Sequence-specific electrochemical detection of Alicyclobacillus acidoterrestris DNA using electroconductive polymer-modified fluorine tin oxide electrodes

This study outlines the quantification of low levels of Alicyclobacillus acidoterrestris in pure cultures, since this bacterium is not inactivated by pasteurization and may remain in industrialized foods and beverages. Electroconductive polymer-modified fluorine tin oxide (FTO) electrodes and multiple nanoparticle labels were used for biosensing. The detection of A. acidoterrestris in pure cultures was performed by reverse transcription polymerase chain reaction (RT-PCR) and the sensitivity was further increased by asymmetric nested RT-PCR using electrochemical detection for quantification of the amplicon. The quantification of nested RT-PCR products by Ag/Au-based electrochemical detection was able to detect 2 colony forming units per mL (CFU mL(-1)) of spores in pure culture and low detection and quantification limits (7.07 and 23.6 nM, respectively) were obtained for the target A. acidoterrestris on the electrochemical detection bioassay.

Near infrared spectroscopy for soil bulk density assessment

P>Soil bulk density values are needed to convert organic carbon content to mass of organic carbon per unit area. However, field sampling and measurement of soil bulk density are labour-intensive, costly and tedious. Near-infrared reflectance spectroscopy (NIRS) is a physically non-destructive, rapid, reproducible and low-cost method that characterizes materials according to their reflectance in the near-infrared spectral region. The aim of this paper was to investigate the ability of NIRS to predict soil bulk density and to compare its performance with published pedotransfer functions. The study was carried out on a dataset of 1184 soil samples originating from a reforestation area in the Brazilian Amazon basin, and conventional soil bulk density values were obtained with metallic ""core cylinders"". The results indicate that the modified partial least squares regression used on spectral data is an alternative method for soil bulk density predictions to the published pedotransfer functions tested in this study. The NIRS method presented the closest-to-zero accuracy error (-0.002 g cm-3) and the lowest prediction error (0.13 g cm-3) and the coefficient of variation of the validation sets ranged from 8.1 to 8.9% of the mean reference values. Nevertheless, further research is required to assess the limits and specificities of the NIRS method, but it may have advantages for soil bulk density predictions, especially in environments such as the Amazon forest.

Neutron Activation Analysis: A Primary (Ratio) Method to Determine SI-Traceable Values of Element Content in Complex Samples

The metrological principles of neutron activation analysis are discussed. It has been demonstrated that this method can provide elemental amount of substance with values fully traceable to the SI. The method has been used by several laboratories worldwide in a number of CCQM key comparisons - interlaboratory comparison tests at the highest metrological level - supplying results equivalent to values from other methods for elemental or isotopic analysis in complex samples without the need to perform chemical destruction and dissolution of these samples. The CCOM accepted therefore in April 2007 the claim that neutron activation analysis should have the similar status as the methods originally listed by the CCOM as `primary methods of measurement`. Analytical characteristics and scope of application are given.

Optimization and validation of a LIBS method for the determination of macro and micronutrients in sugar cane leaves

Laser induced breakdown spectrometry (LIBS) was applied for the determination of macro (P, K, Ca, Mg) and micronutrients (B, Cu, Fe, Mn and Zn) in sugar cane leaves, which is one of the most economically important crops in Brazil. Operational conditions were previously optimized by a neuro-genetic approach, by using a laser Nd:YAG at 1064 nm with 110 mJ per pulse focused on a pellet surface prepared with ground plant samples. Emission intensities were measured after 2.0 mu s delay time, with 4.5 mu s integration time gate and 25 accumulated laser pulses. Measurements of LIBS spectra were based on triplicate and each replicate consisted of an average of ten spectra collected in different sites (craters) of the pellet. Quantitative determinations were carried out by using univariate calibration and chemometric methods, such as PLSR and iPLS. The calibration models were obtained by using 26 laboratory samples and the validation was carried out by using 15 test samples. For comparative purpose, these samples were also microwave-assisted digested and further analyzed by ICP OES. In general, most results obtained by LIBS did not differ significantly from ICP OES data by applying a t-test at 95% confidence level. Both LIBS multivariate and univariate calibration methods produced similar results, except for Fe where better results were achieved by the multivariate approach. Repeatability precision varied from 0.7 to 15% and 1.3 to 20% from measurements obtained by multivariate and univariate calibration, respectively. It is demonstrated that LIBS is a powerful tool for analysis of pellets of plant materials for determination of macro and micronutrients by choosing calibration and validation samples with similar matrix composition.

