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1.
J Chromatogr A ; 1626: 461328, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797818

RESUMO

Ferric oxide/carbon (Fe2O3@C) was fabricated via direct carbonization of metal-organic framework of iron (MOF-235) under argon atmosphere. The magnetic Fe2O3 nanoparticles are evenly embedded in porous carbon matrix, while original morphology of MOF-235 was well-maintained. The synthesized Fe2O3@C was used as magnetic sorbent for extracting five benzoylurea insecticides (BUs). The materials exhibited excellent extraction performance, which benefited not only from the strong π-π interaction and hydrophobic interaction (π-conjugated system), but also to the abundant adsorption sites and flexible transport channel (the interconnected 3D porous structure). A three-factor-three-level Box-Behnken design (BBD) was selected to optimize three greatly influential parameters: amount of adsorbent (A), desorption time (B) and volume of desorption solvent (C) by response surface methodology. The established method coupled to HPLC-UV detection showed wide linearity with the range of 0.2-450 µg•L-1, relatively low limits of detection (0.05-0.10 µg•L-1) with the relative standard deviation (RSD) (n = 7) lower t than 5.47%. Moreover, the proposed method was successfully applied to analyze BUs in tea samples and investigate the removal effect of different washing on BUs residues from tea leaf. These results indicated that the synthesized Fe2O3@C is a promising adsorbent material for magnetic solid phase extraction of BUs at trace concentrations from tea samples.


Assuntos
Inseticidas/análise , Nanopartículas de Magnetita/química , Estruturas Metalorgânicas/química , Chá/química , Ureia/análise , Adsorção , Carbono/química , Cromatografia Líquida de Alta Pressão/métodos , Cromatografia Líquida de Alta Pressão/normas , Compostos Férricos/química , Inseticidas/isolamento & purificação , Inseticidas/normas , Limite de Detecção , Porosidade , Padrões de Referência , Extração em Fase Sólida , Espectrofotometria Ultravioleta , Chá/metabolismo , Ureia/análogos & derivados , Ureia/isolamento & purificação , Ureia/normas
2.
Sci Total Environ ; 739: 139994, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32535469

RESUMO

There is an increasing pressure on temperate pastoral dairy production systems to reduce environmental impacts, coming from the inefficient use of N by cows in the form of excessive urinary N excretion and subsequent N leaching to the waterways and NO2 emissions to the atmosphere, these impacts have spurred research into various mitigation strategies, which have so far overlooked animal-based solutions. The objectives of this study were first, to investigate the relationship between MUN breeding values (MUNBV) and urinary urea N (UUN) concentrations and total excretion in grazing dairy cows; and secondly, to evaluate such a potential relationship in the context of different sward compositions and stage of lactation. Forty-eight multiparous, lactating Holstein-Friesian dairy cows genetically divergent for MUNBV were strip-grazed on either a ryegrass-white clover (24 cows) or ryegrass, white clover and plantain sward (24 cows), during both early and late lactation. Cows were fitted with Lincoln University PEETER sensors to evaluate urination behaviour by measuring frequency and volume of urination, as well as daily urine excretion. Urine and faeces were sampled for urea N content. Milk yield and composition were measured for individual cows in both periods. There was a positive relationship between MUNBV and MUN (R2 = 0.67, P ≤ 0.05), with MUN decreasing 1.61 ± 0.19 mg/dL per unit decrease in MUNBV across both sward types and stages of lactation. Urinary urea N concentration decreased 0.67 ± 0.27 g/L (R2 = 0.46, P ≤ 0.05) per unit decrease of MUNBV, with no effect on urine volume or frequency (number of urination events per day), which resulted in a 165.3 g/d difference in UUN excretion between the animal with the highest and the lowest MUNBV. At the same milk yield, percentage of protein in milk increased by 0.09 ± 0.03 (R2 = 0.61, P ≤ 0.05,) per unit decrease in MUNBV. Our results suggest that breeding and selecting for dairy cows with low MUNBV can reduce urinary urea N deposition onto pasture and consequently the negative environmental impact of pastoral dairy production systems in temperate grasslands. Moreover, reducing MUNBV of dairy cows can potentially increase farm profitability due to greater partitioning of N to milk in the form of protein.


