discriminar resíduos de antimicrobianos e antiparasitário no leite / FT-NIR coupled to chemometric method to discriminate antimicrobial and antiparasitic residues in milk

Introdução: O leite é um dos alimentos mais consumidos pelos seres humanos. Proteínas, vitaminas, gordura, carboidratos e sais minerais fazem parte de sua composição e desempenham importantes funções para a nutrição humana. A prática de adulteração no leite é antiga e ainda se faz presente nos dias de hoje em diversos países, inclusive no Brasil. A fim de obter lucro maior, alguns fornecedores costumam adicionar ao leite: água, amido, citrato, ureia, soda cáustica, cloreto de sódio, sacarose, soro do leite, melamina e outros componentes. No entanto, ainda há outro problema, o da contaminação do leite por medicamentos veterinários. Estes podem causar danos à saúde do consumidor e prejuízos para a produção de seus derivados. Objetivo: O presente trabalho propõe uma metodologia que permite detectar de maneira rápida a presença de resíduos de medicamentos veterinários em leites, dentro do limite máximo de resíduos de cada droga. Métodos: Fez-se o uso da espectroscopia no infravermelho próximo por transformada de Fourier associada à análise de componentes principais. A espectroscopia no infravermelho tem sido utilizada não somente para a autenticidade de laticínios, mas para determinar sua qualidade. Resultados: Conseguiu-se detectar resíduos de penicilina, oxitetraciclina e enrofloxacino, e também do antiparasitário ivermectina nas amostras de leites. Conclusão: A metodologia detectou de maneira rápida e precisa os resíduos das drogas analisadas, mesmo em concentrações muito baixas. Assim, é uma opção a outras existentes, já utilizadas para tal objetivo. (AU)

Introduction: Milk is one of the most consumed foods by humans. Proteins, vitamins, fat, carbohydrates and minerals are part of its composition and play important roles in human nutrition. The practice of adulteration in milk is old and is still present today in several countries, including Brazil. In order to obtain a higher profit, some suppliers usually add to the milk: water, starch, citrate, urea, caustic soda, sodium chloride, sucrose, whey, melamine and other components. However, there is still another problem, that of contamination of milk by veterinary medicines. These can cause damage to the health of the consumer and damage to the production of its derivatives. Objective: The present work proposes a methodology that allows to quickly detect the presence of residues of veterinary medicines in milk, within the maximum residue limit of each drug. Methods: The use of spectroscopy in the near infrared by Fourier transform associated with the analysis of principal components was used. Infrared spectroscopy has been used not only for the authenticity of dairy products, but to determine their quality. Results: It was possible to detect residues of penicillin, oxytetracycline and enrofloxacin, and also of the antiparasitic ivermectin in the milk samples. Conclusion: The methodology fastly and accurately detected the residues of the analyzed drugs, even in very low concentrations. Thus, it is an option to other existing ones, already used for this purpose. (AU)

Comparative data on effects of alkaline pretreatments and enzymatic hydrolysis on bioemulsifier production from sugarcane straw by Cutaneotrichosporon mucoides.

Bioemulsifiers are surface active compounds which could be potentially used in food processing, cosmetic sector and oil recovery. Sugarcane straw (SS), was used as the raw substrate for the production of bio-emulsifiers (BE) by Cutaneotrichosporon mucoides. Three different delignification strategies using dilute sodium hydroxide, sodium sulfite and ammonium hydroxide followed by enzymatic hydrolysis (Cellic CTec 2, 7.5% total solids, 15 FPU/g, 72 h) were studied. Enzyme hydrolysis of ammonium hydroxide pretreated SS showed a maximum of 62.19 ± 0.74 g/l total reducing sugars with 88.35% hydrolytic efficiency (HE) followed by sodium hydroxide (60.06 ± 0.33 g/l; 85.40% HE) and sodium sulfite pretreated SS (57.22 ± 0.52 g/l; 84.71% HE), respectively. The ultrastructure of SS (native and delignified) by fourier transform-infrared and near infrared spectroscopy, revealed notable structural differences. The fermentation of hydrolysates by C. mucoides into bioemulsifiers showing emulsification index (EI) of 54.33%, 48.66% and 32.66% from sodium sulfite, sodium hydroxide, and ammonium hydroxide pretreated SS, respectively.