Multifractal regime transition in a modified minority game model

The search for more realistic modeling of financial time series reveals several stylized facts of real markets. In this work we focus on the multifractal properties found in price and index signals. Although the usual minority game (MG) models do not exhibit multifractality, we study here one of its variants that does. We show that the nonsynchronous MG models in the nonergodic phase is multifractal and in this sense, together with other stylized facts, constitute a better modeling tool. Using the structure function (SF) approach we detected the stationary and the scaling range of the time series generated by the MG model and, from the linear (non-linear) behavior of the SF we identified the fractal (multifractal) regimes. Finally, using the wavelet transform modulus maxima (WTMM) technique we obtained its multifractal spectrum width for different dynamical regimes. (C) 2009 Elsevier Ltd. All rights reserved.

Efficient method for obtaining Lep(ob)/Lep(ob)-derived animal models using adipose tissue transplantations

Background: Leptin-deficient mice (Lep(ob)/Lep(ob), also known as ob/ob) are of great importance for studies of obesity, diabetes and other correlated pathologies. Thus, generation of animals carrying the Lep(ob) gene mutation as well as additional genomic modifications has been used to associate genes with metabolic diseases. However, the infertility of Lep(ob)/Lep(ob) mice impairs this kind of breeding experiment. Objective: To propose a new method for production of Lep(ob)/Lep(ob) animals and Lep(ob)/Lep(ob)-derived animal models by restoring the fertility of Lep(ob)/Lep(ob) mice in a stable way through white adipose tissue transplantations. Methods: For this purpose, 1 g of peri-gonadal adipose tissue from lean donors was used in subcutaneous transplantations of Lep(ob)/Lep(ob) animals and a crossing strategy was established to generate Lep(ob)/Lep(ob)-derived mice. Results: The presented method reduced by four times the number of animals used to generate double transgenic models (from about 20 to 5 animals per double mutant produced) and minimized the number of genotyping steps (from 3 to 1 genotyping step, reducing the number of Lep gene genotyping assays from 83 to 6). Conclusion: The application of the adipose transplantation technique drastically improves both the production of Lep(ob)/Lep(ob) animals and the generation of Lep(ob)/Lep(ob)-derived animal models. International Journal of Obesity (2009) 33, 938-944; doi: 10.1038/ijo.2009.95; published online 16 June 2009

Neuromuscular activity during bench press exercise performed with and without the preexhaustion method

Brennecke, A, Guimaraees, TM, Leone, R, Cadarci, M, Mochizuki, L, Simao, R, Amadio, AC, and Serrao, J. Neuromuscular activity during bench press exercise performed with and without the preexhaustion method. J Strength Cond Res 23(7): 1933-1940, 2009-The purpose of the present study was to investigate the effects of exercise order on the tonic and phasic characteristics of upper-body muscle activity during bench press exercise in trained subjects. The preexhaustion method involves working a muscle or a muscle group combining a single-joint exercise immediately followed by a multi-joint exercise (e. g., flying exercise followed by bench press exercise). Twelve subjects performed 1 set of bench press exercises with and without the preexhaustion method following 2 protocols (P1-flying before bench press; P2-bench press). Both exercises were performed at a load of 10 repetition maximum (10RM). Electromyography (EMG) sampled at 1 kHz was recorded from the pectoralis major (PM), anterior deltoid (DA), and triceps brachii (TB). Kinematic data (60 Hz) were synchronized to define upward and downward phases of exercise. No significant (p > 0.05) changes were seen in tonic control of PM and DA muscles between P1 and P2. However, TB tonic aspect of neurophysiologic behavior of motor units was significantly higher (p < 0.05) during P1. Moreover, phasic control of PM, DA, and TB muscles were not affected (p > 0.05). The kinematic pattern of movement changed as a result of muscular weakness in P1. Angular velocity of the right shoulder performed during the upward phase of the bench press exercise was significantly slower (p < 0.05) during P1. Our results suggest that the strategies set by the central nervous system to provide the performance required by the exercise are held constant throughout the exercise, but the tonic aspects of the central drive are increased so as to adapt to the progressive occurrence of the neuromuscular fatigue. Changes in tonic control as a result of the muscular weakness and fatigue can cause changes in movement techniques. These changes may be related to limited ability to control mechanical loads and mechanical energy transmission to joints and passive structures.