Assuntos
Lactação , Leite/química , Animais , Cruzamento , Bovinos , Dieta , Feminino , Nitrogênio/análise , Ureia/análise
3.
Chemosphere ; 258: 127228, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32535438

RESUMO

Urea hydrolysis in partial nitritation process forming nitrite and ammonia is advantageous to subsequent treatment with ANAMMOX for total nitrogen removal. In this study, stable partial nitritation for urea wastewater with urea increasing from 250 to 2000 mg L-1 were achieved in an aerobic SBR. Urea removal efficiency and nitrite accumulation percentage both kept above 98%, with nitrite production rate about 0.985 kg N·m-3·d-1. Urea hydrolysis mechanism in this aerobic system was described as, (1) massive urea in the bulk was absorbed into cell, (2) urea was hydrolyzed by intracellular urease inside cell, (3) produced ammonia then slowly diffused into the bulk through membrane, which is later converted by ammonia-oxidizing bacteria (AOB) into nitrite. Due to this mechanism, the activity of AOB could not be inhibited by high FA (free ammonia) value under high urea concentration condition while nitrite-oxidizing bacteria (NOB) remained to be inhibited. An uncultured genus belonging to poorly characterized phylum Gemmatimonadetes was found enriched in this process and became dominant genus. This genus was speculated to have same energy pathway like ureaplasma, by absorbing excessive urea from environment and utilize urea hydrolysis to generate energy. So it was believed to be responsible for urea hydrolysis mechanism mentioned above. This SBR showed stable partial nitritation and high urea removal efficiency for treating urea wastewater, which was obviously feasible as the pretreatment process for subsequent ANAMMOX.


Assuntos
Amônia/análise , Reatores Biológicos/microbiologia , Nitritos/análise , Ureia/análise , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Aerobiose , Amônia/metabolismo , Bactérias/metabolismo , Hidrólise , Nitritos/metabolismo , Nitrogênio/análise , Nitrogênio/metabolismo , Oxirredução , Ureia/metabolismo , Águas Residuárias/química , Poluentes Químicos da Água/metabolismo
4.
Aust Vet J ; 98(8): 375-379, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32291747

RESUMO

OBJECTIVE: The aim of this study was to determine the relationship between milk urea nitrogen (MUN) and reproductive performance in dairy cows in western Thailand. DESIGN: All cows calving from November 2014 to April 2015 were included in the study, a total of 486 cows from 47 farms. Each cow had milk constituents and MUN tested monthly up to confirmed conception or until the 8th month after parturition. Each farm had a dietary assessment completed. Cox proportional hazard models with shared frailty were used to determine associations of conception rate. RESULTS: Cows became pregnant increasingly quickly over time, except during 100-150 days of lactation. A change in MUN from 12.5 to 13.5 mg/dL on the closet day to breeding was associated with a 5% decrease in conception. Milk protein was negatively associated with hazard of conception, whereas milk lactose and dietary protein:energy ratio had positive associations with conception rate. Breeding season was also significant; the highest conception rate was observed in cows inseminated during winter, whereas insemination during the humid rainy season resulted in the lowest conception rates. The farm random effect in the model was strongly significant. CONCLUSION: Detrimental effects of higher MUN on rate of conception were identified. The rate of conception was positively associated with protein:energy ratio in the study. Therefore, good nutritional management leading to positive energy balance should benefit conception rates.


Assuntos
Lactação , Leite/química , Animais , Bovinos , Indústria de Laticínios , Fazendas , Feminino , Nitrogênio/análise , Gravidez , Tailândia , Ureia/análise
5.
Food Chem ; 319: 126545, 2020 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-32169764

RESUMO

A sol-gel urea colorimetric method was developed for the determination of urea in feedstuffs. The sol-gel platform contained p-dimethylaminobenzaldehyde (p-DMAB) as the reagent entrapped within polymer network. The urea analysis relied on the formation of Schiff base under acidic conditions. The colorimetric product was imaged with a Smartphone. Under optimized conditions, the calibration curve for urea was linear over the concentration range of 2.5-100 and 100-1000 mg L-1 with a good coefficient of determination (r2 > 0.99). The limit of detection (LOD) and limit of quantification (LOQ) were 0.1 and 0.5 mg L-1, respectively. The intra-day and inter-day precisions were 0.83-3.01%RSD and 2.20-5.47%RSD, respectively. Accuracy of urea analysis ranged from -1.15 to 2.76%. The proposed method was stable for at least 90 days. The amount of urea in feedstuff sample was determined. The developed method is easy to use with small samples and reagent consumption in field conditions for monitoring the quality of feedstuff.