Evaluation of the effects of mild heat in bovine milk by time resolved fluorescence.

Heat treatment of milk and dairy products are indispensable for the dairy industry. This thermal processing intends to extend shelf life, improve quality of the milk and minimize the health risks associated with milk and dairy products. The use of time-resolved fluorescence techniques to identify conformation and structure changes ok milk fat and proteins could help understand the temperature effects in bovine milk. This study aimed to use fluorescence lifetimes to evaluate the effects of heating fresh cow milk up to 85 °C. We observed different tendencies for fluorescence lifetimes submitted to different heating temperatures. The longer lifetime values decreased for temperatures higher than room temperature until it reached a minimum value near 40 °C and it slowly increased again for temperatures higher than 40 °C, indicating two distinct processes. These results indicate that time-resolved fluorescence can assist on the analysis of heating effects in fluid milk.

Results from portable and of low cost equipment developed for detection of milk adulterations

Abstract This work presents the results of a device, MilkTech, developed to detect milk tampering, based on electrical measurements. The device indicates possible frauds by water, sodium chloride, caustic soda, ethyl alcohol and sodium bicarbonate. The advantages in relation to traditional methods are portability, low cost and detection of mixed frauds. The experiments were conducted in dairy plants at Governador Valadares, in Brazil. The results were compared with cryoscopy and chloride tests. It is demonstrated there is high correlation between MilkTech and Cryoscopy. For instance, the detection limit of the equipment for water addition with the set of analyzed data was 0.78% with precision of 1.1%. Adulterations with sodium chloride, caustic soda, ethyl alcohol and sodium bicarbonate are detected qualitatively, even when added with water, and MilkTech indicates "SUSPECT" milk.

Time resolved fluorescence of cow and goat milk powder.

Milk powder is an international dairy commodity. Goat and cow milk powders are significant sources of nutrients and the investigation of the authenticity and classification of milk powder is particularly important. The use of time-resolved fluorescence techniques to distinguish chemical composition and structure modifications could assist develop a portable and non-destructive methodology to perform milk powder classification and determine composition. This study goal is to differentiate milk powder samples from cows and goats using fluorescence lifetimes. The samples were excited at 315nm and the fluorescence intensity decay registered at 468nm. We observed fluorescence lifetimes of 1.5±0.3, 6.4±0.4 and 18.7±2.5ns for goat milk powder; and 1.7±0.3, 6.9±0.2 and 29.9±1.6ns for cow's milk powder. We discriminate goat and cow powder milk by analysis of variance using Fisher's method. In addition, we employed quadratic discriminant analysis to differentiate the milk samples with accuracy of 100%. Our results suggest that time-resolved fluorescence can provide a new method to the analysis of powder milk and its composition.

Quantification of whey in fluid milk using confocal Raman microscopy and artificial neural network.

In this work, we assessed the use of confocal Raman microscopy and artificial neural network as a practical method to assess and quantify adulteration of fluid milk by addition of whey. Milk samples with added whey (from 0 to 100%) were prepared, simulating different levels of fraudulent adulteration. All analyses were carried out by direct inspection at the light microscope after depositing drops from each sample on a microscope slide and drying them at room temperature. No pre- or posttreatment (e.g., sample preparation or spectral correction) was required in the analyses. Quantitative determination of adulteration was performed through a feed-forward artificial neural network (ANN). Different ANN configurations were evaluated based on their coefficient of determination (R2) and root mean square error values, which were criteria for selecting the best predictor model. In the selected model, we observed that data from both training and validation subsets presented R2>99.99%, indicating that the combination of confocal Raman microscopy and ANN is a rapid, simple, and efficient method to quantify milk adulteration by whey. Because sample preparation and postprocessing of spectra were not required, the method has potential applications in health surveillance and food quality monitoring.