Correlation of Modified Natural Rubber Properties by Artificial Neural Networks

Natural rubber (NR) is a raw material largely used by the modern industry; however, it is common that chemical modifications must be made to NR in order to improve properties such as hydrophobicity or mechanical resistance. This work deals with the correlation of properties of NR modified with dimethylaminoethylmethacrylate or methylmethacrylate as grafting agents. Dynamic-mechanical behavior and stress/strain relations are very important properties because they furnish essential characteristics of the material such as glass transition temperature and rupture point. These properties are concerned with different physical principles; for this reason, normally they are not related to each other. This work showed that they can be correlated by artificial neural networks (ANN). So, from one type of assay, the properties that as a rule only could be obtained from the other can be extracted by ANN correlation. POLYM. ENG. SCI., 49:499-505, 2009. (c) 2009 Society of Plastics Engineers

An investigation of phosphate adsorption from aqueous solution onto hydrous niobium oxide prepared by co-precipitation method

The synthetic hydrous niobium oxide has been used for phosphate removal from the aqueous solutions. The kinetic data correspond very well to the pseudo second-order equation The phosphate removal tended. to increase with a decrease of pH. The equilibrium data describe very well the Langmuir isotherm. The peak appearing at 1050 cm(-1) in IR spectra after adsorption was attributed to the bending vibration of adsorbed phosphate. The adsorption capacities are high, and increased with increasing temperature. The evaluated Delta G degrees and Delta H degrees indicate the spontaneous and endothermic nature of the reactions. The adsorptions occur with increase in entropy (Delta S positive) value suggest increase in randomness at the solid-liquid interface during the adsorption. A phosphate desorbability of approximately 60% was observed with water at pH 12, which indicated a relatively strong bonding between the adsorbed phosphate and the sorptive sites on the surface of the adsorbent. (C) 2008 Elsevier B.V. All rights reserved.

EFFECT OF CULTIVATION CONDITIONS ON GLUCOSE-6-PHOSPHATE DEHYDROGENASE PRODUCTION BY GENETICALLY MODIFIED Saccharomyces cerevisiae

The objective of this research was to improve Glucose-6-phosphate dehydrogenase (G6PD) production by Saccharomyces cerevisiae W303-181, which carry the plasmid YEpPGK-G6PD, by varying the following cultivation conditions: pH value (4.8, 5.7 and 6.6); inoculum concentration (0.1, 0.6 and 1.1 g/L) and initial glucose concentration (20.0, 30.0 and 40.0 g/L). The effect of those variables on G6PD production capability was studied by the application of response surface statistical analysis. The results showed that the highest G6PD production (1594.2 U/L), specific activity (1189.7 U/g(cell)) and productivity (45.6 U/L.h) occurred at pH 4.8, inoculum concentration of 0.1 g/L and initial glucose concentration of 20.0 g/L, under agitation of 150 rpm at 30 degrees C after 36 h. In this work, the strain expressed about 21 fold more activity than the wild S. cerevisiae strain, being an attractive and promising new source of this enzyme.

Pseudomonas fluorescens lipase immobilization on polysiloxane-polyvinyl alcohol composite chemically modified with epichlorohydrin

The technique based on sol-gel approach was used to generate silica matrices derivatives by hydrolysis of silane compounds. The present work evaluates a hybrid matrix obtained with tetraethoxysilane (TEOS) and polyvinyl alcohol (PVA) on the immobilization yield of lipase from Pseudomonas fluorescens. The resulting polysiloxane-polyvinyl alcohol (POS-PVA) matrix combines the property of PVA as a suitable polymer to retain proteins with an excellent optical, thermal and chemical stability of the host silicon oxide matrix. Aiming to render adequate functional groups to the covalent binding with the enzyme the POS-PVA matrix was chemically modified using epichlorohydrin. The results were compared with immobilized derivative on POS-PVA activated with glutaraldehyde. Immobilization yield based on the recovered lipase activity depended on the activating agent and the highest efficiency (32%) was attained when lipase was immobilized on POS-PVA activated with epichlorohydrin, which, probably, provided more linkage points for the covalent bind of the enzyme on the support. This was confirmed by determining the morphological properties using different techniques as X-ray diffraction and scanning electron microscopy (SEM). Comparative studies were carried out to attain optimal activities for free lipase and immobilized systems. For this purpose, a central composite experimental design with different combinations of pH and temperature was performed. Enzymatic hydrolysis with the immobilized enzyme in the framework of the Michaelis-Menten mechanism was also reported. Under optimum conditions, the immobilized derivative on POS-PVA activated with epichlorohydrin showed to have more affinity for the substrate in the hydrolysis of olive oil, with a Michaelis-Menten constant value (K-m) of 293 mM, compared to the value of 401 mM obtained for the immobilized lipase on support activated with glutaraldehyde. Data generated by DSC showed that both immobilized derivatives have similar thermal stabilities. (C) 2007 Elsevier B.V. All rights reserved.