Assuntos
Ureia/análise , Benzaldeídos/química , Colorimetria/métodos , Limite de Detecção , Transição de Fase , Ureia/química
6.
J Breath Res ; 14(3): 036002, 2020 04 28.
Artigo em Inglês | MEDLINE | ID: mdl-32015218

RESUMO

Previous studies have shown that breath ammonia (breath-NH3) concentration is associated with blood urea nitrogen (BUN) levels. However, interindividual variations in breath-NH3 concentrations were observed. Thus, the present study aimed to assess the effect of oral cavity conditions on breath-NH3 concentration and to validate whether the measurement of breath-NH3 concentration is feasible in clinical settings. A total of 125 individuals, including patients with stage 3 to 5 chronic kidney disease (CKD3-5), those on dialysis, and healthy participants, were recruited. A nanostructured sensor was used to detect breath-NH3 concentrations. Pre- and post-gargling as well as pre- and post-hemodialysis (HD) breath-NH3, salivary pH, and salivary urea levels were measured. Breath-NH3, salivary urea, salivary pH, and BUN levels were positively correlated to each other. Breath-NH3 concentrations were associated with BUN levels (r = 0.43, p < 0.001) and were significantly higher in CKD3-5 (p < 0.005) and dialysis patients (p < 0.001) than in healthy participants. Higher correlation coefficients were noted between breath-NH3 concentrations and BUN levels during follow-up (r = 0.59-0.94, p < 0.05). When the cutoff value of breath-NH3 was set at 523.65 ppb, its sensitivity and specificity in predicting CKD (BUN level >24 mg dl-1) were 87.6% and 80.9%, respectively. Breath-NH3 concentrations decreased after HD (p < 0.001) and immediately after gargling (p < 0.01). Breath-NH3 concentration, which was affected by gargling, was correlated to BUN level. The measurement of breath-NH3 concentration using the nanostructured device may be used as a tool for CKD detection and personalized point-of-care for CKD and dialysis patients. The current study had a small sample size. Thus, further studies with a larger cohort must be conducted to validate the effect of oral factors on breath-NH3 concentration and to validate the benefit of breath-NH3 measurement.


Assuntos
Amônia/análise , Nitrogênio da Ureia Sanguínea , Testes Respiratórios/métodos , Diálise Renal , Insuficiência Renal Crônica/sangue , Adulto , Testes Respiratórios/instrumentação , Feminino , Humanos , Concentração de Íons de Hidrogênio , Masculino , Pessoa de Meia-Idade , Curva ROC , Insuficiência Renal Crônica/diagnóstico , Saliva/química , Ureia/análise
7.
J Dairy Sci ; 103(2): 1463-1471, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31837796

RESUMO

Previous research has demonstrated that feeding canola meal (CM) improves milk production and N utilization by lactating dairy cows when replacing solvent-extracted soybean meal (SBM). The objective of the present study was to evaluate whether CM would improve milk yield and components and N utilization, compared with SBM, at different ratios of alfalfa silage (AS) to corn silage (CS) fed to lactating dairy cows. Twenty-four multiparous Holstein cows averaging, at the beginning of the study (mean ± SD), 2.8 ± 0.9 parity, 684 ± 56 kg of BW, 102 ± 41 DIM, and 49 ± 4 kg milk/d, and 24 primiparous cows averaging (mean ± SD) 565 ± 46 kg of BW, 123 ± 30 DIM, and 40 ± 4 kg milk/d were blocked by parity and DIM. A cyclic changeover design with 4 replications of 2 blocks of treatments of 6 cows was used in an arrangement with 4 28-d periods. Dietary treatments were arranged in a 3 × 2 factorial design of 3 proportions of AS to CS as forage source (HAS = high AS, 50% AS to 10% CS; MAS = medium AS, 30% AS to 30% CS; LAS = low AS, 10% AS to 50% CS) and 2 protein supplements (CM vs. SBM). Diets were formulated to contain [dry matter (DM) basis]: 60% forage, 8 to 15% high-moisture corn, 2 to 5% soy hulls, 1.3% mineral-vitamin premix, 16% crude protein, and 31 to 33% NDF. Data from the last 2 weeks of each period were used to compute mean milk yield and composition, and efficiencies of feed conversion, for each cow in each period. Data for the other variables were collected during the last week of each period. All data were analyzed using the MIXED procedure of SAS (SAS Institute Inc., Cary, NC). Regardless of the forage source, replacing SBM with CM improved yields of milk, milk protein, and solids-not-fat. Moreover, milk urea nitrogen concentration and urinary excretion of total N (g/d) and urea N (% of total urinary N) decreased when CM replaced SBM. An interaction effect occurred between forage source and protein supplements for apparent total-tract digestibility, and, overall, this effect was due to small differences in ingredient and chemical compositions of the diets. In addition, these differences had a minor effect on cow performance. Yields of milk and milk components were greatest for cows fed 50% CS, intermediate for 30% CS, and lowest for 10% CS, indicating that, under the conditions of the present study, cows fed 50% CS in the diet (DM basis) had greater production compared with those fed 50% AS.