Multi-scale structural and chemical analysis of sugarcane bagasse in the process of sequential acid-base pretreatment and ethanol production by Scheffersomyces shehatae and Saccharomyces cerevisiae.

BACKGROUND: Heavy usage of gasoline, burgeoning fuel prices, and environmental issues have paved the way for the exploration of cellulosic ethanol. Cellulosic ethanol production technologies are emerging and require continued technological advancements. One of the most challenging issues is the pretreatment of lignocellulosic biomass for the desired sugars yields after enzymatic hydrolysis. We hypothesized that consecutive dilute sulfuric acid-dilute sodium hydroxide pretreatment would overcome the native recalcitrance of sugarcane bagasse (SB) by enhancing cellulase accessibility of the embedded cellulosic microfibrils. RESULTS: SB hemicellulosic hydrolysate after concentration by vacuum evaporation and detoxification showed 30.89 g/l xylose along with other products (0.32 g/l glucose, 2.31 g/l arabinose, and 1.26 g/l acetic acid). The recovered cellulignin was subsequently delignified by sodium hydroxide mediated pretreatment. The acid-base pretreated material released 48.50 g/l total reducing sugars (0.91 g sugars/g cellulose amount in SB) after enzymatic hydrolysis. Ultra-structural mapping of acid-base pretreated and enzyme hydrolyzed SB by microscopic analysis (scanning electron microcopy (SEM), transmitted light microscopy (TLM), and spectroscopic analysis (X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Fourier transform near-infrared (FT-NIR) spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy) elucidated the molecular changes in hemicellulose, cellulose, and lignin components of bagasse. The detoxified hemicellulosic hydrolysate was fermented by Scheffersomyces shehatae (syn. Candida shehatae UFMG HM 52.2) and resulted in 9.11 g/l ethanol production (yield 0.38 g/g) after 48 hours of fermentation. Enzymatic hydrolysate when fermented by Saccharomyces cerevisiae 174 revealed 8.13 g/l ethanol (yield 0.22 g/g) after 72 hours of fermentation. CONCLUSIONS: Multi-scale structural studies of SB after sequential acid-base pretreatment and enzymatic hydrolysis showed marked changes in hemicellulose and lignin removal at molecular level. The cellulosic material showed high saccharification efficiency after enzymatic hydrolysis. Hemicellulosic and cellulosic hydrolysates revealed moderate ethanol production by S. shehatae and S. cerevisiae under batch fermentation conditions.

Análise de Resíduos de Diclofenaco Sódico Veterinário em Leite por Espectroscopia no Infravermelho Próximo / Analisys Of Residues Of Veterinary Sodium Diclofenac in Milk through Near Infrared Spectroscopy

O leite é um dos alimentos mais consumidos no mundo,principalmente por crianças e idosos. Em 2007, a Polícia Federal realizou uma operação que apontou um gigantesco esquema de fraudes em leites comercializados no Brasil, constatou-se ainda que 1/3 do leite consumido no Brasil não passava por fiscalização. Muitas são as adulterações: adição de água, soda cáustica, cloreto de sódio, entre outros. No entanto, ainda há outro problema, o da contaminação por fármacos veterinários. Estes podem estar presentes em altas concentrações no leite caso este tenha sido ordenhado dentro do período de carência da vaca. O leite contaminado pode causar sérios dados à saúde do consumidor ou então causar prejuízos para a produção de seus derivados. Objetivo: Desenvolver uma técnica complementar para detectar a presença de resíduos de medicamentosveterinários em amostras de leites. Material e Métodos: Atualmente,com o desenvolvimento tecnológico há muitas técnicas de análisemultielementar que permitem estudar os componentes químicos dedeterminadas amostras. O presente trabalho utiliza a técnica deEspectroscopia no Infravermelho Próximo por Transformada de FourierFT-NIR e a Análise de Componentes Principais PCA para detectar apresença de resíduos do medicamento veterinário em leites. Paraisto, simulou-se adulteração do leite com percentuais de (0,1; 0,5 e10)% de fármaco no leite. Resultados: Crioscopia: 0,539 ºH com0,18% de água; leite não ácido pelo teste do Alizarol; pH 6,71; Gordura:3,25%; Proteína: 3,01%; Lactose: 4,55%; Sólidos: 10,80%. Resíduosdo fármaco foram observados via derivada primeira de espectros derefletância, e análise de PCA em níveis inferiores a 1%. Conclusão:o sistema FT-NIR pôde detectar os resíduos dos fármacos estudadosdentro dos percentuais simulados...