Covalent attachment of Candida rugosa lipase on chemically modified hybrid matrix of polysiloxane-polyvinyl alcohol with different activating compounds

Candida rugosa lipase was immobilized by covalent binding on hybrid matrix of polysiloxane-polyvinyl alcohol chemically modified with different activating agents as glutaraldehyde, sodium metaperiodate and carbonyldiimidazole. The experimental results suggested that functional activating agents render different interactions between enzyme and support, producing consequently alterations in the optimal reaction conditions. Properties of the immobilized systems were assessed and their performance on hydrolytic and synthetic reactions were evaluated and compared with the free enzyme. In hydrolytic reactions using p-nitrophenyl palmitate as substrate all immobilized systems showed higher thermal stability and optima pH and temperature values in relation to the free lipase. Among the activating compounds, carbonyldiimidazole resulted in a total recovery of activity on the support and the highest thermal stability. For the butyl butyrate synthesis, the best performance (molar conversion of 95% and volumetric productivity of 2.33 g L-1 h(-1)) was attained with the lipase immobilized on POS-PVA activated with sodium metaperiodate. The properties of the support and immobilized derivatives were also evaluated by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopies and chemical composition (FTIR). (c) 2007 Elsevier B.V. All rights reserved.

Thermodynamic and kinetic investigations of phosphate adsorption onto hydrous niobium oxide prepared by homogeneous solution method

The adsorption kinetics of phosphate onto Nb(2)O(5)center dot nH(2)O was investigated at initial phosphate concentrations 10 and 50 mg L(-1). The kinetic process was described by a pseudo second-order rate model very well. The adsorption thermodynamics was carried out at 298, 308, 318, 328 and 338 K. The positive values of both Delta H and Delta S suggest an endothermic reaction and increase in randomness at the solid-liquid interface during the adsorption. Delta G values obtained were negative indicating a spontaneous adsorption process. The Langmuir model described the data better than the Freundlich isotherm model. The peak appearing at 1050 cm(-1) in IR spectra after adsorption was attributed to the bending vibration of adsorbed phosphate. The effective desorption could be achieved using water at pH 12. (C) 2010 Elsevier B.V. All rights reserved.

Adsorption kinetic, thermodynamic and desorption studies of phosphate onto hydrous niobium oxide prepared by reverse microemulsion method

A type of Nb(2)O(5)center dot 3H(2)O was synthesized and its phosphate removal potential was investigated in this study. The kinetic study, adsorption isotherm, pH effect, thermodynamic study and desorption were examined in batch experiments. The kinetic process was described by a pseudo-second-order rate model very well. The phosphate adsorption tended to increase with a decrease of pH. The adsorption data fitted well to the Langmuir model with which the maximum P adsorption capacity was estimated to be 18.36 mg-Pg(-1). The peak appearing at 1050 cm(-1) in IR spectra after adsorption was attributed to the bending vibration of adsorbed phosphate. The positive values of both Delta H degrees and Delta S degrees suggest an endothermic reaction and increase in randomness at the solid-liquid interface during the adsorption. Delta G degrees values obtained were negative indicating a spontaneous adsorption process. A phosphate desorbability of approximately 68% was observed with water at pH 12, which indicated a relatively strong bonding between the adsorbed phosphate and the sorptive sites on the surface of the adsorbent. The immobilization of phosphate probably occurs by the mechanisms of ion exchange and physicochemical attraction. Due to its high adsorption capacity, this type of hydrous niobium oxide has the potential for application to control phosphorus pollution.

Sensorless synchronization method for thin-film direct optical broadband monitoring system

Optical monitoring systems are necessary to manufacture multilayer thin-film optical filters with low tolerance on spectrum specification. Furthermore, to have better accuracy on the measurement of film thickness, direct monitoring is a must. Direct monitoring implies acquiring spectrum data from the optical component undergoing the film deposition itself, in real time. In making film depositions on surfaces of optical components, the high vacuum evaporator chamber is the most popular equipment. Inside the evaporator, at the top of the chamber, there is a metallic support with several holes where the optical components are assembled. This metallic support has rotary motion to promote film homogenization. To acquire a measurement of the spectrum of the film in deposition, it is necessary to pass a light beam through a glass witness undergoing the film deposition process, and collect a sample of the light beam using a spectrometer. As both the light beam and the light collector are stationary, a synchronization system is required to identify the moment at which the optical component passes through the light beam.