Assuntos
Brassica napus , Bovinos/fisiologia , Proteínas na Dieta/análise , Suplementos Nutricionais/análise , Leite/metabolismo , Silagem/análise , Animais , Dieta/veterinária , Feminino , Lactação , Medicago sativa , Leite/química , Proteínas do Leite/metabolismo , Nitrogênio/análise , Paridade , Gravidez , Soja , Ureia/análise , Zea mays
8.
Vet Clin North Am Exot Anim Pract ; 23(1): 103-114, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31759442

RESUMO

Reptile kidneys maintain a constant extracellular environment within the body. They excrete waste products, maintain normal concentrations of salt and water, regulate acid-base balance, and produce hormones and vitamins. The kidneys contain nephrons consisting of glomeruli designed to filter the plasma, Bowman capsules that collect the filtrate, and tubules that resorb most of the filtered water and nutrients while excreting waste metabolites. A Loop of Henle is absent. Therefore, reptile kidneys cannot produce a hypertonic urine. The urinary bladder (if present) and cloaca excrete and absorb additional fluids and electrolytes. A renal portal system is present in all reptiles.


Assuntos
Répteis/fisiologia , Animais , Rim/metabolismo , Répteis/anatomia & histologia , Ureia/análise , Ácido Úrico/análise , Bexiga Urinária/anatomia & histologia , Bexiga Urinária/fisiologia
9.
Vet Clin North Am Exot Anim Pract ; 23(1): 47-58, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31759451

RESUMO

Renal disease often remains undetected in living patients. Urinalysis might contribute to the diagnosis of some kinds of renal and metabolic diseases. Blood uric acid concentrations reflect the excretory functional capacity of the renal proximal tubules. In contrast, blood urea concentrations are significantly affected by the bird's hydration status and have been proposed as a useful variable to detect prerenal causes for renal impairment in birds. Measurement of exogenous creatinine excretion shows promising preliminary results to become a useful test for the assessment of renal excretion in birds.


Assuntos
Doenças das Aves/fisiopatologia , Creatinina/análise , Nefropatias/veterinária , Animais , Doenças das Aves/diagnóstico , Aves , Creatinina/metabolismo , Rim/metabolismo , Nefropatias/diagnóstico , Nefropatias/fisiopatologia , Nefrologia , Ureia/análise , Ácido Úrico/análise , Urinálise/veterinária
10.
Food Chem ; 302: 125371, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31437711

RESUMO

Dietary selenium deficiency is recognized as a global problem. Pork is the most widely consumed meat throughout the world and an important source of selenium for humans. In this study, a reliable approach was developed for analyzing selenium and its speciation in the muscles of pigs after different selenium treatments. The selenium source deposition efficiency was ranked as: selenomethionine > methylselenocysteine > selenite, and the muscle selenium content had a dose effect with selenomethionine supplementation. In total, four species of selenium were detected in the muscles of pigs and the distributions of these selenium species were greatly affected by the dietary selenium supplementation forms and levels. Selenomethionine (>70% of total selenium) and selenocystine (>11%) were the major selenium species, followed by methylselenocysteine and selenourea. Therefore, selenium-enriched pork produced from selenomethionine is a good source for improving human dietary selenium intake.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Espectrometria de Massas/métodos , Músculo Esquelético/química , Compostos de Selênio/farmacologia , Selênio/análise , Animais , Cistina/análogos & derivados , Cistina/análise , Suplementos Nutricionais , Análise de Alimentos/métodos , Masculino , Músculo Esquelético/efeitos dos fármacos , Compostos Organosselênicos/análise , Reprodutibilidade dos Testes , Ácido Selenioso/farmacologia , Compostos de Selênio/análise , Selenocisteína/análogos & derivados , Selenocisteína/farmacologia , Selenometionina/análise , Selenometionina/farmacologia , Suínos , Ureia/análogos & derivados , Ureia/análise
11.
Food Chem ; 303: 125375, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31476527