Milk is one of most consumed food by human beings,especially children and elderly. In 2007, the Federal Police conductedan operation that showed an enormous fraud scheme in industrializedmilk in Brazil. In addition, they found out that 1/3 of the milk consumedin Brazil did not pass by inspection. There are several ways to adulteratemilk, such as with addition of water, caustic soda, sodium chlorideand others. However, there is another issue, that is, milk contaminationwith veterinary drugs. These drugs may be present in highconcentrations in milk, in case the cow was milked in the clearanceperiod. Contaminated milk can cause damages to consumers’ healthor injury to the production of derivates. Objective: To develop acomplementary technique to detect the presence of residues ofveterinary drugs in milk samples. Material and Methods: currently,given the technological development, there are many techniquesbased on multielement analysis for studying the chemical componentsof different samples. This paper uses the technique of FourierTransform Near Infrared Spectroscopy and the Principal ComponentsAnalysis (PCA) to detect the evidence of residues of veterinarydrugs in milk. To this end, we simulated adulteration in milk withpercentages of 0.1%, 0.5% and 10% drugs in milk. Results: cryoscopy:0.539 ºH with 0.18% water; non-acid milk according to Alizarol test; pH6.71; Fat: 3.25%; Protein: 3.01%; Lactose: 4.55%; Solids: 10.80%.Drug residues were observed via the first derivative of reflectancespectra and PCA analysis at levels below 1%. Conclusion: The resultwas positive indicating that the FT-NIR system can detected theresidues of studied drugs within the simulated percentage...

Ultra-structural mapping of sugarcane bagasse after oxalic acid fiber expansion (OAFEX) and ethanol production by Candida shehatae and Saccharomyces cerevisiae.

BACKGROUND: Diminishing supplies of fossil fuels and oil spills are rousing to explore the alternative sources of energy that can be produced from non-food/feed-based substrates. Due to its abundance, sugarcane bagasse (SB) could be a model substrate for the second-generation biofuel cellulosic ethanol. However, the efficient bioconversion of SB remains a challenge for the commercial production of cellulosic ethanol. We hypothesized that oxalic-acid-mediated thermochemical pretreatment (OAFEX) would overcome the native recalcitrance of SB by enhancing the cellulase amenability toward the embedded cellulosic microfibrils. RESULTS: OAFEX treatment revealed the solubilization of hemicellulose releasing sugars (12.56 g/l xylose and 1.85 g/l glucose), leaving cellulignin in an accessible form for enzymatic hydrolysis. The highest hydrolytic efficiency (66.51%) of cellulignin was achieved by enzymatic hydrolysis (Celluclast 1.5 L and Novozym 188). The ultrastructure characterization of SB using scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy, Fourier transform-near infrared spectroscopy (FT-NIR), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) revealed structural differences before and after OAFEX treatment with enzymatic hydrolysis. Furthermore, fermentation mediated by C. shehatae UFMG HM52.2 and S. cerevisiae 174 showed fuel ethanol production from detoxified acid (3.2 g/l, yield 0.353 g/g; 0.52 g/l, yield, 0.246 g/g) and enzymatic hydrolysates (4.83 g/l, yield, 0.28 g/g; 6.6 g/l, yield 0.46 g/g). CONCLUSIONS: OAFEX treatment revealed marked hemicellulose degradation, improving the cellulases' ability to access the cellulignin and release fermentable sugars from the pretreated substrate. The ultrastructure of SB after OAFEX and enzymatic hydrolysis of cellulignin established thorough insights at the molecular level.