RESUMO

Urea is well-known to offer tremendous scope for sensing/diagnosing such as adulteration in dairy products or diseases in human body. This study was organized to describe and validate a new mediator-free, unsophisticated, and direct current voltage (IV)-based sensor for facile detection of urea using nanocomposites made of urease-immobilized graphene nanoplatelets and graphitized nanodiamonds. This nanocomposite displayed sensitive and direct signal in the form of current at 0 V without the need of any complex chemical reaction. This platform was highly sensitive (limit of detection of 5 µg/mL) far superior to the comparable systems introduced recently. The incorporation of graphitized nanodiamonds within the graphene nanoplatelets layers helped improve the sensitivity by a factor of three (up to 806.3 µA (mg mL-1)-1 cm-2) with 20 s response time. As such, the use of this nanocomposite was helpful in improving sensing performances with enhanced enzyme loading capacity.


Assuntos
Técnicas Eletroquímicas/métodos , Nanocompostos/química , Ureia/análise , Grafite/química , Nanodiamantes/química
12.
Food Chem ; 309: 125785, 2020 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-31732247

RESUMO

Skimmed milk powder can be blended with indigenous vegetable oils to formulate fat-filled milk powder (FMP) to satisfy the growing demand of low-income consumers for dairy proteins in the developing countries where food control systems may be fragmented. Unscrupulous manufacturers may adulterate FMP with melamine or urea to give the false impression that it contains sufficient protein. This study investigated, for the first time, the efficacy of near infrared spectroscopy to detect and quantify melamine and urea (0.01-16.00%) in FMP formulated with 4 different vegetable oils (i.e., coconut, palm, soya-bean and sunflower). Multilevel analyses were able to detect, confirm and differentiate the adulterations with an efficiency ranging from 89.8 to 100.0%. The partial least square regression models yielded satisfactory predictions (R2p ≥0.96, RSR ≤0.19) at adulteration levels ≥1.00%. This study provides appropriate guidelines for cost-efficient screening of FMP products for adulterants to protect public health.


Assuntos
Contaminação de Alimentos/análise , Leite/química , Espectroscopia de Luz Próxima ao Infravermelho , Triazinas/análise , Ureia/análise , Animais , Análise dos Mínimos Quadrados , Óleos Vegetais/química , Pós/química , Análise de Componente Principal
13.
Mikrochim Acta ; 187(1): 72, 2019 12 19.
Artigo em Inglês | MEDLINE | ID: mdl-31858252

RESUMO

A tapered single-mode coreless single-mode (SCS) structure with high sensitivity for sensing refractive index is described. In order to achieve high specificity of optical biosensors, here enzyme capsulation film was achieved by embedding urease in zeolitic imidazolate framework (ZIF-8/urease) through in situ growth approach on the coreless fibers. Determination of urea is achieved through online monitoring of its binding to the urease in zeolitic imidazolate framework. Refractive index change result in wavelength shifts of the optical fiber biosensor. The resonance wavelength exhibits a good linear relationship with urea concentration in the range of 1 to 10 mM with detection limit of 0.1 mM and sensitivity of 0.8 mM/RIU (refractive index unit) if operated with broadband light ranging from 1525 nm to 1590 nm. Final assessment of optical biosensor in real sample was performed where excellent performance in terms of sensitivity and selectivity was observed. Schematic representation of experimental setup and mechanism for urea detection. A tapered single-mode coreless single-mode (SCS) structure is placed between a broadband light source ranging (BBS) and optical spectrum analyzer (OSA). ZIF-8/urease composites are applied as a recognition layer for urea detection.


Assuntos
Técnicas Biossensoriais , Enzimas Imobilizadas/química , Estruturas Metalorgânicas/química , Ureia/análise , Urease/química , Zeolitas/química , Enzimas Imobilizadas/metabolismo , Estruturas Metalorgânicas/metabolismo , Fibras Ópticas , Tamanho da Partícula , Propriedades de Superfície , Ureia/metabolismo , Urease/metabolismo , Zeolitas/metabolismo
14.
BMC Plant Biol ; 19(1): 466, 2019 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-31684880

RESUMO

BACKGROUND: Sesame (Sesame indicum L.) is well-known as a versatile industrial crop having various usages and contains 50-55% oil, 20% protein, 14-20% carbohydrate and 2-3% fiber. Several environmental factors are known to adversely affect yield and productivity of sesame. Our overall aim was to improve the growth, yield and quality of sesame cv. TS-3 using plant growth promoting rhizobacteria (PGPR) and saving the nitrogen and phosphate fertilizers (NP) by 50%. Field experiment (randomized complete block design) was conducted during the months of July to October of two consecutive years 2012-2013. Azospirillum (AL) and Azotobacter (AV) were applied as seed inoculation alone as well as along with half of the recommended dose of nitrogen (N) and phosphate (P) fertilizers (urea and diammonium phosphate) at the rate of 25 kg/ha and 30 kg/ha respectively. RESULTS: Here we report that A. lipoferum along with half dose of NP fertilizers (ALCF) were highly effective in increasing the agronomic and yield traits of sesame as compared to the control. A. vinelandii plus NP fertilizers (AVCF) exhibited higher seed oil content. Minimum acid value, optimum specific gravity and modified fatty acid composition were observed in ALCF treatment. Increase in oleic acid by ALCF is directly linked with improved oil quality for health benefits as oleic acid is the fatty acid which creates a balance between saturation and unsaturation of oil and for the hypotensive (blood pressure reducing) effects. CONCLUSION: It is inferred that ALCF treatment improved plant growth, seed yield and oil quality of sesame pertaining to good quality edible oil production.


Assuntos
Azospirillum lipoferum/química , Azotobacter vinelandii/química , Valor Nutritivo , Óleo de Gergelim/análise , Sesamum/química , Sesamum/crescimento & desenvolvimento , Fertilizantes/análise , Fosfatos/análise , Distribuição Aleatória , Ureia/análise
15.
Sensors (Basel) ; 19(20)2019 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-31635177

RESUMO

The goal of this study was to reduce the drift effect of RuO2 urea biosensors. A new calibration circuit (NCC) based on the voltage regulation technique with the advantage of having a simple structure was presented. To keep its simplicity, the proposed NCC was composed of a non-inverting amplifier and a voltage calibrating circuit. A ruthenium oxide (RuO2) urea biosensor was fabricated to test the calibrating characteristics of the drift rate of the proposed NCC. The experiment performed in this study was divided into two main stages. For the first stage, a sound RuO2 urea biosensor testing environment was set-up. The RuO2 urea sensing film was immersed in the urea solution for 12 h and the response voltage was measured using the voltage-time (V-T) measurement system and the proposed NCC. The results of the first stage showed that the RuO2 urea biosensor has an average sensitivity of 1.860 mV/(mg/dL) and has a linearity of 0.999 which means that the RuO2 urea biosensor had been well fabricated. The second stage of the experiment verified the proposed NCC's functions, and the results indicated that the proposed NCC reduced the drift rate of RuO2 urea biosensor to 0.02 mV/hr (98.77% reduction).


Assuntos
Técnicas Biossensoriais/métodos , Ureia/análise , Técnicas Biossensoriais/normas , Calibragem , Técnicas Eletroquímicas , Limite de Detecção , Polietilenotereftalatos/química , Compostos de Rutênio/química , Ureia/normas
16.
Sensors (Basel) ; 19(20)2019 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-31635189

RESUMO

A portable urea sensor for use in fast flow conditions was fabricated using porous polytetrafluoroethylene (PTFE) membranes coated with amine-functionalized parylene, parylene-A, by vapor deposition. The urea-hydrolyzing enzyme urease was immobilized on the parylene-A-coated PTFE membranes using glutaraldehyde. The urease-immobilized membranes were assembled in a polydimethylsiloxane (PDMS) fluidic chamber, and a screen-printed carbon three-electrode system was used for electrochemical measurements. The success of urease immobilization was confirmed using scanning electron microscopy, and fourier-transform infrared spectroscopy. The optimum concentration of urease for immobilization on the parylene-A-coated PTFE membranes was determined to be 48 mg/mL, and the optimum number of membranes in the PDMS chamber was found to be eight. Using these optimized conditions, we fabricated the urea biosensor and monitored urea samples under various flow rates ranging from 0.5 to 10 mL/min in the flow condition using chronoamperometry. To test the applicability of the sensor for physiological samples, we used it for monitoring urea concentration in the waste peritoneal dialysate of a patient with chronic renal failure, at a flow rate of 0.5 mL/min. This developed urea biosensor is considered applicable for (portable) applications, such as artificial kidney systems and portable dialysis systems.


Assuntos
Técnicas Biossensoriais/métodos , Soluções para Diálise/análise , Membranas Artificiais , Polímeros/química , Politetrafluoretileno/química , Ureia/análise , Xilenos/química , Técnicas Biossensoriais/instrumentação , Técnicas Eletroquímicas , Enzimas Imobilizadas/química , Humanos , Diálise Peritoneal , Insuficiência Renal Crônica/patologia , Urease/química , Urease/metabolismo
17.
J Dairy Sci ; 102(11): 9814-9826, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31447165

RESUMO

Dry matter intake, lactation performance, and chewing behavior of multiparous Holstein cows (n = 15) fed diets containing a novel bm3 corn silage hybrid with floury kernel genetics were compared with cows fed diets containing commercially available conventional and bm3 hybrids using a replicated 3 × 3 Latin square design with 28-d periods. Cows were housed in tiestalls, milked 3 times/d, and fed a total mixed ration containing 49.0% (dry matter basis) of (1) a conventional corn silage hybrid (CONV); (2) a brown midrib bm3 hybrid (BMR); or (3) a bm3 hybrid with floury kernel genetics (BMRFL). All diets contained 6.3% hay crop silage and 44.7% concentrate. Dietary nutrient composition averaged 32.7% neutral detergent fiber (NDF) and 26.3 starch (% of dry matter). Data were analyzed by ANOVA using the MIXED procedure in SAS (SAS Institute Inc., Cary, NC). The dry matter intake was greater for cows fed BMR (28.0 kg/d) compared with CONV (26.8 kg/d), whereas dry matter intake for cows fed BMRFL was intermediate (27.6 kg/d). Energy-corrected milk (ECM) yield was greater for cows fed BMR (50.3 kg/d) and BMRFL (51.8 kg/d) compared with CONV (47.2 kg/d). Milk fat yield was higher for cows fed BMRFL (1.87 kg/d) compared with CONV (1.74 kg/d) and BMR (1.80 kg/d). Milk protein yield was greater for cows fed BMR (1.49 kg/d) and BMRFL (1.54 kg/d) compared with CONV (1.36 kg/d). Milk urea-N was reduced for cows fed BMR (11.61 mg/dL) and BMRFL (11.16 mg/dL) compared with CONV (13.60 mg/dL). Feed efficiency (ECM/dry matter intake) was higher for cows fed BMRFL (1.87) compared with CONV (1.76) and BMR (1.79). Milk N efficiency was greatest for cows fed BMRFL (40.4%) followed by BMR (38.1%) and finally CONV (35.3%). Cows fed CONV chewed 5 min more per kilograms of NDF consumed than cows fed either of the BMR hybrids. No differences were observed among diets in apparent total-tract digestibility of NDF (58.1%) or starch (99.3%). Overall lactational performance was enhanced for cows fed diets containing both BMR and BMRFL hybrids versus CONV. In addition, feeding the BMRFL corn silage improved efficiency of component-corrected milk production and milk N efficiency compared with the CONV and BMR silages.


Assuntos
Bovinos/fisiologia , Fibras na Dieta/metabolismo , Leite/metabolismo , Silagem/análise , Amido/metabolismo , Zea mays , Animais , Indústria de Laticínios , Dieta/veterinária , Ingestão de Alimentos , Feminino , Farinha/análise , Lactação , Mastigação , Leite/química , Proteínas do Leite/metabolismo , Ureia/análise
18.
Arq Gastroenterol ; 56(2): 197-201, 2019 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-31460586

RESUMO

BACKGROUND: 13C-urea breath test (UBT) is the gold-standard, noninvasive method for H. pylori diagnosis. However, there is no uniform standardization of the test. This situation can be unpractical for laboratories running with two or more devices. OBJECTIVE: To perform a prospective comparison validation study of UBT employing one validated protocol for two different devices: BreathID Hp Lab System® (Exalenz Bioscience Ltd, Israel), here called device A and IRIS-Doc2® (Wagner Analysen-Technik, Germany, now Mayoly Spindler Group, France), here called device B, in the diagnosis of H. pylori infection. METHODS: A total of 518 consecutive patients (365 females, 153 males, mean age 53 years) referred for UBT were included. All patients received device A protocol as follow: after at least one hour fasting, patients filled two bags prior to the test, then ingested an aqueous solution containing 75 mg of 13C-urea with a 4.0 g citric acid powder and filled another two bags 15 min after ingesting the test solution. One pair of breath sample bags (before and after ingestion) was analyzed by the two different devices. A delta over baseline (DOB) ≥5‰ indicated H. pylori infection. Statistics: Wilcoxon test, kappa coefficient with 95% CI, Wilson's method. RESULTS: Considering the device A protocol as the gold standard, its comparison with device B showed a sensitivity of 99.3% (95% CI: 96.3-99.9) and a specificity of 98.9% (95% CI: 97.3-99.6). Kappa coefficient was 0.976 (95% IC: 0.956-0.997). CONCLUSION: Correlation between the two devices was excellent and supports a uniform standardization of UBT.


Assuntos
Testes Respiratórios/instrumentação , Infecções por Helicobacter/diagnóstico , Ureia/análise , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Testes Respiratórios/métodos , Criança , Protocolos Clínicos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Sensibilidade e Especificidade , Adulto Jovem
19.
Sensors (Basel) ; 19(16)2019 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-31408931

RESUMO

Conceptual and commercial examples of implantable sensors have been limited to a relatively small number of target analytes, with a strong focus on glucose monitoring. Recently, surface-enhanced Raman spectroscopy (SERS) pH sensors were demonstrated to track acid-producing enzymatic reactions targeting specific analytes. We show here that SERS pH tracking in the basic regime is also possible, and can be used to monitor urea concentration. To accomplish this, we developed a hydrogel consisting of polyelectrolyte multilayer microcapsules containing a SERS-sensitive pH reporter (4-mercapopyridine capped silver nanoparticles modified with bovine serum albumin). This pH sensing material exhibited a sensitive Raman scattering response to a wide range of pH from 6.5-9.7. By incorporating urease into the hydrogel matrix, the new sensor was capable of distinguishing urea concentrations of 0, 0.1, 1, and 10 mM. We also found that bovine serum albumin (BSA) prevented severe aggregation of the nanoparticle-based pH sensor, which improved sensing range and sensitivity. Furthermore, BSA safeguarded the pH sensor during the encapsulation procedure. Together, the combination of materials represents a novel approach to enabling optical sensing of reactions that generate pH changes in the basic range.


Assuntos
Hidrogéis/química , Nanopartículas Metálicas/química , Prata/química , Análise Espectral Raman/métodos , Ureia/análise , Animais , Cápsulas/química , Bovinos , Hidrogéis/síntese química , Concentração de Íons de Hidrogênio , Polieletrólitos/química , Coroa de Proteína/química , Soroalbumina Bovina/química
20.
Artigo em Inglês | MEDLINE | ID: mdl-31393235

RESUMO

Urea is a non-protein nitrogen compound, authorised in the EU as a nutritional source of nitrogen in animal feed intended for ruminants with a functional rumen. The Rapid Alert System for Food and Feed (RASFF) is the EU online platform through which food and feed safety risks are reported. During 2017, several rapid alerts were raised in the EU by individual member states regarding the presence of unlabelled urea in feed-grade yeast. The presence of urea in animal feed is analysed with a spectro-colorimetric method, which is the EU official control method. Other urea analytical methods include enzymatic and LC-MS methods, which are also investigated in this study. The main objectives of this study were to analyse yeast feed-grade and food-grade products with independent laboratories using the EU official control method, as well as enzymatic and LC-MS methods. Comparison of results from the spectro-colorimetric, enzymatic and LC-MS methods for reliability, consistency and accuracy determined the most reliable method for the quantification of urea in animal feed. Yeast food and feed samples were tested using four independent laboratories. Results demonstrated a lack of consistency both within the same laboratory and between separate laboratories for urea quantification using the EU official control method. Urea quantification results for the AOAC 941.04 enzymatic method were found to be much higher than anticipated. The LC-MS method yielded the most consistent and reliable results. In conclusion, urea quantification by LC-MS analysis has the potential to be a viable method for urea analysis of yeast samples.


Assuntos
Ração Animal/análise , Análise de Alimentos , Saccharomyces cerevisiae/química , Saccharomyces cerevisiae/isolamento & purificação , Ureia/análise , Animais , Cromatografia Líquida , Colorimetria , Espectrometria de Massas
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